<PAGE>
   AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON DECEMBER 21, 2000
 
                                                     REGISTRATION NO. 333-
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                           --------------------------
 
                                    FORM S-1
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                           --------------------------
 
                          ACADIA PHARMACEUTICALS INC.
             (Exact Name of Registrant as Specified in its Charter)
 

<TABLE>
<S>                              <C>                              <C>
           DELAWARE                           2834                          06-1376651
(State or Other Jurisdiction of   (Primary Standard Industrial           (I.R.S. Employer
Incorporation or Organization)     Classification Code Number)        Identification Number)
</TABLE>

 
                         3911 SORRENTO VALLEY BOULEVARD
                              SAN DIEGO, CA 92121
                                 (858) 558-2871
         (Address, Including Zip Code, and Telephone Number, Including
            Area Code, of Registrant's Principal Executive Offices)
                           --------------------------
 
                              ULI HACKSELL, PH.D.
                            CHIEF EXECUTIVE OFFICER
                          ACADIA PHARMACEUTICALS INC.
                         3911 SORRENTO VALLEY BOULEVARD
                              SAN DIEGO, CA 92121
                                 (858) 558-2871
           (Name, Address, Including Zip Code, and Telephone Number,
                   Including Area Code, of Agent for Service)
                           --------------------------
 
                                   COPIES TO:
 

<TABLE>
<S>                                              <C>
                D. BRADLEY PECK                                  FAYE H. RUSSELL
                GLENN F. BAITY                                 JEFFREY C. THACKER
               CHESTON J. LARSON                                SHERRY E. SCHNELL
              Cooley Godward LLP                         Brobeck, Phleger & Harrison LLP
       4365 Executive Drive, Suite 1100                       12390 El Camino Real
              San Diego, CA 92121                              San Diego, CA 92130
                (858) 550-6000                                   (858) 720-2500
</TABLE>

 
                           --------------------------
 
        APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:
   As soon as practicable after the Registration Statement becomes effective.
                           --------------------------
 
    If any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, check the following box. / /
 
    If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. / /
 
    If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. / /
 
    If this Form is a post-effective amendment filed pursuant to Rule 462(d)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. / /
 
    If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. / /
                           --------------------------
 

                        CALCULATION OF REGISTRATION FEE
 

<TABLE>
<CAPTION>
         TITLE OF EACH CLASS OF                  PROPOSED MAXIMUM AGGREGATE                        AMOUNT OF
      SECURITIES TO BE REGISTERED                    OFFERING PRICE(1)                          REGISTRATION FEE
<S>                                       <C>                                       <C>
Common Stock, $0.0001 par value.........                $75,000,000                                 $19,800
</TABLE>

 
(1) Estimated solely for the purpose of computing the registration fee pursuant
    to Rule 457(o) under the Securities Act of 1933. Includes $11,250,000 of
    shares that the underwriters have the option to purchase to cover
    overallotments, if any.
                           --------------------------
 
    THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT THAT SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF
THE SECURITIES ACT OF 1933, AS AMENDED, OR UNTIL THE REGISTRATION STATEMENT
SHALL BECOME EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID
SECTION 8(a), MAY DETERMINE.
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

<PAGE>
                                EXPLANATORY NOTE
 
    This registration statement contains two forms of prospectus front cover
page: (a) one to be used in connection with an offering in the United States and
Canada and (b) one to be used in connection with a concurrent offering outside
of the United States and Canada. The U.S./Canadian prospectus and the
international prospectus are otherwise identical in all respects. The
international version of the front cover page is included immediately before

Part II of this registration statement.

<PAGE>
                 SUBJECT TO COMPLETION, DATED            , 2001
 
THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY
NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER
TO SELL SECURITIES, AND WE ARE NOT SOLICITING OFFERS TO BUY THESE SECURITIES, IN
ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

<PAGE>
                                 [ACADIA LOGO]
 
                                        SHARES
                                  COMMON STOCK
 
    ACADIA Pharmaceuticals Inc. is offering             shares of its common
stock. This is our initial public offering and no public market currently exists
for our shares. We have applied for approval for quotation of our common stock
on the Nasdaq National Market under the symbol "ACAD." We anticipate that the
initial public offering price will be between $            and $            per
share.
 
                            ------------------------
 
                 INVESTING IN OUR COMMON STOCK INVOLVES RISKS.
                    SEE "RISK FACTORS" BEGINNING ON PAGE 5.
 
                             ---------------------
 

<TABLE>
<CAPTION>
                                                               PER SHARE        TOTAL
                                                              ------------   ------------
<S>                                                           <C>            <C>
Public Offering Price.......................................  $              $
Underwriting Discounts and Commissions......................  $              $
Proceeds to ACADIA Pharmaceuticals Inc......................  $              $
</TABLE>

 
    THE SECURITIES AND EXCHANGE COMMISSION AND STATE SECURITIES REGULATORS HAVE
NOT APPROVED OR DISAPPROVED THESE SECURITIES, OR DETERMINED IF THIS PROSPECTUS
IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL
OFFENSE.
 
    ACADIA Pharmaceuticals Inc. has granted the underwriters a 30-day option to
purchase up to an additional       shares of common stock to cover
overallotments.
 
                            ------------------------
 
ROBERTSON STEPHENS                                    U.S. BANCORP PIPER JAFFRAY
 
               THE DATE OF THIS PROSPECTUS IS             , 2001

<PAGE>
                                     CHART
 
    [Inside front cover: Caption "Linking Genomics and Chemistry" above three
over-lapping circles labeled "Genomics," "Chemistry" and "Biology" with side
caption on left of "Integrated Technology Platform." Downward arrow, captioned
"Drug Discovery," connects the circles to a chart depicting the progress of
ACADIA's programs, which are listed from top to bottom as "Programs": "Glaucoma"
with the subheading "adrenergic," "Chronic Pain" with the subheading "GPCR,"
"Schizophrenia" with the subheadings "m1 muscarinic/dopamine D2" and "5-HT2A
inverse agonist," "Alzheimer's Disease" with the subheading "muscarinic" and
"Glaucoma" with the subheading "muscarinic." To the right of the list of
programs is a chart divided into "Preclinical" and "Development" and with an
arrow for each subheading listed above. The arrows for Glaucoma-adrenergic and
Chronic Pain-GPCR extend through "Preclinical" into "Development" with the
Glaucoma arrow extending further. The arrows for each of the other four
subheadings extend almost entirely through "Preclinical" but do not reach the
threshold for "Development."]

<PAGE>
    YOU SHOULD RELY ONLY ON THE INFORMATION CONTAINED IN THIS PROSPECTUS. WE
HAVE NOT AUTHORIZED ANYONE TO PROVIDE YOU WITH INFORMATION DIFFERENT FROM THAT
CONTAINED IN THIS PROSPECTUS. WE ARE OFFERING TO SELL, AND SEEKING OFFERS TO
BUY, SHARES OF OUR COMMON STOCK ONLY IN JURISDICTIONS WHERE OFFERS AND SALES ARE
PERMITTED. THE INFORMATION CONTAINED IN THIS PROSPECTUS IS ACCURATE ONLY AS OF
THE DATE OF THIS PROSPECTUS, REGARDLESS OF THE TIME OF DELIVERY OF THIS
PROSPECTUS OR OF ANY SALE OF OUR COMMON STOCK. IN THIS PROSPECTUS, "ACADIA," THE
"COMPANY," "WE," "US" AND "OUR" REFER TO ACADIA PHARMACEUTICALS INC., A DELAWARE
CORPORATION.
 
    UNTIL             , 2001, WHICH IS THE 25TH DAY AFTER THE DATE OF THE FINAL
PROSPECTUS RELATED TO THIS OFFERING, ALL DEALERS THAT BUY, SELL OR TRADE OUR
COMMON STOCK, WHETHER OR NOT PARTICIPATING IN THIS OFFERING, MAY BE REQUIRED TO
DELIVER A PROSPECTUS. THIS REQUIREMENT IS IN ADDITION TO THE DEALERS' OBLIGATION
TO DELIVER A PROSPECTUS WHEN ACTING AS UNDERWRITERS AND WITH RESPECT TO THEIR
UNSOLD ALLOTMENTS OR SUBSCRIPTIONS.
 
                            ------------------------
 
                               TABLE OF CONTENTS
 

<TABLE>
<CAPTION>
                                                              PAGE
                                                              ----
<S>                                                           <C>
Summary.....................................................    1
Risk Factors................................................    5
Note Regarding Forward Looking Statements...................   18
Use of Proceeds.............................................   19
Dividend Policy.............................................   19
Capitalization..............................................   20
Dilution....................................................   21
Selected Consolidated Financial Data........................   23

Management's Discussion and Analysis of Financial Condition
  and Results of Operations.................................   24
Business....................................................   29
Management..................................................   49
Related Party Transactions..................................   60
Principal Stockholders......................................   63
Description of Capital Stock................................   66
Shares Eligible for Future Sale.............................   68
United States Tax Consequences to Non-U.S. Holders..........   70
Underwriting................................................   73
Legal Matters...............................................   76
Experts.....................................................   76
Where You Can Find More Information.........................   76
Index to Consolidated Financial Statements..................  F-1
</TABLE>

 
                            ------------------------
 
    "ACADIA" and "R-SAT" are trademarks of ACADIA Pharmaceuticals Inc. This
prospectus also includes trademarks and trade names owned by other parties, and
all other trademarks and trade names mentioned in this prospectus are the
property of their respective owners.
 
                                       i

<PAGE>

                                    SUMMARY
 
    YOU SHOULD READ THE FOLLOWING SUMMARY TOGETHER WITH THE MORE DETAILED
INFORMATION IN THIS PROSPECTUS REGARDING OUR COMPANY, ESPECIALLY THE RISK
FACTORS REGARDING OUR COMPANY AND THE COMMON STOCK BEING SOLD IN THIS OFFERING,
AND OUR FINANCIAL STATEMENTS AND RELATED NOTES, BEFORE DECIDING TO INVEST IN OUR
COMMON STOCK.
 
                             ACADIA PHARMACEUTICALS
 
    We are a genomics-based drug discovery and development company that
efficiently identifies target-specific small molecule drug candidates using our
integrated technology platform. Our proprietary approach integrates genomics,
chemistry and biology to rapidly identify and validate drug targets and discover
chemistries specific to those targets. We have successfully applied our approach
to generate a drug discovery pipeline that currently includes six advanced
programs as well as a number of earlier stage research projects. We have rapidly
advanced two of these programs to development with a collaborator. The first
drug candidate, for glaucoma treatment, is undergoing human testing designed to
provide information on safety and preliminary efficacy in patients, known as a
Phase I/IIa clinical trial. The second drug candidate has been nominated for
development as a novel treatment for chronic pain. We also have four additional
drug candidates in late-stage preclinical testing. We focus on major diseases
that represent some of the largest pharmaceutical markets in the world,
including schizophrenia, Alzheimer's disease, chronic pain and glaucoma.
 
OUR TECHNOLOGY PLATFORM AND DRUG DISCOVERY APPROACH
 
    Our integrated technology platform efficiently and productively links
diverse genomic and chemical information. We use our platform to identify and
validate individual gene products, known as genomic targets, for use as drug
targets. This platform, incorporating our proprietary R-SAT-TM- technology,
allows us to address many classes of potential drug targets, including G-protein
coupled receptors, or GPCRs, cytokine receptors, growth factor receptors,
nuclear receptors, enzymes and neurotransmitter transporters. We also use our
technology platform to discover novel small molecule drug candidates that are
selective for these individual genomic targets. Our discovery expertise combined
with our integrated technology platform has allowed us to discover superior drug
candidates more efficiently than traditional approaches. Since 1997, we have:
 
    - applied our technology to the functional analysis of a wide range of
      genomic targets, incorporating over 250 targets into our platform;
 
    - assembled a large and diverse screening library of more than 700,000
      distinct compounds together with a collaborator;
 
    - developed an ultra high throughput capacity capable of functionally
      screening over 1 million compound/target interactions per week;
 
    - discovered novel specific chemistries in over 200 structural classes for
      35 genomic targets;
 
    - developed a proprietary combinatorial chemistry technique for GPCRs;
 
    - developed a method for screening genomic targets of individual patients
      for variability in their response to drugs;
 
    - validated drug targets for all of our discovery programs and research
      projects together with our collaborators; and
 
    - generated six advanced drug discovery programs, two of which are now in
      development with a collaborator.
 
OUR PROGRAMS
 
    Our programs address major diseases that are not well served by currently
available therapies and that represent significant commercial markets. Our most
advanced program is based on a target-specific drug candidate for the treatment
of glaucoma. In collaboration with Allergan, Inc., we have identified and
validated a specific genomic target that controls pressure within the eye and
have discovered a drug candidate, AGN 195795, that demonstrates a superior
therapeutic profile in animals compared to currently used drugs. AGN 195795 is
currently in a Phase I/IIa clinical trial. We anticipate that the data analysis
from this trial will be completed in the second half of 2001.
 
                                       1

<PAGE>
    Our second most advanced program is based on a novel small molecule drug
candidate, AGN 197075, for the treatment of chronic pain. In collaboration with
Allergan, we identified and validated a specific genomic target and discovered a
novel drug candidate that has been shown to be highly efficacious when
administered orally in animal models. This drug candidate does not exhibit
common side effects of pain drugs including sedation and cardiovascular,
respiratory and gastrointestinal effects. Allergan has nominated this drug
candidate for development and is conducting manufacturing, toxicology and other
studies in preparation for clinical studies.
 
    We have two internal programs in late-stage preclinical development that
address separate genomic targets for treating different groups of schizophrenic
patients. In the first program, we discovered drug candidates that
simultaneously act on two complementary drug targets. These compounds
demonstrate activity when administered orally in animal models of psychosis. In
the second of these programs, we have identified and validated a previously
unknown therapeutic mechanism that is shared by most of the marketed
antipsychotic drugs. We have discovered drug candidates that uniquely target
this mechanism and have shown a superior therapeutic profile in animal models of
psychosis.
 
    We also have an advanced internal preclinical program that focuses on
treating the behavioral disorders associated with Alzheimer's disease. We have
discovered compounds that uniquely target a mechanism that has been implicated
in this disease. These compounds demonstrate activity in animal models of
psychosis believed to be predictive of symptoms observed in Alzheimer's
patients.
 
    Our sixth program is based on a target-specific drug candidate for glaucoma
that addresses a different but complementary drug target than our first glaucoma
program. We have identified and validated with Allergan a genomic target that
controls pressure within the eye. We have discovered compounds that are
selective for this target and show a favorable therapeutic profile in primate
models of glaucoma.
 
    In addition to our six advanced programs, we have several research projects
in which we have identified novel targets and have discovered chemistries
specific for these targets. These projects will serve as starting points for
potential future programs in several areas, including depression, feeding and
obesity, and chronic pain.
 
OUR STRATEGY
 
    The principle elements of our business and scientific strategy include:
 
    - Focus on diseases with large unmet medical needs that are well suited to
      small molecule genomic approaches.
 
    - Build a large and sustainable pipeline of drug candidates to reduce the
      risks inherent in drug discovery and increase the likelihood of commercial
      success.
 
    - Advance selected discovery programs internally through the early clinical
      development stage, which we believe optimizes our position while balancing
      our financial and technical risks.
 
    - Commercialize drug candidates through licensing and development
      collaborations with pharmaceutical and biotechnology companies.
 
    - Commercialize our technology platform through functional genomics
      collaborations to capitalize on our strengths in the areas of target
      validation, lead discovery and pharmacogenomics, which is the study of
      individual genetic variation in the response of patients to drugs.
 
    - Maintain and expand our technology platform leadership through continuous
      internal and external development.
 
                             CORPORATE INFORMATION
 
    We were incorporated in Vermont in 1993 as Receptor Technologies, Inc. In
1997, we reincorporated in Delaware and changed our name to ACADIA
Pharmaceuticals Inc. Our principal executive offices are located at 3911
Sorrento Valley Boulevard, San Diego, California 92121, and our telephone number
at that address is (858) 558-2871. We also have a chemistry research facility
located near Copenhagen, Denmark. Our website is located at
www.acadia-pharm.com. Information contained in our website is not part of this
prospectus.
 
                                       2

<PAGE>
                                  THE OFFERING
 

<TABLE>
<S>                                                          <C>
Common stock offered by us.................................  ______shares
Common stock to be outstanding after this offering.........  ______shares
Use of proceeds............................................  For research and development, capital
                                                             expenditures, working capital and general
                                                             corporate purposes.
Proposed Nasdaq National Market symbol.....................  ACAD
</TABLE>

 
                            ------------------------
 
    The number of shares of common stock to be outstanding after this offering
is based on the number of shares outstanding at November 30, 2000.
 
    The number of shares of common stock to be outstanding after the offering
excludes:
 
    - 1,483,404 shares of common stock issuable upon exercise of options
      outstanding at November 30, 2000, at a weighted average exercise price of
      $0.77 per share;
 
    - 237,257 shares issuable upon exercise of warrants outstanding at
      November 30, 2000, at an exercise price of $12.00 per share; and
 
    - 819,479 shares available for future grant at November 30, 2000 under our
      1997 stock option plan, and an aggregate of approximately 950,000
      additional shares available for future grant under our 2000 equity
      incentive plan, 2000 nonemployee directors' stock option plan and 2000
      employee stock purchase plan, each of which will become effective upon the
      completion of this offering.
 
                            ------------------------
 
    Unless otherwise stated, information in this prospectus is based on the
following assumptions:
 
    - no exercise of the underwriters' overallotment option;
 
    - the conversion of all our outstanding shares of preferred stock into
      8,625,920 shares of common stock upon the closing of this offering; and
 
    - amendments to our certificate of incorporation and bylaws to be effective
      upon completion of this offering.
 
                                       3

<PAGE>
                   SUMMARY CONSOLIDATED FINANCIAL INFORMATION
                 (DOLLARS IN THOUSANDS, EXCEPT PER SHARE DATA)
 
    The following table sets forth summary consolidated financial information
for our company. You should read this information in conjunction with
"Management's Discussion and Analysis of Financial Condition and Results of
Operations" and our financial statements and the related notes included in this
prospectus.
 

<TABLE>
<CAPTION>
                                                                                             NINE MONTHS ENDED
                                                   YEAR ENDED DECEMBER 31,                     SEPTEMBER 30,
                                     ----------------------------------------------------   -------------------
                                       1995       1996       1997       1998       1999       1999       2000
                                     --------   --------   --------   --------   --------   --------   --------
                                                                                                (UNAUDITED)
<S>                                  <C>        <C>        <C>        <C>        <C>        <C>        <C>
CONSOLIDATED STATEMENT OF
  OPERATIONS DATA:
Revenues...........................  $   300    $   438    $   835    $ 1,419    $ 2,238    $ 1,334    $ 2,768
                                     -------    -------    -------    -------    -------    -------    -------
Operating expenses
  Research and development(1)......      264        421      2,295      5,856      7,625      5,582      7,253
  General and administrative(2)....       85        206      1,771      2,487      2,458      1,996      3,989
                                     -------    -------    -------    -------    -------    -------    -------
    Total operating expenses.......      349        627      4,066      8,343     10,083      7,578     11,242
                                     -------    -------    -------    -------    -------    -------    -------
Loss from operations...............      (49)      (189)    (3,231)    (6,924)    (7,845)    (6,244)    (8,474)
Interest income (expense), net.....       (3)        (3)       249        521        400        338        720
                                     -------    -------    -------    -------    -------    -------    -------
Net loss...........................  $   (52)   $  (192)   $(2,982)   $(6,403)   $(7,445)   $(5,906)   $(7,754)
                                     =======    =======    =======    =======    =======    =======    =======
Net loss per share, basic and
  diluted..........................  $ (0.03)   $ (0.13)   $ (1.74)   $ (3.12)   $ (3.57)   $ (2.83)   $ (3.63)
                                     =======    =======    =======    =======    =======    =======    =======
Weighted average shares used in
  computing net loss per share,
  basic and diluted(3).............    1,523      1,523      1,712      2,049      2,087      2,083      2,134
                                     =======    =======    =======    =======    =======    =======    =======
Pro forma net loss per share, basic
  and diluted......................                                              $ (0.96)              $ (0.83)
                                                                                 =======               =======
Weighted average shares used in
  computing pro forma net loss per
  share, basic and diluted(3)......                                                7,780                 9,360
                                                                                 =======               =======
</TABLE>

 

<TABLE>
<CAPTION>
                                                                 SEPTEMBER 30, 2000
                                                              -------------------------
                                                                           PRO FORMA
                                                               ACTUAL    AS ADJUSTED(4)
                                                              --------   --------------
                                                                     (UNAUDITED)
<S>                                                           <C>        <C>
CONSOLIDATED BALANCE SHEET DATA:
Cash, cash equivalents and investment securities............  $ 29,484
Working capital.............................................    27,149
Total assets................................................    33,471
Long-term debt, less current portion........................     4,632
Convertible preferred stock.................................    46,502
Total stockholders' equity (deficit)........................   (20,630)
</TABLE>

 
--------------------------
 
(1) Includes stock-based compensation of $3, $100, $38 and $353 for the years
    ended December 31, 1998 and 1999 and for the nine months ended
    September 30, 1999 and 2000, respectively.
 
(2) Includes stock-based compensation of $49, $6, $5 and $1,856 for the years
    ended December 31, 1998 and 1999 and for the nine months ended
    September 30, 1999 and 2000, respectively.
 
(3) Please see Note 2 of the notes to consolidated financial statements included
    elsewhere in this prospectus for an explanation of the determination of the
    number of shares used in computing per share data.
 
(4) The pro forma as adjusted information in the table reflects the conversion
    of all of our outstanding shares of convertible preferred stock into shares
    of common stock and reflects the sale of             shares of common stock
    offered by us at an assumed initial public offering price of $
    per share, the midpoint of the range on the cover of this prospectus, after
    deducting estimated underwriting discounts and commissions and estimated
    offering expenses payable by us.
 
                                       4

<PAGE>

                                  RISK FACTORS
 
    ANY INVESTMENT IN SHARES OF OUR COMMON STOCK INVOLVES A HIGH DEGREE OF RISK.
YOU SHOULD CONSIDER CAREFULLY THE FOLLOWING INFORMATION ABOUT THESE RISKS,
TOGETHER WITH THE OTHER INFORMATION CONTAINED IN THIS PROSPECTUS, BEFORE YOU
DECIDE TO BUY OUR COMMON STOCK. IF ANY OF THE FOLLOWING RISKS ACTUALLY OCCUR,
OUR BUSINESS, FINANCIAL CONDITION, RESULTS OF OPERATIONS AND FUTURE GROWTH
PROSPECTS WOULD LIKELY SUFFER. IN THESE CIRCUMSTANCES, THE MARKET PRICE OF OUR
COMMON STOCK COULD DECLINE, AND YOU MAY LOSE ALL OR PART OF THE MONEY YOU PAID
TO BUY OUR COMMON STOCK.
 
                         RISKS RELATED TO OUR BUSINESS
 
OUR SUCCESS AS A COMPANY IS UNCERTAIN DUE TO OUR HISTORY OF OPERATING LOSSES AND
THE UNCERTAINTY OF FUTURE PROFITABILITY.
 
    We have not been profitable and have generated substantial operating losses
since we were incorporated in 1993. Our operating losses are due in large part
to the significant research and development costs required to identify and
validate new drug targets and to discover small molecule drug candidates. We
incurred net losses of $3.0 million for the year ended December 31, 1997,
$6.4 million for the year ended December 31, 1998, $7.4 million for the year
ended December 31, 1999 and $7.8 million for the nine months ended
September 30, 2000. At September 30, 2000, our accumulated losses were
approximately $24.6 million. We expect to incur losses for at least the next
several years and expect that these losses will actually increase as we expand
our research and development activities, incur significant preclinical and
clinical development costs and enhance our core technologies. Our losses are
expected to continue even if our research projects successfully identify
potential drug candidates. Currently, our income is generated primarily from
research and milestone payments from collaboration agreements from one
collaborator, interest income and governmental grants. We will need to generate
significant additional revenue to achieve profitability. However, any additional
revenue will depend in large part on our ability, alone or with others, to
successfully research, develop, obtain regulatory clearance for, manufacture,
market and distribute our drug candidates. If the time required to generate
revenues and achieve profitability is longer than anticipated or if we are
unable to obtain necessary capital, we may not be able to fund and continue our
operations.
 
BECAUSE OUR DRUG CANDIDATES ARE IN AN EARLY STAGE OF DEVELOPMENT, THERE IS A
HIGH RISK OF FAILURE.
 
    Drug candidates that appear promising at early stages of development may not
enter clinical development or reach the market for a number of reasons,
including the possibility that the drug candidates will:
 
    - be found ineffective or cause harmful side effects during preclinical
      testing or clinical trials;
 
    - fail to receive the regulatory clearances required to market them as
      drugs;
 
    - be subject to proprietary rights held by others requiring the negotiation
      of a license agreement prior to marketing;
 
    - be difficult or expensive to manufacture on a commercial scale;
 
    - not be developed rapidly enough to compete with drug candidates or other
      treatments commercialized by our competitors; or
 
    - fail to generate market acceptance.
 
    We or our collaborators will need to conduct significant additional
research, preclinical testing and clinical trials before applications with the
FDA are filed for product approval of our drug candidates. Clinical trials are
expensive and have a high risk of failure. If research and testing are not
successful or our drug candidates fail to obtain regulatory approval, we or our
collaborators will be unable to market
 
                                       5

<PAGE>
and sell products derived from our drug candidates. As a result, we may not
receive product royalty revenues and milestone payments and our ability to
continue operations could be jeopardized.
 
BECAUSE DISCOVERING DRUGS THROUGH GENOMICS IS NEW AND SPECULATIVE, IT IS
POSSIBLE THAT OUR INTEGRATED TECHNOLOGY PLATFORM WILL NOT IDENTIFY SUCCESSFUL
DRUG CANDIDATES OR LEAD TO COMMERCIAL PRODUCTS OR SERVICES.
 
    The process of discovering drugs using genomics-based discovery is new and
evolving rapidly. We focus our genomics research primarily on complex diseases
that may be linked to several genes working in combination. We and the rest of
the general scientific and medical community have only a limited understanding
of the role of genes and their products in these diseases. To date, we have not
commercialized any drug candidates, and we may not be successful in doing so in
the future. In addition, relatively few products based on gene discoveries have
been developed and commercialized by others. Successful products will require
significant development and investment, including preclinical testing and
clinical trials, to demonstrate their cost effectiveness prior to regulatory
approval and commercialization. Rapid technological development by us or others
may result in compounds, products or processes becoming obsolete before we
recover our development expenses.
 
    Furthermore, our particular technology platform involves new and unproven
approaches to the identification of drug candidates with therapeutic potential.
These methods may not lead to the discovery of any candidates that will be safe
or effective in humans. In addition, applying our technology to other commercial
areas, such as the study of individual genetic variation in the responses of
patients to drugs, known as pharmacogenomics, may not be successful. In the
future, we may find it necessary to license the technology of others, or
in-license, or acquire additional product candidates to augment the results of
our internal discovery activities, and in-licensed product candidates may not be
available to us or may prove to be unsuccessful. If we are not able to use our
technologies to discover new drugs or products with significant commercial
potential, we will not be able to achieve our objectives or build a sustainable
or profitable business.
 
IF WE FAIL TO OBTAIN THE CAPITAL NECESSARY TO FUND OUR OPERATIONS, WE WILL BE
UNABLE TO SUCCESSFULLY DEVELOP PRODUCTS.
 
    We have consumed substantial amounts of capital since our inception and we
expect to increase our operating expenses over the next several years as we
expand our research and development activities and enhance our core
technologies. Accordingly, we will require significant additional financing in
the future to fund our operations. We do not know whether additional financing
will be available when needed, or that, if available, we will obtain financing
on terms favorable to us and our stockholders. If adequate funds are not
available or are not available on acceptable terms, our ability to fund our
operations, take advantage of opportunities, develop drug candidates and
technologies or otherwise respond to competitive pressures could be
significantly limited. Our future capital requirements will depend on, and could
increase significantly as a result of, many factors, including:
 
    - progress in, and the costs of, our research and development programs;
 
    - the scope, prioritization and number of programs;
 
    - the progress of preclinical and clinical testing;
 
    - our ability to enter into additional collaborations;
 
    - the modification or termination of any of our current or future
      collaborations;
 
    - the time and costs involved in obtaining regulatory approvals;
 
    - the costs involved in obtaining, enforcing and defending patent and other
      intellectual property rights;
 
    - competing technological and market developments;
 
                                       6

<PAGE>
    - the costs of securing manufacturing arrangements for clinical or
      commercial production; and
 
    - our acquisition and development of technologies.
 
IF OUR CURRENT COLLABORATIONS ARE UNSUCCESSFUL OR IF WE ARE UNABLE TO ENTER INTO
ADDITIONAL COLLABORATIONS IN THE FUTURE, OUR RESEARCH AND DEVELOPMENT EFFORTS
COULD BE SIGNIFICANTLY DELAYED.
 
    Our strategy depends upon the formation and sustainability of collaborative
arrangements with third parties. We currently rely, and will continue to rely,
on these arrangements for not only financial resources, but also for expertise
that we expect to need in the future relating to manufacturing, sales and
marketing. To date, we have entered into two collaborative arrangements with
Allergan and one with ArQule, Inc. For the nine months ended September 30, 2000,
approximately 96% of the total revenue we recognized was from our two
collaborations with Allergan. We expect that a similar percentage of our revenue
for the foreseeable future will be generated by collaborations. However, we do
not know if these collaborators will dedicate sufficient resources or if any
development or commercialization efforts by them will be successful. Should a
collaborator fail to develop or commercialize a compound or product to which it
has rights from us, we may not receive any future milestone payments and will
not receive any royalties associated with such compound or product. In addition,
the continuation of our collaborations is dependent on periodic renewal by us
and our collaborators. Our existing collaboration agreements with Allergan may
be terminated before the full term of the collaborations upon a breach or a
change of control or other specified circumstances. We may not be able to renew
these collaborations on acceptable terms, if at all, or negotiate additional
collaborations on acceptable terms, if at all. Finally, we must compete with
other companies for the limited number of opportunities to enter into
collaborative arrangements. As a result, our operating results may fluctuate
significantly depending on the initiation of new collaboration agreements or the
termination of existing collaboration agreements.
 
IF CONFLICTS ARISE WITH OUR COLLABORATORS, THEY MAY ACT IN THEIR SELF INTEREST,
WHICH MAY BE ADVERSE TO OUR INTERESTS.
 
    Conflicts may arise between us and our collaborators, such as conflicts
concerning ownership rights to particular drug candidates. In addition, some of
our collaborators may be conducting multiple product development efforts within
each disease area that is the subject of the collaboration with us. For example,
Allergan currently markets therapeutic products to treat glaucoma and is engaged
in other research programs related to glaucoma that are independent from our two
programs in this therapeutic area. In addition, since our collaborators are
currently conducting, and may in the future conduct, the clinical trials for our
drug candidates, they control the timing of the release of results from these
trials and may decide to delay or withhold the results for their own purposes
even if the results are positive. Generally, in each of our collaborations, we
have agreed not to conduct independently, or with any third party, any research
that is competitive with the research conducted under our collaborations. Our
collaborations may have the effect of limiting the areas of research that we may
pursue, either alone or with others. Our collaborators, however, may develop,
either alone or with others, products in related fields that are competitive
with the products or potential products that are the subject of these
collaborations. Competing products, either developed by the collaborators or to
which the collaborators have rights, may result in their withdrawal of support
for our product candidates.
 
THE PROGRESS AND RESULTS OF PRECLINICAL AND CLINICAL TESTING ARE UNCERTAIN,
WHICH COULD DELAY OUR EFFORTS AND THE EFFORTS OF OUR COLLABORATORS TO
COMMERCIALIZE DRUGS.
 
    Both preclinical and clinical testing are long, expensive and uncertain
processes. It may take several years to complete the preclinical testing and
clinical development necessary to commercialize a drug, and failure can occur at
any stage. Commercialization of product candidates derived from our drug
candidates depends upon successful completion of clinical trials. Interim
results of trials do not
 
                                       7

<PAGE>
necessarily predict final results, and success in preclinical testing and early
clinical trials does not ensure that later clinical trials will be successful. A
number of companies in the pharmaceutical industry, including biotechnology
companies, have suffered significant setbacks in advanced clinical trials, even
after promising results in earlier trials. To date, only one of our drug
candidates has advanced to the early stages of clinical trials. We have never
successfully completed clinical development of any of our drug candidates. In
addition, we do not know whether future clinical trials will begin on time or
whether they will be completed on schedule, or at all. The length of time
necessary to initiate and complete clinical trials varies significantly and may
be difficult to predict. Certain of our activities involve drug testing in small
rodents. The use of animals in research and development and drug candidate
commercialization have been the subject of controversy and adverse publicity.
Animal rights activists could protest against us or damage our preclinical
facilities, which could delay our research and development efforts.
 
    Any drug is likely to produce some toxicities or undesirable side effects in
animals and in humans when administered at sufficiently high doses and/or for
sufficiently long periods of time. Unacceptable toxicities or side effects may
occur at any dose level and at any time in the course of studies of animals
designed to identify unacceptable effects of a drug candidate or during clinical
trials of our potential products. The appearance of any unacceptable toxicity or
side effect could cause our collaborators or regulatory authorities to
interrupt, limit, delay or abort the development of any of our drug candidates
and could ultimately prevent clearance by the required regulatory authorities of
these candidates for any or all targeted indications.
 
WE DEPEND ON THIRD PARTIES TO CONDUCT CLINICAL TRIALS, PERFORM DATA COLLECTION
AND ANALYSIS, AND MARKET AND DISTRIBUTE OUR POTENTIAL PRODUCTS, AND AS A RESULT,
WE MAY FACE ADDITIONAL COSTS AND DELAYING FACTORS OUTSIDE OF OUR CONTROL.
 
    We currently rely on our collaborators, and expect to contract with third
parties in the future, to manufacture drug products, conduct preclinical
studies, including studies regarding biological activity, safety, absorption,
metabolism and excretion of drug candidates, perform clinical trials for safety
and efficacy in humans and market and distribute our potential products. Our
existing collaborations and future agreements for preclinical and clinical
development services will place substantial responsibilities on third parties
for development of our drug candidates which could result in delays in or
termination of development if those parties fail to perform as expected. We may
not be able to maintain any of these existing relationships, or establish new
ones on favorable terms, if at all. We may not be able to enter into replacement
arrangements without undue delays or excessive expenditures. Furthermore, these
collaborators and third parties may not perform as we expect. Our drug discovery
and development costs will increase if there are delays in testing or approvals
or if our collaborators need to perform more or larger clinical trials than
planned. If the delays are significant, our financial results and the commercial
prospects for our drug candidates will be harmed.
 
BECAUSE REGULATORY APPROVAL IS REQUIRED TO MARKET PRODUCTS DERIVED FROM OUR DRUG
CANDIDATES, WE CANNOT PREDICT WHETHER OR WHEN WE OR OUR COLLABORATORS CAN SELL
THOSE PRODUCTS.
 
    The pharmaceutical industry is subject to stringent regulation by a wide
range of authorities. We cannot predict whether regulatory clearance will be
obtained for any product derived from our drug candidates. Even if we obtain
regulatory approval for a drug candidate, the approval may not be obtained in a
timely manner or under technically or commercially feasible conditions.
 
    A pharmaceutical product cannot be marketed in the United States until it
has completed rigorous preclinical testing and clinical trials and an extensive
regulatory clearance process implemented by the FDA. Satisfaction of regulatory
requirements typically takes many years, is dependent upon the type, or
complexity and novelty of the product and requires the expenditure of
substantial resources. Of
 
                                       8

<PAGE>
particular significance are the FDA's requirements covering research and
development, testing, manufacturing, quality control, labeling and promotion of
drugs for human use.
 
    Before beginning clinical trials in humans, we or our collaborators must
submit and receive clearance from the FDA by means of an investigational new
drug application, or IND application. Clinical trials are subject to oversight
by institutional review boards and the FDA and:
 
    - must be conducted in conformance with the FDA's good laboratory practice
      regulations;
 
    - must meet requirements for institutional review board oversight;
 
    - must meet requirements for informed consent by the participants;
 
    - must meet requirements for good clinical and manufacturing practices;
 
    - remain subject to continuing FDA oversight;
 
    - may require large numbers of test subjects; and
 
    - may be suspended by the FDA at any time if it believes that the subjects
      participating in trials are being exposed to unacceptable health risks or
      if the FDA finds deficiencies in the IND application or the conduct of the
      trials.
 
    Before receiving FDA clearance to market a product, we or our collaborators
must demonstrate that the product is safe and effective on the patient
population that will be treated. Data obtained from preclinical and clinical
activities are susceptible to varying interpretations that could delay, limit or
prevent regulatory clearances. Any clinical trial may fail to produce results
satisfactory to the FDA. Negative or inconclusive results or adverse medical
events during a clinical trial could require a clinical trial to be repeated or
a program to be terminated. If regulatory clearance of a product is granted,
this clearance will be limited to those disease states and conditions for which
the product is demonstrated through clinical trials to be safe and efficacious.
We cannot ensure that any compound developed by us, alone or with others, will
prove to be safe and efficacious in clinical trials and will meet all of the
applicable regulatory requirements needed to receive marketing clearance. In
addition, even a successful clinical trial may fail to lead to marketable
products.
 
    Outside the United States, the ability to market a product is contingent
upon receiving a marketing authorization from the appropriate regulatory
authorities. The requirements governing the conduct of clinical trials,
marketing authorization, pricing and reimbursement vary widely from country to
country. At present, foreign marketing authorizations are administered at a
national level, although within the European Community, or EC, registration
procedures are available to companies wishing to market a product in more than
one EC member state. Only after the appropriate regulatory authority is
satisfied that adequate evidence of safety, quality and efficacy has been
presented will it grant a marketing authorization. This foreign regulatory
approval process includes all of the risks associated with FDA clearance
described above.
 
    In addition, access to and use of some human or other tissue samples in our
research and development efforts is subject to government regulation, both in
the United States and abroad. United States and foreign government agencies may
also impose restrictions on the use of data derived from human or other tissue
samples.
 
FAILURE TO ATTRACT, RETAIN AND MOTIVATE SKILLED PERSONNEL WILL DELAY OUR DRUG
DISCOVERY PROGRAMS AND OUR RESEARCH AND DEVELOPMENT EFFORTS.
 
    We are a small company, with under 100 employees, and our success depends on
our continued ability to attract, retain and motivate highly qualified
management and scientific personnel. In particular, our research and drug
discovery programs depend on our ability to attract and retain highly skilled
chemists, biologists and pharmacologists. We may not be able to attract or
retain qualified employees in the future due to the intense competition for
qualified personnel among biotechnology
 
                                       9

<PAGE>
and other technology based businesses, particularly in the San Diego, California
area. If we are not able to attract and retain the necessary personnel to
accomplish our business objectives, we may experience constraints that will
impede significantly the achievement of our research and development objectives
and our ability to meet the demands of our collaborators in a timely fashion. In
addition, we will need to hire additional personnel as we continue to expand our
research and development activities. Competition for experienced scientists and
other technical personnel from numerous companies and academic and other
research institutions may limit our ability to attract and retain qualified
personnel on acceptable terms. In addition, all of our employees are at will
employees, which means that any employee may quit at any time. In particular, if
we lose Mark R. Brann, Ph.D., our founder, President, Chief Scientific Officer
and a director, or Uli Hacksell, Ph.D., our Chief Executive Officer and a
director, we may not be able to find a suitable replacement and our business may
be harmed as a result.
 
IF OUR COMPETITORS DEVELOP AND MARKET PRODUCTS THAT ARE MORE EFFECTIVE THAN
PRODUCTS DERIVED FROM OUR DRUG CANDIDATES, OUR COMMERCIAL OPPORTUNITY WILL BE
REDUCED OR ELIMINATED.
 
    The pharmaceutical and biotechnology industries are characterized by rapid
technological change, and the area of gene research is a rapidly evolving field.
Our future success will depend on our ability to maintain a competitive position
with respect to technological advances. Rapid technological development by
others may result in our technology platform becoming obsolete. Our commercial
opportunity will be reduced or eliminated if our competitors develop and market
products that are more effective, have fewer side effects or are less expensive
than products we hope to derive from our drug candidates.
 
    We face intensifying competition from pharmaceutical and biotechnology
companies that are pursuing drugs that are competitive with prospective product
candidates derived from our drug candidates. Our competitors include fully
integrated pharmaceutical companies and biotechnology companies, including our
collaborators, that currently have drug and target discovery efforts. In
addition, companies pursuing different but related fields represent substantial
competition. Our ability to compete successfully will depend on our ability,
alone or together with our collaborators, to develop drug candidates that reach
the market in a timely manner and are technologically superior to, and/or are
less expensive than, other products on the market. However, many of the
organizations competing with us have substantially greater capital resources,
larger research and development staffs and facilities, greater experience in
drug development and in obtaining regulatory approvals and greater marketing
capabilities than we do.
 
    Universities and public and private research institutions are also
competitors. While these organizations primarily have educational objectives,
they may develop proprietary technology and acquire patents that we may need for
the development of our drug products. We may attempt to license this proprietary
technology, if available. These licenses may not be available to us on
acceptable terms, if at all.
 
    With respect to our drug discovery programs, other companies may have
product candidates in clinical trials to treat each of the diseases for which we
are seeking to discover and develop product candidates. These competing
potential drugs may be further advanced in development than are any of the
potential products derived from our drug candidates and may result in effective,
commercially successful products. Even if our collaborators or we are successful
in developing effective drugs from our drug candidates, those drugs may not
compete effectively with our competitor's drugs. Our competitors may succeed in
developing and marketing products that are more effective than those that we may
develop, alone or with our collaborators. If our competitors reach the market
with competing drugs before we do, we may experience difficulty gaining market
share over their established products.
 
                                       10

<PAGE>
OUR ABILITY TO COMPETE MAY DECLINE IF WE DO NOT ADEQUATELY PROTECT OUR
PROPRIETARY RIGHTS.
 
    Our commercial success will depend in part on our obtaining, securing and
defending patent protection on our technologies and drug candidates. We will be
able to protect our proprietary technologies and drug candidates from
unauthorized use by third parties only to the extent that our technologies and
drug candidates are covered by valid and enforceable patents or are effectively
maintained as trade secrets. If we do not protect our intellectual property
adequately, competitors may be able to use our technologies and thereby erode
our competitive advantage. The patent positions of pharmaceutical and
biotechnology companies can be highly uncertain and involve complex legal and
factual questions. For example, some of our patent applications will cover gene
sequences and their products and the uses of those gene sequences and products.
The Human Genome Project, as well as the genomics efforts of many companies and
institutions, have sequenced the human and other genomes and deposited partial
and full length sequences in public databases or included those sequences in
patent applications that are not yet publicly available. These public
disclosures and patent applications may limit the scope of our claims or make
unpatentable subsequent patent applications on full length genes and the uses of
those genes and their products. No consistent policy regarding the breadth of
claims allowed in biotechnology patents has emerged to date. Accordingly, we
cannot predict the breadth of claims that the U.S. Patent and Trademark Office
will allow in the future in our own or in other companies' patents. In addition,
changes in or different interpretations of patent laws in the United States and
foreign countries may permit others to use our discoveries or to develop and
commercialize our technology and products without providing any compensation to
us. The degree of future protection for our proprietary rights is uncertain due
to a number of factors, including:
 
    - we may not have been the first to file patent applications for the
      technologies we rely upon;
 
    - others may independently develop similar or alternative technologies or
      duplicate any of our technologies;
 
    - our disclosures in patent applications may not be sufficient to meet the
      statutory requirements for patentability in all cases;
 
    - any of our pending patent applications may not result in issued patents;
 
    - we may not seek or obtain patent protection in all countries that will
      eventually provide a significant business opportunity;
 
    - any patents issued to us or our collaborators may not provide a basis for
      commercially viable products or may not provide us with any competitive
      advantages or may be challenged by third parties;
 
    - our proprietary technologies may not be patentable; or
 
    - the patents of others may have an adverse effect on our ability to do
      business.
 
    Any conflicts resulting from third party patent applications and patents
could significantly reduce the coverage of the patents owned, optioned by or
licensed to us or our collaborators and limit our ability or that of our
collaborators to obtain meaningful patent protection. If patents are issued to
third parties that contain competitive or conflicting claims, we and our
collaborators may be legally prohibited from pursuing research, development or
commercialization of potential products or be required to obtain licenses to
these patents or to develop or obtain alternative technology. We may not have
rights under some patents or patent applications related to our proposed
products, processes or services. Third parties may own or control these patents
and patent applications in the United States and abroad. Therefore, in some
cases, to develop, manufacture, sell or import some of our proposed products,
processes or services, we or our alliance partners may choose to seek, or be
required to seek, licenses under third party patents issued in the United States
and abroad or those which might issue from United States and foreign patent
applications. In that event, we would be required to pay license fees or
royalties or both to the licensor. If licenses are not available to us on
acceptable terms, we or our collaborators may not be able to develop,
manufacture, sell or import these products, processes or services.
 
                                       11

<PAGE>
    In addition, patent law outside the United States is uncertain and in many
countries is currently undergoing review and revision. The laws of some
countries do not protect intellectual property rights to the same extent as
United States laws, and those countries may lack adequate rules and procedures
for defending intellectual property rights that are granted. As a result, many
companies have encountered significant problems in obtaining and defending their
proprietary rights abroad. It may be necessary or useful for us to participate
in proceedings to determine the validity of our and our competitors' foreign
patents, which could result in substantial costs and would divert our efforts
and attention from other aspects of our business.
 
    In-licensed technology may become important to some aspects of our business.
We generally will not control the patent prosecution, maintenance or enforcement
of in-licensed technology. Accordingly, we will be unable to exercise the same
degree of control over this intellectual property as we do over our internally
developed technology. Moreover, some of our academic institution licensors,
research collaborators and scientific advisors have rights to publish data and
information to which we have rights. If we cannot maintain the confidentiality
of our technology and other confidential information in connection with our
collaborations, then our ability to receive patent protection or protect our
proprietary information will be impaired.
 
A DISPUTE CONCERNING THE INFRINGEMENT OR MISAPPROPRIATION OF OUR PROPRIETARY
RIGHTS OR THE PROPRIETARY RIGHTS OF OTHERS COULD BE TIME CONSUMING AND COSTLY
AND COULD DELAY OUR RESEARCH AND DEVELOPMENT EFFORTS.
 
    Our success depends partly upon our ability to avoid infringing or
misappropriating the proprietary rights of others. We could incur substantial
costs in litigation if we are required to defend against patent suits brought by
third parties or if we initiate these suits. Others may have filed and in the
future are likely to file patent applications covering assays, genes, gene
products or therapeutic products that are similar or identical to ours. We
cannot assure you that any patent application will not have priority over patent
applications filed by us. Any legal action against our collaborators or us
claiming damages and seeking to enjoin commercial activities relating to the
affected products and processes could, in addition to subjecting us to potential
liability for damages, require our collaborator or us to obtain a license to
continue to manufacture or market the affected products and processes. We cannot
predict whether we or our collaborators would prevail in any of these actions or
that any license required under any of these patents would be made available on
commercially acceptable terms, if at all.
 
    We believe that there is significant litigation in the industry regarding
patent and other intellectual property rights. If we become involved in
litigation initiated by a third party, it could consume a substantial portion of
our managerial and financial resources. Furthermore, parties making claims
against us may be able to obtain injunctive or other equitable relief that may
effectively block our ability to further develop, commercialize and sell
products. Any litigation or administrative proceedings that we may become
involved in would likely be costly, whether we win or lose. In the event of a
successful claim of infringement, we may be required to pay damages and obtain
one or more licenses from third parties. We may not be able to obtain necessary
licenses at a reasonable cost, if at all. In that event, we could encounter
delays in product introductions while we attempt to develop alternate methods or
products or be prevented from commercializing current or future products.
Similarly, third parties may infringe on or misappropriate our proprietary
rights, and we may have to institute costly legal action against them to protect
our intellectual property rights. We may not be able to afford the costs of
enforcing our intellectual property rights against these third parties.
 
    In addition, like many biotechnology companies, we may from time to time
hire scientific personnel formerly employed by other companies involved in one
or more areas similar to the activities conducted by us. We or these individuals
may be subject to allegations of trade secret misappropriation or other similar
claims as a result of their prior affiliations. Resolving those claims could
also result in significant expenditures of both the time of personnel and our
financial resources.
 
                                       12

<PAGE>
CONFIDENTIALITY AGREEMENTS WITH EMPLOYEES AND OTHERS MAY NOT ADEQUATELY PREVENT
DISCLOSURE OF OUR TRADE SECRETS AND OTHER PROPRIETARY INFORMATION.
 
    In order to protect our proprietary technology and processes, we also rely
in part on trade secret protection for our confidential and proprietary
information. However, trade secrets are difficult to protect. Our policy is to
execute confidentiality agreements with our employees and consultants upon the
commencement of an employment or consulting arrangement with us. These
agreements generally require that all confidential information developed by the
individual or made known to the individual by us during the course of the
individual's relationship with us be kept confidential and not disclosed to
third parties. These agreements also generally provide that inventions conceived
by the individual in the course of rendering services to us shall be our
exclusive property. While we require employees, academic collaborators and
consultants to enter into confidentiality agreements, we cannot assure you that:
 
    - proprietary information will not be disclosed;
 
    - others will not independently develop substantially equivalent proprietary
      information and techniques;
 
    - others will not gain access to our trade secrets or disclose this
      technology;
 
    - these obligations of confidentiality will be honored; or
 
    - we can meaningfully protect our rights to proprietary information.
 
    Costly and time consuming litigation could be necessary to enforce and
determine the scope of our proprietary rights, and failure to obtain or maintain
trade secret protection could adversely affect our competitive business
position.
 
WE EXPECT THAT OUR RESULTS OF OPERATIONS WILL FLUCTUATE, WHICH MAY MAKE IT
DIFFICULT TO PREDICT OUR FUTURE PERFORMANCE.
 
    Our quarterly operating results have fluctuated in the past and are likely
to do so in the future. A large portion of our expenses, including expenses for
personnel, facilities, equipment and contracted research, is relatively fixed.
In addition, we plan to significantly increase operating expenses in the near
term as we expand our internal research and development activities. Failure to
achieve anticipated levels of revenue could significantly harm our operating
results for a particular fiscal period. Due to the possibility of fluctuations
in our revenue and expenses, we believe that period to period comparisons of our
operating results are not a good indication of our future performance. Some of
the factors that could cause our operating results to fluctuate from period to
period include:
 
    - termination or reduction in the scope of our collaborations;
 
    - the success rate of our collaborators' discovery and development efforts
      associated with milestones and royalties;
 
    - our ability to enter into new agreements with collaborators or to extend
      the terms of our existing corporate collaboration agreements;
 
    - our ability to satisfy all applicable regulatory requirements;
 
    - the rate of expansion of our internal research and development efforts and
      related expenses; and
 
    - general and industry specific economic conditions that may affect our
      collaborators' research and development expenditures.
 
IF OUR STRATEGIC DECISIONS DO NOT YIELD COMMERCIALLY VIABLE PRODUCTS, WE MAY NOT
ACHIEVE PROFITABILITY.
 
    While we believe that our integrated drug discovery approach can be applied
to many types of diseases, due to our limited financial and managerial
resources, we have made strategic decisions to focus our current resources on
six programs that address four specific diseases:
 
    - schizophrenia;
 
                                       13

<PAGE>
    - Alzheimer's disease;
 
    - chronic pain; and
 
    - glaucoma.
 
This decision requires us to forego potential opportunities with respect to
other diseases. We may not successfully select diseases or those drug candidates
with the most potential for commercial development. Our efforts may not produce
viable commercial products and we may be precluded from other, more profitable
opportunities.
 
ANY CLAIMS RELATING TO IMPROPER HANDLING, STORAGE OR DISPOSAL OF THE BIOLOGICAL
AND HAZARDOUS MATERIALS USED IN OUR BUSINESS COULD BE COSTLY AND DELAY OUR
RESEARCH AND DEVELOPMENT EFFORTS.
 
    Our research and development activities involve the controlled use of
potentially harmful hazardous materials, including biological materials,
chemicals and various radioactive compounds. We cannot completely eliminate the
risk of accidental contamination or injury from the use, storage, handling or
disposal of these materials. In the event of contamination or injury, we could
be held liable for damages that result, and any liability could exceed our
resources. We are subject to federal, state and local laws and regulations
governing the use, storage, handling and disposal of these materials and
specified waste products. The cost of compliance with these laws and regulations
could be significant, and current or future environmental regulations may impair
our research, development or production efforts.
 
WE MAY BE SUED FOR PRODUCT LIABILITY AND COULD FACE SUBSTANTIAL LIABILITIES THAT
EXCEED OUR RESOURCES.
 
    Researching, developing and commercializing drug products entail significant
product liability risks. The use of products developed by us, alone or with our
collaborators, in clinical trials and the commercial sale of those products may
expose us and our collaborators to liability claims. These claims may be made
directly by consumers or by our collaborators or others selling these products.
We may be held liable if any drug we develop, or any drug which is developed
with the use of any of our technologies, causes injury or is found otherwise
unsuitable during testing, manufacturing, marketing or sale. We currently have
no product liability insurance for clinical trials. When and if we attempt to
obtain product liability insurance for clinical trials, this insurance may be
prohibitively expensive, or may not fully cover our potential liabilities.
Inability to obtain sufficient insurance coverage at an acceptable cost or
otherwise to protect against potential product liability claims could prevent or
inhibit the commercialization of products developed by us or our collaborators.
If we are sued for any injury caused by our products, our liability could exceed
our total assets.
 
WE MAY ENCOUNTER DIFFICULTIES MANAGING OUR GROWTH, WHICH COULD ADVERSELY AFFECT
OUR RESULTS OF OPERATIONS.
 
    We will need to expand and effectively manage our operations and facilities
in order to successfully complete our existing collaborative agreements,
facilitate additional collaborations and pursue future internal research,
development and commercialization efforts. We increased the number of our
employees from 69 at December 31, 1999 to 89 at November 30, 2000, and, based on
the availability of funding, we expect to significantly increase our rate of
growth to meet our strategic objectives. If we continue to grow, it is possible
that the number and skills of management and scientific personnel, systems and
facilities currently in place may not be adequate. Our ability to effectively
manage our operations, growth, and various projects requires us to continue to
improve our operational, financial and management controls, reporting systems
and procedures and to attract and retain sufficient numbers of talented
employees. We may not be able to successfully implement these tasks on a larger
scale and, accordingly, may not achieve our research, development and
commercialization goals.
 
                                       14

<PAGE>
IF ETHICAL AND OTHER CONCERNS SURROUNDING THE USE OF GENETIC INFORMATION BECOME
WIDESPREAD, WE MAY HAVE LESS DEMAND FOR OUR PRODUCTS.
 
    We have entered into a collaboration agreement designed to provide
pharmacogenomic services to pharmaceutical companies using our integrated
technology platform, including genetic testing. Genetic testing has raised
ethical issues regarding confidentiality and the appropriate uses of the
resulting information. For these reasons, governmental authorities may call for
limits on or regulation of the use of genetic testing or prohibit testing for
genetic predisposition to selected conditions. Any of these scenarios could
reduce the potential markets for our pharmacogenomic services.
 
WE FACE ADMINISTRATIVE CHALLENGES IN COORDINATING THE OPERATIONS OF OUR DANISH
SUBSIDIARY AND OUR ACTIVITIES IN CALIFORNIA.
 
    Our subsidiary in Denmark, ACADIA Pharmaceuticals A/S, employs approximately
29% of our total personnel, and is engaged in research and development
activities with primary responsibility for combinatorial, medicinal and
analytical chemistry. Our principal executive offices, however, are located in
California. The additional administrative expense required to monitor and
coordinate activities in both Denmark and California could divert management
resources from other important endeavors and, in turn, delay any development and
commercialization efforts. In addition, currency fluctuations involving our
Danish operations may cause foreign currency translation gains and losses. We
cannot predict the effect of such exchange rate fluctuations on our combined
operations and we do not engage in currency hedging transactions.
 
                         RISKS RELATED TO THIS OFFERING
 
OUR STOCK PRICE MAY BE VOLATILE AND YOUR INVESTMENT IN OUR STOCK COULD DECLINE
  IN VALUE.
 
    The market prices for securities of biotechnology companies in general, and
genomics companies specifically have been highly volatile and may continue to be
highly volatile in the future. The following factors, in addition to other risk
factors described in this section, may have a significant impact on the market
price of our common stock:
 
    - market conditions related to the genomics, biotechnology and
      pharmaceutical industries or the market in general;
 
    - announcements of technological innovations or new commercial products by
      our competitors or us;
 
    - developments concerning proprietary rights, including patents;
 
    - developments concerning our collaborations;
 
    - publicity regarding actual or potential medical results relating to
      products under development by our competitors or us;
 
    - public concern as to genetic testing or the safety of drugs and drug
      delivery techniques;
 
    - regulatory developments in the United States and foreign countries;
 
    - securities analysts' recommendations;
 
    - litigation;
 
    - economic and other external factors or other disasters or crises; or
 
    - period to period fluctuations in financial results.
 
                                       15

<PAGE>
OUR MANAGEMENT HAS BROAD DISCRETION ON THE USE OF THE PROCEEDS FROM THIS
OFFERING, AND WE MAY ALLOCATE THE PROCEEDS IN WAYS THAT YOU AND OTHER
STOCKHOLDERS MAY NOT APPROVE.
 
    Our management will have significant flexibility in applying the net
proceeds of this offering and could use these proceeds for corporate purposes
that do not increase our profitability or our market value, or in ways with
which our stockholders may not agree. We currently intend to use the proceeds of
this offering and our existing cash balances to fund research and development
expenses, capital expenditures, working capital and general corporate purposes.
We may also use proceeds for acquisitions or investments in complementary
businesses, technologies or products. Pending these expected uses, the proceeds
of the offering will be invested in short-term investment grade interest-
bearing securities that may lose value. Our management may allocate the net
proceeds among these purposes as it determines necessary. In addition, market
factors may require our management to allocate all or a portion of the net
proceeds for other purposes. You may not agree with the manner in which our
management ultimately uses the net proceeds of this offering. Accordingly, you
will be relying on the judgment of our management team with regard to the
application of the net proceeds of this offering.
 
IF OUR OFFICERS, DIRECTORS AND LARGEST STOCKHOLDERS CHOOSE TO ACT TOGETHER, THEY
MAY BE ABLE TO CONTROL OUR MANAGEMENT AND OPERATIONS, ACTING IN THEIR BEST
INTERESTS AND NOT NECESSARILY THOSE OF OTHER STOCKHOLDERS.
 
    Following completion of this offering, our directors, executive officers and
principal stockholders and their affiliates will beneficially own approximately
      % of our common stock, based on their beneficial ownership at
November 30, 2000. Accordingly, they collectively will have the ability to
affect the election of all of our directors and to affect the outcome of most
corporate actions requiring stockholder approval, such as amendments to our
certificate of incorporation, going private transactions and other significant
corporate events. They may exercise this ability in a manner that advances their
best interests and not necessarily those of other stockholders. This
concentration of control may depress our stock price.
 
THERE IS NO PRIOR MARKET FOR OUR COMMON STOCK AND YOU MAY NOT BE ABLE TO RESELL
YOUR SHARES AT OR ABOVE THE INITIAL OFFERING PRICE.
 
    Prior to this offering, there has been no public market for shares of our
common stock. An active, liquid trading market may not develop following
completion of this offering, or if developed, may not be maintained. We will
determine the initial public offering price for the shares through negotiations
between us and the representatives of the underwriters. This price may not be
indicative of prices that will prevail in the future in the trading market.
Among the factors to be considered in determining the initial public offering
price of the common stock, in addition to prevailing market conditions, will be:
 
    - estimates of our business potential and earnings prospects;
 
    - an assessment of our management; and
 
    - the consideration of the above factors in relation to market valuations of
      companies in related businesses.
 
    Due to the uncertainty in determining the initial public offering price and
other risk factors described in this section, the market price of the common
stock may decline below the initial public offering price, and you may not be
able to resell your shares at or above this price.
 
                                       16

<PAGE>
IF OUR STOCKHOLDERS SELL SUBSTANTIAL AMOUNTS OF OUR COMMON STOCK AFTER THE
PUBLIC OFFERING, THE MARKET PRICE OF OUR COMMON STOCK MAY FALL.
 
    If our stockholders sell substantial amounts of our common stock, including
shares issued upon the exercise of outstanding options and warrants, the market
price of our common stock may fall. These sales also might make it more
difficult for us to sell equity or equity related securities in the future at a
time and price that we deem appropriate. After completion of the public
offering, we will have       outstanding shares of common stock.
 
    The number of shares of common stock available for sale in the public market
is limited by restrictions under federal securities laws and under agreements
into which substantially all of our stockholders have entered with the
underwriters or with us. The lockup agreements with the underwriters restrict
those stockholders from selling, pledging or otherwise disposing of their shares
for a period of 180 days after the date of this prospectus without the prior
written consent of the underwriters. However, the underwriters may, in their
sole discretion, release all or any portion of the common stock from the
restrictions of the lockup agreements.
 
    We intend to file a registration statement on Form S-8 covering an aggregate
of       shares issuable upon exercise of options to purchase common stock and
common stock reserved for issuance under our stock plans in connection with this
offering.
 
ANTI-TAKEOVER PROVISIONS IN OUR CHARTER DOCUMENTS AND UNDER DELAWARE LAW MAY
MAKE AN ACQUISITION OF US, WHICH MAY BE BENEFICIAL TO OUR STOCKHOLDERS, MORE
DIFFICULT.
 
    Provisions of our amended and restated certificate of incorporation and
bylaws, as well as provisions of Delaware law, could make it more difficult for
a third party to acquire us, even if doing so would benefit our stockholders.
These provisions:
 
    - establish that members of the board of directors may be removed only for
      cause upon the affirmative vote of stockholders owning at least a majority
      of our capital stock;
 
    - authorize the issuance of "blank check" preferred stock that could be
      issued by our board of directors to increase the number of outstanding
      shares and prevent or delay a takeover attempt;
 
    - limit who may call a special meeting of stockholders;
 
    - prohibit stockholder action by written consent, thereby requiring all
      stockholder actions to be taken at a meeting of our stockholders;
 
    - establish advance notice requirements for nominations for election to the
      board of directors or for proposing matters that can be acted upon at
      stockholder meetings; and
 
    - provide for a board of directors with staggered terms.
 
    In addition, Section 203 of the Delaware General Corporation Law may
discourage, delay or prevent a third party from acquiring us.
 
THE PUBLIC OFFERING WILL CAUSE IMMEDIATE AND SUBSTANTIAL DILUTION TO YOUR
INVESTMENT.
 
    Purchasers in the public offering will experience immediate and substantial
dilution in the net tangible book value of the common stock from the initial
public offering price. Because we expect the offering price to be substantially
higher than the net tangible book value per share of the common stock, if you
purchase shares in this offering, you will incur dilution in the net tangible
book value per share of your shares of $      based on the initial public
offering price of $      , the midpoint of the range on the cover of this
prospectus. In the past, we issued options and warrants to acquire capital stock
at prices below the initial public offering price of common stock in this
offering. As a result, there likely will be further dilution to investors upon
exercise of these options and warrants.
 
                                       17

<PAGE>
                   NOTE REGARDING FORWARD LOOKING STATEMENTS
 
    This prospectus may contain forward looking statements. The forward looking
statements are contained principally in the sections entitled "Summary,"
"Management's Discussion and Analysis of Financial Condition and Results of
Operations" and "Business." These statements involve known and unknown risks,
uncertainties and other factors which may cause our actual results, performance
or achievements to be materially different from any future results, performances
or achievements expressed or implied by the forward looking statements. Forward
looking statements include, but are not limited to statements about:
 
    - the progress of clinical trials involving our drug candidates;
 
    - the progress of our research and development programs;
 
    - the benefits to be derived from relationships with our collaborators;
 
    - the receipt of regulatory clearances and approvals;
 
    - our estimates of future revenue and profitability; and
 
    - our estimates regarding our capital requirements and our need for
      additional financing.
 
    In some cases, you can identify forward looking statements by terms such as
"may," "will," "should," "could," "would," "expects," "plans," "anticipates,"
"believes," "estimates," "projects," "predicts," "potential" and similar
expressions intended to identify forward looking statements. These statements
reflect our current views with respect to future events and are based on
assumptions and subject to risks and uncertainties. Given these uncertainties,
you should not place undue reliance on these forward looking statements. We
discuss many of these risks in this prospectus in greater detail under the
heading "Risk Factors." Also, these forward looking statements represent our
estimates and assumptions only as of the date of this prospectus.
 
    You should read this prospectus and the documents that we reference in this
prospectus completely and with the understanding that our actual future results
may be materially different from what we expect. We qualify all of our forward
looking statements by these cautionary statements.
 
    You should rely only on the information contained in this prospectus. We
have not authorized anyone to provide you with different information. We are not
making an offer of these securities in any state where the offer is not
permitted. You should not assume that the information provided by this
prospectus is accurate as of any date other than the date on the front of this
prospectus.
 
                                       18

<PAGE>

                                USE OF PROCEEDS
 
    The proceeds from the sale of             shares of common stock we are
offering are estimated to be approximately $      million, approximately
$      million if the underwriters' overallotment option is exercised in full,
after deducting underwriting discounts and commissions and our estimated
offering expenses and based on an assumed initial public offering price of
$    per share, the mid-point of the range on the front cover of this
prospectus.
 
    We intend to use the net proceeds from this offering to fund research and
development activities, including research expenses and preclinical and clinical
development expenses associated with our internal drug discovery programs, and
capital expenditures. We expect to use any remaining net proceeds for working
capital and general corporate purposes. We may also use a portion of the net
proceeds to acquire or invest in complementary businesses or products or to
obtain the right to use complimentary technologies; however, we have no present
plans, agreements or commitments and are not currently engaged in any
negotiations with respect to any such transactions. Pending these uses, the
proceeds of the offering will be invested in short-term investment grade
interest bearing securities.
 
    The amounts and timing of our actual expenditures will depend significantly
upon a number of factors, including the amount and timing of revenues from our
current or future collaborators. Pending use of the net proceeds for the above
purposes, we intend to invest these funds in short-term, interest bearing
investment grade securities.
 

                                DIVIDEND POLICY
 
    We have never paid or declared cash dividends on our capital stock. We
currently intend to retain future earnings, if any, for use in the expansion and
operation of our business and do not anticipate paying any cash dividends in the
foreseeable future.
 
                                       19

<PAGE>

                                 CAPITALIZATION
 
    The following table sets forth our capitalization at September 30, 2000:
 
    - on an actual basis derived from our unaudited consolidated financial
      statements;
 
    - on a pro forma basis to give effect to the conversion of all of our
      outstanding shares of convertible preferred stock into an aggregate of
      8,625,920 shares of common stock; and
 
    - on a pro forma as adjusted basis to also give effect to the sale of
                  shares of common stock offered hereby at an assumed initial
      offering price of $      per share, the midpoint of the range on the cover
      of this prospectus, after deducting underwriting discounts and commissions
      and estimated offering expenses.
 
    You should read this table in conjunction with the consolidated financial
statements and the notes to those statements and the other financial information
included elsewhere in this prospectus.
 

<TABLE>
<CAPTION>
                                                                        SEPTEMBER 30, 2000
                                                         -------------------------------------------------
                                                                                               PRO FORMA
                                                          ACTUAL           PRO FORMA          AS ADJUSTED
                                                         ---------         ----------         ------------
                                                                            (UNAUDITED)
                                                          (IN THOUSANDS, EXCEPT SHARE AND PER SHARE DATA)
<S>                                                      <C>               <C>                <C>
Long-term obligations, less current portion............  $  4,632           $  4,632             $  4,632
                                                         --------           --------             --------
Convertible preferred stock, $0.01 par value:
  10,019,067 shares authorized, 8,625,920 shares issued
  and outstanding, actual; 5,000,000 shares authorized,
  no shares issued and outstanding, pro forma and pro
  forma as adjusted....................................    46,502                 --                   --
                                                         --------           --------             --------
Stockholders' equity (deficit):
  Common stock, $0.0001 par value: 14,218,712 shares
    authorized, 2,145,962 shares outstanding, actual;
    10,771,882 shares issued and outstanding, pro
    forma; 50,000,000 shares authorized,       shares
    issued and outstanding, pro forma as adjusted......        --                  1
  Additional paid-in capital...........................     4,792             51,293
  Accumulated deficit..................................   (24,559)           (24,559)             (24,559)
  Unearned stock-based compensation....................    (1,260)            (1,260)              (1,260)
  Accumulated other comprehensive income...............       397                397                  397
                                                         --------           --------             --------
    Total stockholders' equity (deficit)...............   (20,630)            25,872
                                                         --------           --------             --------
      Total capitalization.............................  $ 30,504           $ 30,504             $
                                                         ========           ========             ========
</TABLE>

 
    The number of shares of common stock outstanding at September 30, 2000 does
not include:
 
    - 237,257 shares of common stock issuable upon exercise of outstanding
      warrants at an exercise price of $12.00 per share;
 
    - 1,310,654 shares of common stock issuable upon exercise of options
      outstanding at September 30, 2000 at a weighted average exercise price of
      $0.71 per share; and
 
    - 303,729 shares available for future grant at September 30, 2000 under our
      1997 stock option plan.
 
    From October 1, 2000 to November 30, 2000, we issued an aggregate of 11,500
shares upon the exercise of options at a weighted average price of $0.67 per
share. In addition, from October 1, 2000 to November 30, 2000, we granted
190,000 options to purchase common stock at a weighted average exercise price of
$1.16 per share, and 5,750 options to purchase common stock at a weighted
average exercise price of $0.48 per share were forfeited.
 
                                       20

<PAGE>
                                    DILUTION
 
    Our net tangible book value at September 30, 2000 was $25,871,600. Net
tangible book value per share is determined by dividing the net tangible book
value, total tangible assets less total liabilities, by the number of
outstanding shares of common stock at that date. Assuming the conversion of all
outstanding shares of preferred stock into shares of common stock, our pro forma
net tangible book value at September 30, 2000 was approximately $2.40 per share
of common stock. Without taking into account any other changes in pro forma net
tangible book value other than the sale of             shares of our common
stock in this offering at an assumed initial public offering price of $    per
share, the mid-point of the range on the cover of this prospectus, and, after
deducting underwriting discounts and commissions and our estimated offering
expenses, the pro forma as adjusted net tangible book value at September 30,
2000 would be $            , or $      per share. Assuming the completion of
this offering, there will be an immediate increase in net tangible book value to
existing stockholders of $      per share and an immediate dilution to new
investors of $      per share. The following table illustrates the per share
dilution to new investors:
 

<TABLE>
<S>                                                           <C>     <C>
Assumed initial public offering price per share.............          $
  Pro forma net tangible book value per share at
    September 30, 2000......................................  $2.40
  Pro forma increase in net tangible book value per share
    attributable to new investors...........................
Pro forma as adjusted net tangible book value per share,
  after offering............................................
                                                                      -----
Pro forma dilution per share to new investors...............          $
                                                                      =====
</TABLE>

 
    If the underwriters exercise their overallotment option in full, there will
be an increase in pro forma net tangible book value to $    per share to
existing stockholders and an immediate dilution in pro forma net tangible book
value of $    to new investors.
 
    The following table summarizes on a pro forma basis at September 30, 2000
the differences between the existing stockholders and new investors with respect
to the number of shares of common stock purchased from us, the total
consideration paid and the average price per share paid, assuming the conversion
of all outstanding shares of preferred stock into shares of common stock:
 

<TABLE>
<CAPTION>
                            SHARES PURCHASED          TOTAL CONSIDERATION
                          ---------------------      ----------------------      AVERAGE PRICE
                            NUMBER     PERCENT         AMOUNT      PERCENT         PER SHARE
                          ----------   --------      -----------   --------      -------------
<S>                       <C>          <C>           <C>           <C>           <C>
Existing stockholders...  10,771,882        %        $49,121,600        %           $ 4.56
New investors...........
                          ----------     ---         -----------     ---
    Total...............                 100%        $               100%
                          ==========     ===         ===========     ===
</TABLE>

 
    If the underwriters exercise their overallotment option in full, our
existing stockholders would own    % and our new investors would own    % of the
total number of shares of our common stock outstanding after this offering.
 
    At September 30, 2000, there were options outstanding to purchase a total of
1,310,654 shares of common stock at a weighted average exercise price of $0.71
per share and 303,729 shares were reserved for grant of future options under our
1997 stock option plan. In November 2000, the board of directors approved an
increase in the number of shares available for issuance under our 1997 stock
option plan by 700,000. In December 2000, our board of directors adopted our
2000 employee stock purchase plan, our 2000 equity incentive plan and our 2000
nonemployee directors' stock option plan, under which an aggregate of 950,000
additional shares were reserved for issuance. At September 30, 2000, there were
warrants outstanding to purchase a total of 237,257 shares of common stock at an
exercise price of $12.00 per share. To the extent that any of these options or
warrants are exercised or any shares are issued under these plans, there will be
further dilution to new investors.
 
                                       21

<PAGE>
    Assuming the exercise in full of all options and warrants outstanding and
exercisable as of September 30, 2000, the average price per share paid by our
existing stockholders would be reduced by $    per share to $    per share.
After this offering, and assuming the exercise in full of all options and
warrants outstanding and exercisable as of September 30, 2000, the pro forma net
tangible book value as adjusted would be $    per share, representing an
immediate increase in net tangible book value of $    per share to existing
stockholders and an immediate dilution in net tangible book value of $    per
share to new investors.
 
                                       22

<PAGE>

                      SELECTED CONSOLIDATED FINANCIAL DATA
                (IN THOUSANDS, EXCEPT SHARE AND PER SHARE DATA)
 
    The following data, insofar as it relates to each of the years 1995 through
1999, has been derived from annual financial statements, including the
consolidated balance sheet at December 31, 1998 and 1999 and the related
consolidated statements of operations and of cash flows for the three years
ended December 31, 1999 and related notes appearing elsewhere in this
prospectus. The data for the nine months ended September 30, 1999 and 2000 has
been derived from unaudited financial statements also appearing in this
prospectus and which, in the opinion of management, include all adjustments,
consisting of only normal recurring adjustments, necessary for a fair statement
of the results for the unaudited interim periods. You should read the following
selected financial data set forth below in conjunction with "Management's
Discussion and Analysis of Financial Condition and Results of Operations" and
our financial statements and related notes appearing elsewhere in this
prospectus.
 

<TABLE>
<CAPTION>
                                                                                                             NINE MONTHS
                                                                                                                ENDED
                                                                YEAR ENDED DECEMBER 31,                     SEPTEMBER 30,
                                                  ----------------------------------------------------   -------------------
                                                    1995       1996       1997       1998       1999       1999       2000
                                                  --------   --------   --------   --------   --------   --------   --------
                                                                                                             (UNAUDITED)
<S>                                               <C>        <C>        <C>        <C>        <C>        <C>        <C>
CONSOLIDATED STATEMENT OF OPERATIONS DATA:
Revenues
  Collaborative revenues--related party.........  $    --    $    --    $   273    $ 1,300    $ 2,238    $ 1,334    $ 2,649
  Other research revenues.......................      300        438        562        119         --         --        119
                                                  -------    -------    -------    -------    -------    -------    -------
    Total revenues..............................      300        438        835      1,419      2,238      1,334      2,768
                                                  -------    -------    -------    -------    -------    -------    -------
Operating expenses
  Research and development(1)...................      264        421      2,295      5,856      7,625      5,582      7,253
  General and administrative(2).................       85        206      1,771      2,487      2,458      1,996      3,989
                                                  -------    -------    -------    -------    -------    -------    -------
    Total operating expenses....................      349        627      4,066      8,343     10,083      7,578     11,242
                                                  -------    -------    -------    -------    -------    -------    -------
Loss from operations............................      (49)      (189)    (3,231)    (6,924)    (7,845)    (6,244)    (8,474)
Interest income.................................        1         --        283        689        751        576      1,013
Interest expense................................       (4)        (3)       (34)      (168)      (351)      (238)      (293)
                                                  -------    -------    -------    -------    -------    -------    -------
Net loss........................................  $   (52)   $  (192)   $(2,982)   $(6,403)   $(7,445)   $(5,906)   $(7,754)
                                                  =======    =======    =======    =======    =======    =======    =======
Net loss per share, basic and diluted...........  $ (0.03)   $ (0.13)   $ (1.74)   $ (3.12)   $ (3.57)   $ (2.83)   $ (3.63)
                                                  =======    =======    =======    =======    =======    =======    =======
Weighted average shares used in computing net
  loss per share, basic and diluted(3)..........    1,523      1,523      1,712      2,049      2,087      2,083      2,134
                                                  =======    =======    =======    =======    =======    =======    =======
Pro forma net loss per share, basic and
  diluted.......................................                                              $ (0.96)              $ (0.83)
                                                                                              =======               =======
Weighted average shares used in computing pro
  forma net loss per share, basic and
  diluted(3)....................................                                                7,780                 9,360
                                                                                              =======               =======
</TABLE>

 

<TABLE>
<CAPTION>
                                                                                                 SEPTEMBER 30, 2000
                                                           DECEMBER 31,                       -------------------------
                                       ----------------------------------------------------                PRO FORMA
                                         1995       1996       1997       1998       1999      ACTUAL    AS ADJUSTED(4)
                                       --------   --------   --------   --------   --------   --------   --------------
                                                                                                     (UNAUDITED)
<S>                                    <C>        <C>        <C>        <C>        <C>        <C>        <C>
CONSOLIDATED BALANCE SHEET DATA:
Cash, cash equivalents and investment
  securities.........................  $      8   $      5   $ 12,418   $ 17,577   $ 12,209   $ 29,484
Working capital (deficit)............       (90)      (329)    11,765     16,939     10,788     27,149
Total assets.........................       227        223     14,705     21,063     15,518     33,471
Long-term debt, less current
  portion............................        --         76      1,177      3,367      4,432      4,632
Convertible preferred stock..........        --         --     14,512     24,665     24,665     46,502
Total stockholders' equity
  (deficit)..........................       (52)      (244)    (1,989)    (8,414)   (15,437)   (20,630)
</TABLE>

 
------------------------------
 
(1) Includes stock-based compensation of $3, $100, $38 and $353 for the years
    ended December 31, 1998 and 1999 and for the nine months ended
    September 30, 1999 and 2000, respectively.
 
(2) Includes stock-based compensation of $49, $6, $5 and $1,856 for the years
    ended December 31, 1998 and 1999 and for the nine months ended
    September 30, 1999 and 2000, respectively.
 
(3) Please see Note 2 of the notes to our consolidated financial statements for
    an explanation of the determination of the number of shares used in
    computing per share data.
 
(4) The pro forma as adjusted information in the table reflects the conversion
    of all of our outstanding shares of convertible preferred stock into shares
    of common stock and reflects the sale of           shares of common stock
    offered by us at an assumed initial public offering price of $          per
    share, the midpoint of the range on the cover of this prospectus, after
    deducting estimated underwriting discounts and commissions and estimated
    offering expenses payable by us.
 
                                       23

<PAGE>

                      MANAGEMENT'S DISCUSSION AND ANALYSIS
                OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS
 
    THE FOLLOWING "MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION
AND RESULTS OF OPERATIONS" SHOULD BE READ IN CONJUNCTION WITH "SELECTED
CONSOLIDATED FINANCIAL DATA" AND OUR CONSOLIDATED FINANCIAL STATEMENTS AND
ACCOMPANYING NOTES. OUR DISCUSSION MAY CONTAIN FORWARD LOOKING STATEMENTS BASED
UPON CURRENT EXPECTATIONS THAT INVOLVE RISKS AND UNCERTAINTIES, SUCH AS
STATEMENTS OF OUR PLANS, OBJECTIVES AND INTENTIONS. OUR ACTUAL RESULTS MAY
DIFFER MATERIALLY FROM THOSE INDICATED IN ANY FORWARD LOOKING STATEMENTS. SEE
"NOTE REGARDING FORWARD LOOKING STATEMENTS." FACTORS THAT COULD CAUSE OR
CONTRIBUTE TO THESE DIFFERENCES INCLUDE BUT ARE NOT LIMITED TO THOSE DISCUSSED
IN "RISK FACTORS" AND ELSEWHERE IN THIS PROSPECTUS.
 
OVERVIEW
 
    We were incorporated in 1993 and have devoted substantially all of our
resources since that time to the development of an integrated technology
platform and the discovery of novel small molecule drug candidates. We have not
been profitable and we have incurred substantial operating losses since
inception due in large part to expenditures related to our research and
development activities. At September 30, 2000, we have incurred an accumulated
deficit of $24.6 million. We expect to incur substantial increases in our
expenditures and operating losses for at least the next several years and until
we generate sufficient revenue to offset expenses. Research and development
costs will continue to increase as we seek to discover and develop a sustainable
pipeline of drug candidates and expand and maintain our integrated technology
platform. Our results of operations have fluctuated significantly from period to
period in the past and are likely to do so in the future. Due to the possibility
of fluctuations in our revenue and expenses, we believe that the period to
period comparisons of our operating results are not a good indication of our
future performance.
 
    Our income to date has been generated substantially from research and
milestone payments from our collaborative agreements, interest income and
governmental grants. A major component of our business strategy is to enter into
collaborations with pharmaceutical and biotechnology companies in order to
leverage the research, development, and commercial resources of our
collaborators to establish a pipeline of drug discovery programs and to
commercialize our drug candidates. Currently, our revenues are derived primarily
from two collaborative agreements with Allergan. These collaborations provide
for research funding through July 2001 and September 2002, respectively, and are
subject to rights of early termination. We expect our sources of revenues for
the next several years to consist of payments under our current and future
collaborations. We expect that our collaboration agreements typically will
provide for the following potential sources of revenues:
 
    - upfront payments upon entering into the agreements;
 
    - research funding throughout the term of the agreements;
 
    - milestone payments contingent upon achievement of agreed upon objectives;
      and
 
    - royalties upon the commercialization of products.
 
Revenues under collaborative agreements are recognized as research activities
are performed over the term of the agreements. Upfront license and milestone
payments that are related to future performance under such agreements are
deferred and recognized as revenue when earned over the term of the agreement.
 
    Our research and development expenses consist primarily of salaries and
other personnel-related expenses, facility costs and costs for equipment and
laboratory supplies. Our general and administrative expenses consist primarily
of personnel-related expenses for finance, business development and general
management, as well as professional fees, such as expenses for legal and
accounting services.
 
                                       24

<PAGE>
    Our discovery programs are at an early stage of development and we are
dependent on securing additional funding from both current and new
collaborations to meet our future funding requirements. Another component of our
business strategy is to manage our financial resources and level of investment
in drug discovery programs to balance our proprietary efforts and activities
under collaborations. As part of this strategy, we are planning to make
significant investments in our own research and development programs, which will
require us to obtain additional financial resources. In particular, we intend to
develop some of our own drug candidates through the early stages of clinical
development prior to entering into licensing and development agreements with
collaborators in return for a greater share of the revenues derived from the
resulting products. This strategy will require us to obtain additional financial
resources and invest more fully in our own programs. If adequate funds are not
available or are not available on acceptable terms, our ability to further
develop our drug candidates and fund our operations could be significantly
limited.
 
RESULTS OF OPERATIONS
 
    NINE MONTHS ENDED SEPTEMBER 30, 2000 AND 1999
 
    Revenues increased to $2.8 million for the nine months ended September 30,
2000 from $1.3 million for the nine months ended September 30, 1999. This
increase is primarily due to increased revenues recognized under our second
collaboration agreement with Allergan, which commenced in July 1999 and, to a
lesser degree, funding from a governmental grant. Our two collaboration
agreements with Allergan accounted for substantially all of our revenues during
these periods.
 
    Research and development expenses increased to $7.3 million for the nine
months ended September 30, 2000 from $5.6 million for the nine months ended
September 30, 1999, including stock-based compensation expense of $353,000 and
$38,000, respectively. This increase, other than stock-based compensation
expenses, is primarily due to costs associated with the expansion of our
research and discovery organization and our discovery programs. The increased
costs are largely comprised of personnel-related expenses, and expenditures for
laboratory supplies and equipment. We anticipate substantial increases in
research and development expenses in future periods related to further expansion
of our research and discovery organization and increased preclinical and
clinical expenses associated with our drug candidates.
 
    General and administrative expenses totaled $4.0 million for the nine months
ended September 30, 2000 compared to $2.0 million for the nine months ended
September 30, 1999, including stock-based compensation expense of $1.9 million
and $5,000, respectively. These expenses, other than stock-based compensation
expenses, were relatively consistent from period to period. We anticipate
increases in general and administrative expenses in future periods as we expand
our administrative organization to support the continued growth of our research
organization, and incur additional costs associated with operating as a public
company and increased business development activities.
 
    Stock-based compensation expense totaled $2.2 million for the nine months
ended September 30, 2000 compared to $43,000 for the nine months ended
September 30, 1999. This increase results from the amortization of deferred
stock compensation, compensation expense resulting from the modification of the
terms of an option grant, and compensation expense from the valuation of options
granted to consultants. During the nine months ended September 30, 2000, we
recorded deferred stock-based compensation totaling $1.2 million in connection
with the grant of stock options to employees. This amount has been reflected as
a component of stockholders' equity (deficit) and will be amortized to
operations over the vesting period of the options, generally four years. The
remaining unearned stock-based compensation of $1.3 million at September 30,
2000 will be recognized as expense in future years as follows: $191,900
remaining in 2000, $582,700 in 2001, $305,000 in 2002, $143,200 in 2003 and
$37,000 in 2004.
 
                                       25

<PAGE>
    We anticipate that additional deferred stock-based compensation will be
recorded for options granted after September 30, 2000, including approximately
$1.3 million for options granted from October 1, 2000 through November 30, 2000.
 
    Net interest income increased to $720,000 for the nine months ended
September 30, 2000 from $338,000 for the nine months ended September 30, 1999.
This increase is primarily attributable to increased interest income resulting
from higher levels of cash and investment securities in 2000. Increased interest
income during the nine months ended September 30, 2000 was offset in part by
additional interest expense associated with our loans.
 
    YEARS ENDED DECEMBER 31, 1999, 1998 AND 1997
 
    Revenues increased to $2.2 million for the year ended December 31, 1999 from
$1.4 million in 1998 and $835,000 in 1997. The increase in revenues during 1999
relative to 1998 is primarily due to an increase in revenues recognized under
our second collaboration agreement with Allergan, which commenced in July 1999.
The increase in revenues in 1998 relative to 1997 is primarily due to increased
revenues recognized under our first collaboration agreement with Allergan, which
began in September 1997. Other research revenues during 1997 were derived from
research funding from other agreements and a governmental grant. Other research
revenues during 1998 were derived from research funding from a government grant.
 
    Research and development expenses increased to $7.6 million for the year
ended December 31, 1999 from $5.9 million in 1998 and $2.3 million in 1997,
including stock-based compensation expense of $100,000, $3,000 and $0,
respectively. This increase, other than stock-based compensation expenses, is
primarily due to increased costs associated with expansion of our research and
discovery organization and our discovery programs, including increased
personnel-related expenses, and expenditures for laboratory supplies, expanded
facilities and equipment.
 
    General and administrative expenses totaled $2.5 million for the years ended
December 31, 1999 and 1998 and $1.8 million in 1997, including stock-based
compensation expense of $6,000, $49,000 and $0, respectively. This increase,
other than stock-based compensation expenses, reflects the expansion of our
administrative organization to support increased research and development
efforts, and expanded business development activities.
 
    Stock-based compensation expense totaled $106,000 for the year ended
December 31, 1999 compared to $52,000 for the year ended December 31, 1998. This
increase results from the amortization of deferred stock-based compensation and
compensation expense from the valuation of options granted to consultants.
During the year ended December 31, 1999, we recorded deferred stock-based
compensation totaling $470,000 in connection with the grant of stock options to
employees. This amount has been reflected as a component of stockholders' equity
(deficit) and will be amortized to operations over the vesting period of the
options, generally four years.
 
    Net interest income totaled $400,000 for the year ended December 31, 1999
compared to $521,000 for 1998 and $249,000 in 1997. The decrease in net interest
income during 1999 relative to 1998 is primarily attributable to increased
interest expense associated with our equipment and other loans. The increase in
net interest income in 1998 relative to 1997 is primarily due to increased
interest income resulting from higher levels of cash and investment securities
in 1998. Increased interest income during the year ended December 31, 1998 was
offset in part by additional interest expense associated with our loans.
 
LIQUIDITY AND CAPITAL RESOURCES
 
    Since inception, we have funded our operations primarily through private
placements of our preferred stock, payments under our collaborative agreements,
debt financing and interest income. At
 
                                       26

<PAGE>
September 30, 2000, we have received $47.9 million in net proceeds from the
sales of equity securities, including $6.0 million from one of our
collaborators, $7.8 million in payments from collaborative agreements,
$7.2 million in debt financing and $2.7 million in interest income.
 
    At September 30, 2000, we had approximately $29.5 million in cash, cash
equivalents and investment securities compared to $12.2 million at December 31,
1999. This increase in cash balances is largely attributable to net proceeds of
$21.8 million from the issuance of Series E preferred stock during the second
quarter of 2000, offset by $4.5 million in cash used in operating activities for
the nine months ended September 30, 2000. We have invested a substantial portion
of our available cash funds in investment securities consisting of high quality
debt instruments of financial institutions and corporations and U.S. Government
securities.
 
    At September 30, 2000, we have purchased $5.4 million in property and
equipment and we expect to acquire approximately $1.0 million in additional
property and equipment during the remainder of 2000. Since inception, we have
financed approximately $1.6 million of our property and equipment acquisitions
through equipment financing agreements.
 
    Net cash provided by financing activities totaled $23.1 million for the nine
months ended September 30, 2000 compared to $1.0 million for the nine months
ended September 30, 1999. This increase is primarily due to net proceeds of
$21.8 million from the issuance of Series E preferred stock and increased
proceeds from the issuance of debt, net of repayments during 2000. At
September 30, 2000, we had $4.7 million outstanding under a loan agreement with
The Vaekstfonden (The Danish Fund for Industrial Growth). This loan is funded on
a quarterly basis over the term of a research project up to a maximum commitment
of approximately 45 million Danish kroner, or approximately $5.3 million. The
loan accrues interest at 7.7% per annum and principal and interest are payable
in quarterly installments based on estimated project related revenues over an
anticipated period of five years. Should actual revenues fail to materialize or
fall short of projections, the loan may be forgiven or the repayment terms
revised at the discretion of The Vaekstfondon.
 
    At September 30, 2000, we had $1.2 million in outstanding borrowings under
two equipment financing agreements which are secured by the related equipment.
Outstanding balances under these agreements bear interest in the range of 10.6%
to 12.6% per annum and are due in monthly installments over a three to four year
period. At September 30, 2000, we had $1.7 million available under equipment
financing agreements, subject to compliance with specified financial covenants
and conditions. We also have commitments under operating leases for our
facilities and certain equipment requiring future payments totaling
$4.8 million through 2005.
 
    We believe our existing cash resources plus the proceeds of this offering
and anticipated proceeds from existing corporate collaborations will be
sufficient to fund our anticipated cash requirements through 2002. Our future
capital requirements will depend on many factors including:
 
    - progress in, and the costs of, our research and development programs;
 
    - the scope, prioritization and number of programs;
 
    - the progress of preclinical and clinical testing;
 
    - our ability to enter into additional collaborations;
 
    - the modification or termination of any of our current or future
      collaborations;
 
    - the time and costs involved in obtaining regulatory approvals; and
 
    - the costs involved in obtaining, enforcing and defending patent and other
      intellectual property rights.
 
                                       27

<PAGE>
We will need to raise substantial additional capital to fund our operations in
future periods. We intend to seek additional funding through collaborative and
licensing agreements, public or private equity or debt financing, or other
financing sources that may be available. We cannot assure you that additional
financing or collaborative and licensing agreements will be available when
needed or that, if available, this financing will be obtained on terms favorable
to us or our stockholders. If additional funds are raised through the sale of
equity securities, substantial dilution to existing stockholders may result. If
adequate funds are not available, we may be required to delay, or reduce the
scope of, or eliminate some or all of our research and development programs or
to relinquish rights to drug candidates at an earlier stage of development or on
less favorable terms than we would otherwise choose to do. Our failure to obtain
capital when needed could have a material adverse effect on our business,
financial condition and results of operations.
 
RECENTLY ISSUED ACCOUNTING STANDARDS
 
    In December 1999, the Securities and Exchange Commission issued Staff
Accounting Bulletin No. 101, or SAB 101, REVENUE RECOGNITION IN FINANCIAL
STATEMENTS. The objective of SAB 101 is to provide further guidance on revenue
recognition issues in the absence of authoritative literature addressing a
specific arrangement or a specific industry. We have adopted SAB 101 for all
periods presented.
 
    We expect to adopt Statement of Financial Accounting Standards No. 133, or
SFAS 133, ACCOUNTING FOR DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES,
effective January 1, 2001. SFAS 133 will require us to recognize all derivatives
on the balance sheet at fair value. We do not anticipate that the adoption of
SFAS 133 will have a significant effect on our results of operations or
financial position.
 
    In March 2000, the Financial Accounting Standards Board issued
Interpretation No. 44, or FIN 44, ACCOUNTING FOR CERTAIN TRANSACTION INVOLVING
STOCK COMPENSATION. We adopted FIN 44 effective July 1, 2000 with respect to
specific provisions applicable to new awards, exchanges of awards in a business
combination, modifications to outstanding awards, and changes in grantee status
that occur on or after that date. FIN 44 addresses practice issues related to
the application of Accounting Practice Bulletin Opinion No. 25, ACCOUNTING FOR
STOCK ISSUED TO EMPLOYEES.
 
QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK
 
    INTEREST RATE RISK
 
    We invest our excess cash in investment grade, interest bearing securities.
The primary objective of our investment activities is to preserve principal
while at the same time maximizing yields without significantly increasing risk.
To achieve this objective, we invest in highly liquid and high quality debt
instruments of financial institutions and corporations and U.S. government
securities with maturities of less than two years. If a 10% change in interest
rates were to have occurred on September 30, 2000, this change would not have
had a material effect on the fair value of our investment portfolio as of that
date.
 
    FOREIGN CURRENCY RISK
 
    We have a wholly owned subsidiary in Denmark, ACADIA Pharmaceuticals A/S,
which exposes us to foreign exchange risk. The functional currency of our
subsidiary is the Danish local currency. Accordingly, all assets and liabilities
of our subsidiary are translated at the current exchange rate at the balance
sheet date. Revenue and expense components are translated at weighted average
exchange rates in effect during the period. Gains and losses resulting from
foreign currency translation are included as a component of our stockholders'
equity (deficit). Other foreign currency transaction gains and losses are
included in our results of operations and, to-date, have not been significant.
We have not hedged exposures denominated in foreign currencies or any other
derivative financial instrument.
 
                                       28

<PAGE>

 
                                   BUSINESS
 
OVERVIEW
 
    We are a genomics-based drug discovery and development company that
efficiently identifies target-specific small molecule drug candidates using our
integrated technology platform. Our proprietary approach integrates genomics,
chemistry and biology to rapidly identify and validate drug targets and discover
chemistries specific to those targets. We have successfully applied our approach
to generate a drug discovery pipeline that currently includes six advanced
programs as well as a number of earlier stage research projects. We have rapidly
advanced two of these programs to development with a collaborator. The first
drug candidate, for glaucoma treatment, is undergoing a Phase I/IIa clinical
trial. The second drug candidate has been nominated for development as a novel
treatment for chronic pain. We also have four additional drug candidates in
late-stage preclinical testing. We focus on major diseases that represent some
of the largest pharmaceutical markets in the world, including schizophrenia,
Alzheimer's disease, chronic pain and glaucoma.
 
BACKGROUND ON DRUG DISCOVERY
 
    The drug discovery process is complex and involves multiple steps.
Currently, many drugs are discovered through screening large numbers of chemical
structures, or compounds, for a chosen disease target. Drugs are natural or
synthetic compounds that interact with a target molecule, normally a protein,
either to induce or to inhibit that molecule's function within the human body.
The key steps in the discovery of a compound for further development as a drug
candidate typically include:
 
    - identification of a suitable drug target, or target validation;
 
    - discovery of a lead compound;
 
    - optimizing the properties of the lead compound; and
 
    - preclinical testing and development of the lead compound.
 
    Recent advances in genomics research have led to the identification of a
large number of genes, which represent potential targets for therapeutic
intervention. As with genomic initiatives, researchers have made major advances
in chemistry techniques useful in the drug discovery process, including
combinatorial chemistry. As a result many pharmaceutical and biotechnology
companies now have access to large collections of diverse chemical structures,
referred to as libraries, which may include synthetic compounds and natural
product extracts. Researchers have also made major advances in the technologies
available for screening libraries to identify compounds that interact with a
given drug target.
 
CURRENT LIMITATIONS OF DRUG DISCOVERY AND GENOMICS
 
    Recent advances in genomics have the potential to significantly improve the
drug discovery process. As genomics efforts continue to identify new genes,
however, researchers face a major challenge in understanding the functional and
clinical relevance of this increasing wealth of genetic information. These
developments have not enabled the rapid identification of ideal drug targets,
because the gene sequence data by itself provides only limited information, if
any, about a gene's relationship to a specific disease. The following
limitations exist in the current process of moving from a gene to a drug:
 
    - Slow and cumbersome process--Identification of gene function is
      inefficient and time consuming.
 
    - Poor target selection--The inability to look broadly and functionally at
      targets often leads to the selection of inappropriate drug targets.
 
                                       29

<PAGE>
    - Nonselective drugs--Difficulties exist in finding highly selective
      chemistries for the appropriate target; therefore many resulting drugs are
      nonspecific in their action.
 
    The selection of targets for drug discovery and the identification of
specific lead chemistries have historically been inefficient processes. Even
after advances in genomics and chemistry, these two aspects of drug discovery
continue to represent critical bottlenecks that significantly limit the
efficiency and productivity of current discovery efforts. Inappropriate drug
targets combined with nonselective chemistries often lead to low success rates
and drugs with suboptimal clinical profiles, including poor efficacy and side
effects.
 
OUR SOLUTION
 
    We have developed a drug discovery approach based on our integrated
technology platform that combines genomics, chemistry and biology to both
validate drug targets and discover novel chemistries specific to those targets.
Our technology platform efficiently and productively links diverse genomic and
chemical information. This platform may be used to identify and validate
individual gene products as novel disease targeting mechanisms. Our technology
platform may also be used to discover novel small molecule drug candidates that
selectively target these individual gene products.
 
    We have established drug discovery and technical expertise in the areas of
genomics, functional genomics, molecular biology, ultra high throughput
screening, molecular and behavioral pharmacology, and combinatorial, medicinal
and analytical chemistry. We have assembled a large and diverse compound library
and have developed more than 250 functional assays for key genomic targets. We
have discovered novel specific chemistries in over 200 structural classes for 35
genomic targets. We also apply our technology to study the genetic variation on
genomic targets in patient populations. In addition to our internal
capabilities, we collaborate with world renowned scientists, clinicians and
academic institutions. We believe that our discovery expertise combined with our
technology platform creates a highly efficient and productive drug discovery
process that allows us to discover superior drug candidates more efficiently
than traditional approaches. We believe that our technology platform provides
the following benefits:
 
    - Productive and efficient drug discovery--Since 1997, we have generated six
      advanced drug discovery programs, two of which are now in development.
 
    - Effective target validation--We are able to identify the therapeutic
      relevance of genomic targets by using our proprietary assay technology,
      R-SAT, to functionally link genomic and chemical information. Targets for
      all six of our programs have been validated using our approach.
 
    - Target-specific drugs--Using our compound library and our proprietary
      combinatorial chemistries, we can identify specific chemistries for our
      validated targets, and thereby achieve therapeutic benefits without side
      effects.
 
    - Broad applicability--We apply our technology platform over a wide range of
      potential drug targets to address several therapeutic areas. Our efforts
      address many diverse classes of potential targets, including GPCRs,
      cytokine receptors, growth factor receptors, nuclear receptors, enzymes
      and neurotransmitter transporters.
 
                                       30

<PAGE>
OUR DRUG DISCOVERY APPROACH
 
    KEY COMPONENTS OF OUR PLATFORM TECHNOLOGY
 
    Our drug discovery approach is based on our integrated technology platform
and validates novel genomic targets while simultaneously identifying specific
chemistries for those targets. This proprietary platform consists of four key
elements:
 
    - R-SAT FUNCTIONAL ASSAY PLATFORM. Our proprietary Receptor Selection and
      Amplification Technology, which we refer to as R-SAT, is the foundation of
      our integrated technology platform. R-SAT is a functional cell-based
      chemical compound testing system that we have broadly applied to measure
      the ability of compounds to alter cellular function. Our studies have
      shown that the results are predictive of the clinical activities of drugs.
      This technology is scaleable and we have integrated it into an industrial
      process for the analysis of diverse compound libraries.
 
    - GENOMIC TARGETS. We have developed what we believe is one of the most
      comprehensive sets of functional genomic assays, encompassing more than
      250 genomic targets. We have prioritized the discovery and testing of
      genomic targets to those targets that we believe are most likely to
      interact with small organic molecules.
 
    - DIVERSE COMPOUND LIBRARY. We have a large and diverse compound library,
      which we use as a resource to search for novel structure-activity
      relationships, which are the relationships between chemical structure and
      pharmacological activity. This library consists of over 700,000 small
      organic compounds that have been characterized and quality controlled for
      purity and drug-like characteristics.
 
    - REFERENCE DRUGS. We have assembled a collection of over 1,000 compounds,
      primarily consisting of currently and formerly marketed drugs, and drugs
      that failed in clinical trials, each with known effects or side effects on
      the central nervous system. Our reference drugs, when combined with R-SAT
      and the genomic targets, provide an important resource to link clinical
      and physiological effects of drugs with genomic targets.
 
                                     CHART
 
    [Depiction of ACADIA's Technology: Three boxes with a single circle overlaid
on each are vertically stacked to the left of a large triangle that points to
two boxes on the right. The top box of the three is captioned "Diverse Compound
Library" and its overlaid circle depicts chemical structures. The middle box is
captioned "Genomic Targets" and its overlaid circle depicts a strand of DNA. The
bottom circle is captioned "Reference Drugs" and its overlaid circle depicts a
chemical structure. The triangle is captioned "R-SAT." The top of the two boxes
is captioned "Validated Targets" and the bottom box is captioned
"Target-Specific Chemistries." Beneath and spanning the length of these figures
is a bracket pointing down to the text "Technology Platform."]
 
                                       31

<PAGE>
    HOW WE USE OUR TECHNOLOGY
 
    To validate novel targets and find target-specific chemistries, our
discovery approach can be applied in either of two complementary ways: an
evidence-based approach or a chemistry-based approach. With the evidence-based
approach, we match the effects of reference drugs on genomic targets using R-SAT
to better understand the clinical relevance of a genomic target. Our
evidence-based approach relies on the fact that most currently marketed drugs
are not completely target-specific and interact with a variety of gene products
to cause side effects. A thorough understanding of an established drug's
multiple target interactions coupled with knowledge about the clinical
experience related to its use in patients allows us to reach conclusions
regarding the mechanism of action underlying its clinical efficacy, as well as
the targets responsible for side effects. This allows us to differentiate
between the therapeutic targets and those targets that are associated with side
effects.
 
    Our second approach, the chemistry-based approach, uses high throughput
screening of compound libraries with detailed pharmacologic profiling of the
active chemistries using R-SAT. This process enables us to discover novel
proprietary chemistries that selectively target individual gene products and use
these as critical tools to determine the therapeutic potential of these targets.
We believe that our discovery expertise combined with our integrated technology
platform creates a highly efficient and productive drug discovery process that
allows us to discover superior drug candidates more efficiently than traditional
approaches.
 
OUR PROGRAMS
 
    We have used our integrated technology platform to generate a drug discovery
pipeline that currently includes six advanced programs. Our programs address
major diseases that are not well served by currently available therapies and
that represent significant commercial markets. We believe that these disease
areas are well suited to genomic approaches and that our drug candidates provide
the potential for improved therapeutic profiles relative to existing therapies.
The following table summarizes key information for our gene product specific
drug candidates.
 

<TABLE>
<CAPTION>
                                                                                               COMMERCIAL
PROGRAM                           STATUS                  OUR KEY ACHIEVEMENTS                   RIGHTS
-------                       ---------------  -------------------------------------------   --------------
<S>                           <C>              <C>                                           <C>
GLAUCOMA
  adrenergic agonist          Phase I/IIa      Identified and validated a specific             Allergan(A)
  (AGN 195795)                Clinical Trial   adrenergic target that affects intraocular
                                               pressure.
                                               Discovered a specific drug candidate that
                                               demonstrates a superior therapeutic profile
                                               in animal models relative to current
                                               adrenergic therapies.
  muscarinic agonist          Preclinical      Identified and validated a specific             Allergan(B)
                                               muscarinic target that affects intraocular
                                               pressure.
                                               Discovered a specific drug candidate that
                                               demonstrates a superior therapeutic profile
                                               in animal models relative to current
                                               muscarinic therapies.
CHRONIC PAIN
  GPCR agonist                Development      Identified and validated a specific GPCR as     Allergan(A)
  (AGN 197075)                Candidate        a target for the treatment of chronic pain.
                                               Discovered a drug candidate that was shown
                                               to be highly efficacious when administered
                                               orally in animal models, and does not
                                               exhibit the side effects common to pain
                                               drugs.
</TABLE>

 
                                       32

<PAGE>
 

<TABLE>
<CAPTION>
                                                                                               COMMERCIAL
PROGRAM                           STATUS                  OUR KEY ACHIEVEMENTS                   RIGHTS
-------                       ---------------  -------------------------------------------   --------------
<S>                           <C>              <C>                                           <C>
SCHIZOPHRENIA
  m1 muscarinic agonist/      Preclinical      Discovered specific drug candidates with a        ACADIA
  dopamine D(2) antagonist                     dual mechanism of action that demonstrate
                                               activity when administered orally in animal
                                               models of psychosis.
  5-HT(2A) inverse agonist    Preclinical      Identified and validated 5-HT(2A) inverse         ACADIA
                                               agonism as a therapeutic targeting
                                               mechanism for antipsychotic drugs.
                                               Discovered specific drug candidates with
                                               activity in animal models of psychosis.
ALZHEIMER'S DISEASE
  m1 muscarinic agonist       Preclinical      Discovered specific drug candidates with          ACADIA
                                               activity in animal models of psychotic
                                               symptoms associated with Alzheimer's
                                               disease.
</TABLE>

 
--------------------------
 
    "Phase I/IIa Clinical Trial" means that our collaborator is conducting a
    clinical trial designed to provide information on safety and preliminary
    efficacy in groups of patients.
 
    "Development Candidate" means that our collaborator has nominated a drug
    candidate for development and is performing toxicology, manufacturing and/or
    other studies designed to compile data necessary for submission of an IND
    application to the FDA.
 
    "Preclinical" means that drug candidates have been discovered and evaluated
    in relevant animal models; these drug candidates meet specified preclinical
    criteria and are undergoing further preclinical testing designed to enable
    the selection of a Development Candidate for clinical testing.
 
    "Allergan(A)" indicates that the commercialization of this program is
    governed by the terms of our September 1997 Collaboration Agreement with
    Allergan, Inc. discussed under "--Collaboration Agreements."
 
    "Allergan(B)" indicates that the commercialization of this program is
    governed by the terms of our July 1999 License and Collaboration Agreement
    with Allergan, Inc. described under "--Collaboration Agreements."
 
GLAUCOMA
 
    Glaucoma is an eye disease that is associated with the degeneration of the
optic nerve. An important factor related to glaucoma is increased fluid pressure
within the eye, or intraocular pressure. Initially, glaucoma causes blind spots
in the visual field and, if left untreated, can result in blindness. In fact,
glaucoma is the second leading cause of blindness. According to the Glaucoma
Research Foundation, an estimated 3 million people in the United States and
67 million people worldwide have glaucoma. In 1999, global sales for glaucoma
therapeutics totaled $1.8 billion. It is expected that global sales of glaucoma
therapeutics will increase significantly as awareness and diagnoses increase and
the general population ages. Currently, physicians treat glaucoma with multiple
classes of therapeutics to optimize therapy and minimize side effects.
Therefore, we believe significant market demand exists for a novel glaucoma
therapeutic that offers superior efficacy with minimal side effects.
 
    We have two programs in glaucoma and have formed two collaborations with
Allergan, Inc. to develop and commercialize drug candidates from these programs.
These drug candidates address different but complementary therapeutic mechanisms
and we believe that they provide potential advantages as compared to current
therapies.
 
    SPECIFIC ADRENERGIC AGONIST:  Adrenergic agonists reduce intraocular
pressure and may have neuroprotective effects on the optic nerve. In
collaboration with Allergan, we have identified and validated a specific
adrenergic gene product that affects the lowering of intraocular pressure and
have discovered a development candidate, AGN 195795, that selectively activates
this gene product. In a pivotal primate model of glaucoma, our drug candidate
demonstrated effects indicative of clinical
 
                                       33

<PAGE>
efficacy. In addition, studies in other animal models suggest absence of
activities indicative of side effects commonly produced by nonselective
adrenergic drugs such as sedation and cardiovascular side effects. AGN 195795
has a preclinical profile that is superior to that of currently used adrenergic
drugs, suggesting that it may offer potential advantages to patients. A Phase
I/IIa placebo controlled, multicenter clinical trial using different dosing
regimens has begun at major medical centers in the United States. We anticipate
that the analysis from the Phase I/IIa clinical trial will be completed in the
second half of 2001.
 
    GENE PRODUCT SPECIFIC MUSCARINIC AGONIST:  Specific muscarinic agonists are
designed to treat glaucoma by increasing the outflow of ocular fluid, thereby
reducing the intraocular pressure. We have identified a specific muscarinic gene
product that affects the lowering of intraocular pressure and have discovered
lead compounds that selectively activate this gene product. In a pivotal primate
model of glaucoma, our drug candidates demonstrate efficacy and a long duration
of action, without visual disturbances including pupil contraction. Pupil
contraction, which can cause night blindness and other side effects, is believed
to be linked to the nonselective action of the drug pilocarpine on muscarinic
receptors. The long duration of action and the favorable preclinical side effect
profile of our target-specific muscarinic agonist indicates therapeutic benefits
as compared to the nonselective drug pilocarpine. Several drug candidates are
undergoing further testing in pivotal animal models designed to allow Allergan
to select a development candidate and gather data necessary for submission of an
IND application to the FDA.
 
CHRONIC PAIN
 
    Pain can be classified in terms of its duration as either acute or chronic.
Chronic pain typically results from a chronic illness or appears spontaneously
and persists for undefined reasons. Examples of chronic pain include chronic
lower back pain, neuropathic pain and pain resulting from bone cancer or
advanced arthritis. Neuropathic pain, a specific type of pain caused by injury
to the nerves that sense pain, is a common and growing subset of pain. Common
causes include diabetes, HIV and nerve damage. Patients with chronic pain
commonly suffer from both the state of physical pain as well as a general
decline in the quality of life.
 
    The worldwide market for pain drugs totaled over $16 billion in 1997. In the
United States and Western Europe the corresponding market for pain drugs totaled
nearly $12 billion. The U.S. market for prescription pain drugs has grown by
approximately 15% per year during the past five years due to a number of
factors.
 
    The traditional method of treating chronic pain is through opioid
painkillers. Although there has been little innovation in the area of opioid
painkillers, sales in the United States were approximately $2.5 billion in 1999.
Despite widespread clinical use of opioids, such as morphine, pain management
remains less than optimal. Opioid painkillers have significant adverse side
effects that limit their usefulness, including respiratory depression, nausea,
vomiting, dizziness, sedation, mental clouding, constipation, urinary retention
and severe itching. In addition, chronic use of opioid painkillers can lead to
the need for increasing dosage, and potentially, addiction.
 
    The most common treatments for neuropathic pain are Neurontin, a seizure
medication, and antidepressants. Neurontin, in spite of being relatively
ineffective, had sales of approximately $900 million in 1999.
 
    SPECIFIC GPCR AGONIST:  In collaboration with Allergan, we have identified
and validated a specific GPCR as a target for chronic pain. We discovered a
novel lead chemistry by ultra high throughput screening of our diverse compound
library. Subsequent lead optimization resulted in the discovery of AGN 197075, a
small molecule drug that selectively activates this gene product. AGN 197075 was
shown to be highly efficacious when administered orally in relevant animal
models of pain, suggesting that it may offer potential as a new therapy for
chronic pain. In laboratory studies, AGN 197075 does not exhibit common side
effects of pain drugs, including sedation and cardiovascular, respiratory and
 
                                       34

<PAGE>
gastrointestinal effects. Allergan has nominated this drug candidate for
development and is conducting toxicology, manufacturing and/or other studies
designed to compile data necessary for submission of an IND application to the
FDA.
 
SCHIZOPHRENIA
 
    Schizophrenia is a common form of psychotic illness characterized by
disturbances in thinking, emotional reaction and behavior. It is one of the most
debilitating mental illnesses known and often requires patients to be under
medical care for their entire lives. According to the National Institutes of
Health, about 2.7 million people in the United States suffer from schizophrenia,
with approximately 300,000 new cases diagnosed each year. Worldwide sales of
antipsychotics totaled approximately $3.7 billion in 1999. Annual direct and
indirect healthcare costs for schizophrenia are approximately $45 billion in the
U.S. and over $100 billion worldwide. Traditional antipsychotic medications fail
to treat both cognitive and emotional symptoms and are often associated with
severe dose limiting side effects. While the more recently developed atypical
antipsychotic drugs exhibit fewer side effects, these drugs are far from
optimal. We believe that a significant market opportunity exists for new
therapeutics that have improved efficacy, reduced side effects and activity in
refractory patients.
 
    We have established two internal programs in schizophrenia, which provide us
with multiple drug targets that address different therapeutic mechanisms and
disease populations. We believe that our drug candidates provide potential
advantages compared to current therapies. We are also complementing these
programs through pharmacogenomic studies of schizophrenia patients.
 
    SPECIFIC M1 MUSCARINIC AGONIST/DOPAMINE D(2) ANTAGONISTS:  Our studies
suggest that m1 agonism and D(2) antagonism may be synergistic antipsychotic
mechanisms, and that m1 agonism has the potential to mitigate some of the
cognitive side effects of the typical antipsychotics that are currently
marketed. Drug candidates from this program are designed to target patients
responding to traditional antipsychotic agents. Our discovery efforts have
identified compounds that uniquely combine dopamine D(2) antagonism and m1
muscarinic agonism. Subsequent lead optimization resulted in the discovery of
gene product specific drug candidates that were selected for preclinical
testing. These drug candidates demonstrate IN VIVO activity in animal models of
schizophrenia, favorable pharmacokinetic properties and oral bioavailability. We
are conducting additional preclinical testing designed to select a drug
candidate for clinical development.
 
    SPECIFIC 5-HT(2A) INVERSE AGONISTS:  In contrast to currently marketed
antipsychotic drugs, selective 5-HT(2A) inverse agonists do not interact with
dopamine D(2) or other receptors believed to be responsible for side effects
such as motor disorders, emotional flattening and obesity. We believe these drug
candidates will target patients not responding, or responding unfavorably, to
traditional antipsychotic agents. Our discovery efforts have identified and
validated inverse agonism of the 5-HT(2A) receptor as a targeting mechanism that
is shared by most of the currently marketed antipsychotic drugs. We have also
discovered that these drugs have many other activities that may contribute to
their clinical profiles. For example, the typical antipsychotics also have
higher potency as dopamine D(2) receptor antagonists, while the newer atypical
antipsychotics are more potent as 5-HT(2A) inverse agonists. Employing ultra
high throughput screening, we identified novel, proprietary chemistries that are
potent and have selectivity as 5-HT(2A) inverse agonists. From these
chemistries, our discovery efforts have identified gene product specific drug
candidates that were selected for preclinical testing. These drug candidates are
potent in animal models of schizophrenia. Hence, we believe that our 5-HT(2A)
inverse agonists will exhibit clinical efficacy with fewer side effects than
current antipsychotics. Our drug candidates are undergoing preclinical testing
designed to select a drug candidate for clinical development.
 
    PHARMACOGENOMIC STUDIES OF ANTIPSYCHOTICS:  In collaboration with scientists
at the Karolinska Institute, we are studying the relationship between the
genomic targets and clinical outcomes in individual schizophrenia patients.
There are several different patient groups that suffer from schizophrenia. One
way to differentiate these patient groups is to classify them according to their
 
                                       35

<PAGE>
responsiveness to different types of drugs. Some schizophrenic patients respond
well to treatment with haloperidol and similar typical antipsychotics whereas
others do not respond to those drugs but do respond to treatment with atypical
drugs such as clozapine. We are focusing our initial studies on these two well
defined groups of patients. These studies are expected to provide insight into
the relative clinical roles of selected targets for different classes of
antipsychotic drugs, and how these genomic targets vary in patient populations.
Results from these studies will provide information that may be relevant to both
of our schizophrenia programs, and the selection of patients for future clinical
trials.
 
ALZHEIMER'S DISEASE
 
    Alzheimer's disease is the most common cause of dementia in older people. A
progressively debilitating disease, Alzheimer's disease is most common among
older people and its prevalence is increasing significantly as a function of the
aging population. An estimated 4 million people in the U.S. over the age of 65
suffer from Alzheimer's disease. Prevalence rates rise from 3% at age 65 to 47%
by age 85. By various mechanisms, Alzheimer's disease causes the death of nerve
cells within the brains of afflicted patients, resulting in impaired cognitive
function and significant changes in mood and behavior. Currently available drugs
to treat Alzheimer's disease attempt to substitute for the cholinergic deficit
in this disease by inhibiting the enzyme acetylcholinesterase. Because
acetylcholinesterase inhibitors indirectly activate all muscarinic receptors,
these treatments often lead to dose limiting cardiovascular and gastrointestinal
side effects, which may cause some patients to reduce or discontinue use of the
drugs. Even with these limitations, these drugs had sales of $600 million in
1999.
 
    One muscarinic receptor, the m1 receptor, is widely believed to be
associated with memory and cognition. This has led to the hypothesis that a
selective m1 receptor agonist could potentially treat Alzheimer's disease
without dose limiting side effects caused by nonselective muscarinic drugs. Due
to the ineffectiveness of current therapies, a large market opportunity exists
for new entrants with superior levels of efficacy.
 
    SPECIFIC M1 MUSCARINIC AGONIST:  We have discovered what we believe is the
first uniquely selective series of m1 receptor agonists using our integrated
technology platform. Following this discovery, we have engaged in an aggressive
chemistry effort, which has resulted in the synthesis of more than 500 analogs,
many with improved potency, efficacy and bioavailability in animal models. We
have selected gene product specific drug candidates for preclinical testing.
These drug candidates have shown behavioral effects in animal models of
psychotic symptoms associated with Alzheimer's disease, without evidence of
cardiovascular or gastrointestinal side effects, suggesting that they may offer
advantages relative to existing treatments. These drug candidates are undergoing
additional preclinical testing designed to select a drug candidate for clinical
development.
 
    PHARMACOGENOMIC STUDIES OF PATIENTS WITH ALZHEIMER'S DISEASE:  In
collaboration with scientists at Emory University, we are studying the
relationship between the genomic targets and clinical outcomes in individual
patients with Alzheimer's disease. Some of these patients respond well to
treatment with the acetylcholinesterase inhibitor, donepezil, whereas others do
not respond. Hence, the patients may be grouped according to donepezil
response/no response criteria. This study design may provide insights into the
interindividual genetic variation in target function and how this affects the
patient responses to donepezil. Results from these studies may provide
information relevant to our Alzheimer's disease program and for the selection of
patients in future clinical trials.
 
OUR RESEARCH PROJECTS
 
    Our integrated technology platform has produced a steady output of new
validated targets and related target-specific chemistries that serve as starting
points for novel research projects. In addition to our drug discovery programs,
which represent advanced efforts employing dedicated chemistry and pharmacology
groups and, when relevant, other preclinical capabilities, we also have earlier
stage research projects in several different areas. These research projects aim
to answer specific scientific
 
                                       36

<PAGE>
questions using limited personnel resources. When all key criteria have been
fulfilled, research projects may be elevated into new drug discovery programs.
Some of our more advanced current research projects focus on depression, feeding
and obesity, and other indications. We believe that these research projects will
continue to supply us with additional drug candidates in the future.
 
    In the area of depression, we have identified a GPCR that is targeted by
many marketed antidepressants using our evidence-based approach. Following
successful ultra high throughput screening of our diverse compound library, we
have available selective chemistries for this potential depression target and we
are currently studying the complete pharmacological profile of these
chemistries. Antidepressant drugs that interact with the optimal target(s) may
produce a quicker onset of action, a higher response rate and fewer side effects
than currently available therapies. We are also establishing appropriate
behavioral pharmacology models to enable critical animal proof of concept
studies.
 
    In the area of feeding and obesity, we have used our evidence-based approach
to identify likely GPCR targets. The targets have been used in ultra high
throughput screening of our diverse compound library to identify chemical
starting points for a potential program. In addition, most of the peptide
receptor targets that have been implicated in feeding and obesity have been
introduced in ultra high throughput screening of our diverse compound library,
searching for agonist chemistries. This has led to the identification of a
specifically acting small molecule peptide receptor agonist. Currently, we are
seeking to identify the most promising chemical starting point for a potential
program by careful pharmacological studies.
 
    In our functional genomics collaboration with Allergan, we have retained
development rights to inventions in the adrenergic program for applications in
the neuropsychiatric disease area. Through this collaboration, we have
identified a variety of unique gene product specific adrenergic leads, which
possess attractive pharmacokinetic properties, such as oral bioavailability. We
believe that these compounds provide us with the opportunity to explore
previously unrealized therapeutic opportunities for adrenergic therapies in the
neuropsychiatric area. In this program, we intend to evaluate our gene product
specific leads in animal models mimicking various neuropsychiatric conditions,
including anxiety/depression, schizophrenia, Alzheimer's disease and attention
deficit/hyperactivity disorder.
 
OUR STRATEGY
 
    Our goal is to discover and develop novel target-specific drugs that address
large unmet medical needs. There are six basic elements to our business and
scientific strategy:
 
    FOCUS ON DISEASES WITH LARGE UNMET MEDICAL NEEDS THAT ARE WELL SUITED TO
     GENOMIC APPROACHES.
 
    We use our technology and scientific expertise to understand the genetic
basis of drug action. Our internal programs address disorders for which existing
therapies interact nonspecifically with several gene targets, leading to side
effects. In these areas there is a need to discover small molecule drug
candidates that are highly selective for the desired gene target and therefore
will have significantly improved therapeutic profiles. We will continue to
target diseases that are not well served by currently available medications and
which represent some of the largest pharmaceutical markets in the world.
 
    BUILD A LARGE AND DIVERSIFIED PRODUCT PORTFOLIO.
 
    We intend to use our integrated technology platform to generate drug
candidates to treat a variety of diseases. We have diversified our drug
discovery efforts by pursuing a portfolio of discovery programs and multiple
targets and drug candidates both independently and with our collaborators. We
believe that the breadth of our programs will reduce the risks inherent in drug
discovery and increase the likelihood of commercial success. We intend to pursue
a broad range of programs to continue to generate a sustainable pipeline of drug
candidates.
 
                                       37

<PAGE>
    ADVANCE SELECTED DISCOVERY PROGRAMS INTERNALLY THROUGH EARLY CLINICAL
     DEVELOPMENT.
 
    We plan to advance some of our discovery programs through the early stages
of clinical development prior to entering collaboration agreements. We believe
the varied nature of our drug discovery programs will enable us to internally
develop some of our drug candidates to a later stage. For programs that require
large resource allocations, we will establish collaborations at an earlier stage
of development to leverage the resources and expertise of pharmaceutical
partners.
 
    COMMERCIALIZE DRUG CANDIDATES THROUGH LICENSING AND DEVELOPMENT
     COLLABORATIONS.
 
    We plan to develop and commercialize our drug candidates through additional
collaborations with pharmaceutical and biotechnology companies. We intend to
evaluate each project on an individual basis and form collaborations at the
development stage that we believe optimizes our position while balancing our
financial and technical risks.
 
    COMMERCIALIZE OUR INTEGRATED TECHNOLOGY PLATFORM THROUGH FUNCTIONAL GENOMICS
     COLLABORATIONS.
 
    We intend to leverage our integrated technology platform and scientific
expertise by forming functional genomics collaborations with pharmaceutical,
biotechnology and other companies. These collaborations will capitalize on our
strengths in the areas of target validation, lead discovery and
pharmacogenomics. We believe that our technology and expertise may be applied to
these and other potential commercial opportunities and provide a potential
source of revenues.
 
    EXPAND OUR TECHNOLOGY PLATFORM LEADERSHIP.
 
    We believe that our technology platform which combines genomics, chemistry
and biology is superior at identifying novel genomic targets together with their
specific chemistries. We will continue to improve the scientific excellence of
our integrated technology platform and may license or acquire technologies that
complement our core capabilities. We will continue to protect and build on our
existing patent portfolio, and also rely on trade secrets to protect our
proprietary technologies. In addition, we will continue to recruit highly
skilled scientists and collaborate with leading scientific and clinical advisors
in each of our program areas.
 
TECHNOLOGY OVERVIEW
 
    We have built an integrated technology platform that interfaces with our
drug discovery capabilities. We believe that our technology platform will
continue to efficiently convert genomic information into a flow of novel
validated targets and target-specific chemistries, thereby providing us with
excellent starting points for additional drug discovery programs. Key components
of our technology platform include:
 
    R-SAT FUNCTIONAL ASSAY SYSTEM.  Our proprietary Receptor Selection and
Amplification Technology, which we call R-SAT, is the foundation of our
integrated technology platform. R-SAT is a cell-based assay system that has been
broadly applied to measure the ability of drugs to affect the function of gene
products. This assay system may be used to measure the ability of a drug to
activate or inhibit a wide range of gene products and is useful in assessing the
functional relevance of potential drug targets and in predicting the clinical
activity of novel drugs.
 
    In our R-SAT assay, a series of potential target genes are mixed together
and transferred to cells in culture. In the absence of an added test compound,
the cells that take up the genes behave normally. The cells continue to grow
only until they encounter another cell, at which point all cellular growth
ceases. If a test compound activates the product of one of the genes, the cells
that express that gene are able to grow and all other cells in the culture do
not grow. The cells with the compound's target are selected and amplified in the
culture relative to cells that make the other target genes. In short, the
technology uses the principle of genetic selection as a method to evaluate
compound/target interactions.
 
                                       38

<PAGE>
    Target genes are mixed with marker genes that change color intensity. The
number of marker gene molecules increases as the number of cells that express a
target for a given compound increase. As a result, when a compound activates a
target the intensity of color increases. In contrast to competing
"transcription-based marker gene" assays, our R-SAT technology does not rely on
changes in numbers of marker genes within a given cell.
 
                         R-SAT FUNCTIONAL ASSAY SYSTEM
 
                                     CHART
 
    [R-SAT FUNCTIONAL ASSAY SYSTEM: On the left is a line of cells Labeled "t1"
through "t6". Beneath these cells is a small hexagon and the text "+ Compound."
An arrow points down from here to the same line of cells, t1 through t6, except
that there are now many t4 cells replicated below the line of cells. One of
these t4 cells is magnified to the right of these graphics and is labeled
"Cell." The magnified cell shows the hexagonal compound attached to a cell
marked t4 which is linked by two downward arrows to a depiction of cell growth.
To the left of these arrows is a double arrow pointing towards the arrows and
captioned "Helper Gene." To the right of the magnified cell are three items of
text. "Activation of target 4 by compound" is linked by a downward arrow to
"Engineered signal" which is linked by a downward arrow to "Cell growth
enabled."]
 
------------------------
 
    This diagram depicts six distinct cells, each expressing a different target,
    targets 1 through 6, which are incubated with a compound. The compound is
    specific to one of the targets, target 4 in this case, which allows the cell
    containing the compatible target to grow.
 
    There are a number of features of our R-SAT system that we believe make it a
highly efficient and productive tool. First, we have shown that this technology
may be broadly applied to a wide range of gene products. Second, we have
demonstrated that there is a strong correlation between the functional
properties, or pharmacology, as determined by our R-SAT system and events in
humans. Third, the technology allows for a group of genes or whole gene families
to be tested simultaneously, which we refer to as a multiplex. This feature,
combined with the simplicity of our assay format and other factors, allows our
tests to be automated and performed at ultra high throughput.
 
    FUNCTIONAL GENOMIC ASSAYS.  We have developed what we believe is one of the
leading, most comprehensive sets of functional genomic assays for use in our
R-SAT system. We currently have more than 250 genomic targets in our assay
format, which we refer to as our genomic targets. This set of assays is being
expanded on an ongoing basis as new genomic targets are discovered. We
prioritize the genomic targets that we believe are most likely to interact with
small organic compounds.
 
    Researchers have classified genes into categories, or gene families, based
upon similar characteristics. A large number of genes are referred to as
receptors, many of which are located on the surface of cells. The largest
category of receptors is GPCRs. This gene family is the predominant category of
receptors involved in cellular function, and represents the most common targets
for many of the world's largest selling pharmaceutical products. We have
developed significant expertise in the area of GPCRs and have established this
important gene family as our highest priority targets for drug discovery. We
have isolated genes for approximately 200 GPCRs and have integrated more than
130 of these into our functional genomic assays. We have also developed assays
for members of other gene
 
                                       39

<PAGE>
families including cytokine receptors, growth factor receptors, nuclear
receptors, enzymes and neurotransmitter transporters.
 
    GENOMIC TARGET DISCOVERY.  The publicly available genomic databases are
rapidly being populated with sequence data from a variety of sources involved in
the human genome project. Our scientists search these databases for sequences
that are related to known targets of small organic compounds. These searches are
yielding large numbers of novel genes that are related in sequence to known
genes. Novel genes with no known ligands or function are referred to as orphans.
Our initial efforts in the orphan area have focused on genes related to GPCRs.
Our scientists have identified many novel orphan GPCRs. Several of these novel
genes are selectively expressed in the human brain. To date, we have integrated
more than 20 orphan GPCRs into our functional genomics assay format.
 
    ULTRA HIGH THROUGHPUT SCREENING.  We have established a state of the art
screening infrastructure and capability based on our R-SAT system. The
simplicity of our assay format, multiplexing capability, and miniaturization and
robotics, make our screening process highly efficient and productive in terms of
the numbers of compounds and breadth of genes that can be functionally tested.
Our screening infrastructure currently provides for a sustainable capacity of
approximately 250,000 functional tests per week and we have achieved a level of
over 500,000 functional tests per week. We believe that we can readily expand
this capacity. Our screens are normally multiplexed with four to six gene
products per test. As a result, our infrastructure provides for more than
1 million compound/gene interactions on a weekly basis.
 
    HIGH THROUGHPUT PHARMACOLOGY AND PROFILING.  Many of the competing high
throughput technologies either measure the simple binding of compounds to a
target or provide only qualitative approximations of function, thereby requiring
secondary assays to provide quantitative results. These secondary assays are
generally costly and time consuming, creating a bottleneck in the discovery
process. In contrast, our R-SAT assay system allows the quantitative and
physiologically predictive evaluation of compounds. The potency, efficacy and
selectivity of large numbers of compounds from screening can be established
rapidly using the same functional assay platform. As a result, our assay system
may relieve a major bottleneck that exists in many screening operations.
 
    One important feature of the R-SAT system, when used in high throughput
pharmacology, is its ability to accurately measure the full range of potential
activities of compounds at gene products. Many assay technologies are unable to
distinguish between partial agonists or full agonists, or between inverse
agonists and antagonists. In contrast, our R-SAT technology has the ability to
reliably and accurately measure the full range of activities.
 
    COMPOUND LIBRARIES.  Access to large, high quality libraries of diverse
molecular structures is an important aspect of our drug discovery efforts. We
have developed a large and diverse compound collection, referred to as our
diverse compound library, which we use as a resource to search for compounds
with functional activities. Our diverse compound library consists of
approximately 200,000 small organic compounds that have been characterized and
quality controlled for purity and drug like characteristics. We have collected
these compounds from a variety of sources throughout the world including
academic medicinal chemistry laboratories, pharmaceutical and biotechnology
companies, combinatorial chemistry companies, other commercial suppliers and our
own synthetic efforts. In addition, we have a collaboration with ArQule, Inc.,
and we have integrated more than 500,000 of ArQule's compounds into our
screening operation. Our internal combinatorial chemistry expertise provides our
library with another source of unique, diverse chemistry. We have developed a
convenient combinatorial synthetic method, which allows for the generation of
large sublibraries containing hundreds to thousands of analogs with designed
diversity.
 
                                       40

<PAGE>
    We have also assembled a collection of over 1,000 compounds with known
effects on the central nervous system, which we refer to as our reference drugs.
These compounds include many drugs that are currently used to treat various
diseases in psychiatry and neurology, and a host of other drugs and research
compounds that have important physiological effects on the brain. Our reference
drugs, when combined with our profiling capability, provide an important
resource to link clinical and physiological effects of drugs with genomic
targets.
 
    GENOMIC/PHARMACOLOGY DATABASE.  Using our evidence-based approach, our goal
is to measure the potency and efficacy of our reference drugs against a range of
genomic targets using our R-SAT system. Through these efforts, we are seeking to
generate an extensive set of central nervous system, or CNS, drug/gene product
interactions that will reside in our genomic/pharmacology database. Because the
majority of current CNS drugs were discovered before their genetic targets were
identified, the molecular mechanisms of their therapeutic and adverse effects
are poorly understood. We believe that by combining our database with existing
clinical knowledge, our evidence-based approach will result in important
correlations between gene/drug interactions and clinical responses. Our database
also contains information on proprietary chemistries that target individual gene
products. These chemistries provide tool compounds for the validation of genomic
targets and starting points for our drug discovery programs.
 
    LEAD OPTIMIZATION AND PRECLINICAL DEVELOPMENT.  The properties of a lead
compound must generally be improved before selection of a development candidate
for further preclinical testing and clinical development. Using our R-SAT
system, we evaluate the pharmacology of new analogs IN VITRO. This high
throughput pharmacology capability provides our scientists with a powerful tool
to streamline the lead optimization process, removing a traditional bottleneck
in the drug discovery process. We complement this pharmacology capability by our
strength in combinatorial and medicinal chemistry, which allows for the design
and production of a large number of optimized analogs. Sufficiently potent,
efficacious and selective compounds are further evaluated using standard
pharmacological models, pivotal disease models, and relevant gene knockout
animal models. We have established expertise in drug metabolism and
pharmacokinetics, including bioanalytical chemistry, which allows us to
efficiently optimize the properties of our drug candidates. We complement our
internal pharmacology and preclinical development capabilities through
collaborations with leading academic laboratories and clinical research
organizations.
 
    PHARMACOGENOMICS.  We are applying our integrated technology platform to the
area of pharmacogenomics using two approaches. The first approach seeks to
leverage proprietary information concerning the genomic targets of many
neuropsychiatric drugs. We sequence these specific targets in populations of
patients with relevant neuropsychiatric diseases. As we identify genetic
variations in these targets, we are testing the consequences of these variations
on the functional and pharmacological effects of relevant neuropsychiatric
drugs. Our second approach applies our functional genomics technology to the
analysis of genes isolated from individual patients. The functional and
pharmacological effects of drugs can be evaluated using patient DNA as a
starting point. By using this approach, we believe that potential differences in
therapeutic response and toxicity may be predicted prior to a patient's initial
exposure to a drug. Together, these approaches will provide a broad insight
concerning the influence that variation in genomic targets has on the clinical
responses to many neuropsychiatric drugs.
 
COLLABORATION AGREEMENTS
 
    We have established and intend to continue to pursue both licensing and
development collaborations and functional genomics collaborations with
pharmaceutical and biotechnology companies to commercialize our integrated drug
candidates and our technology platform. Our collaborations may include up front
payments at initiation of the collaboration, research support during
 
                                       41

<PAGE>
the discovery term, milestone payments upon successful completion of specified
development milestones, and royalties based upon sales, if any, of drugs
developed under the collaboration. Our current collaboration agreements are as
follows:
 
    ALLERGAN, INC.
 
    LICENSING AND DEVELOPMENT COLLABORATION.  In July 1999, we entered into a
license and collaboration agreement with Allergan, a global health care company
providing eye care and specialty pharmaceutical products. This collaboration
provides for the development and commercialization of drugs for glaucoma based
on our proprietary and gene product specific muscarinic lead compounds. Under
the agreement, we provide our expertise in medicinal chemistry and high
throughput pharmacology for a two year period to enable the selection of up to
two development candidates for clinical development and commercialization by
Allergan. Allergan was granted worldwide rights to products based on our lead
compounds for the treatment of ocular disease. In exchange, we are eligible to
receive up to approximately $19 million for the first development candidate, in
the form of up front fees, research support and milestone payments. We will also
receive royalties on future product sales, if any. Allergan also has the right
to select a second development candidate, subject to similar milestone and
royalty payments to us. The funding and collaborative activities under the
license and collaboration agreement, as renewed, will cease in July 2001, unless
extended by the parties. The agreement itself terminates six months after the
later of ten years from the date of the first sale of the final commercial
product developed under the agreement or the expiration of the last patent to
expire covering a product developed under the agreement. The agreement may be
terminated earlier by Allergan upon 90 days' notice to us, by mutual agreement
of the parties, or by either party in the event of a breach by the other party
or upon the other party's bankruptcy or insolvency.
 
    FUNCTIONAL GENOMICS COLLABORATION.  In September 1997, we established a
three year collaboration agreement with Allergan to work jointly and exclusively
on target validation and discovery efforts on several potential drug targets.
This collaboration was extended in September 2000 for an additional two year
period. Allergan has exclusive development and commercialization rights to all
therapeutic uses, with the exception that we retain development rights to at
least one therapeutic indication for each target. Under the collaboration, we
receive research funding. We are also eligible to receive milestone payments of
up to $12.5 million for the first product developed for each target as well as
royalties on sales of products, if any, resulting from the collaboration. The
funding and collaborative activities under the collaboration agreement, as
renewed, will cease in September 2002. The agreement itself terminates six
months after the later of ten years from the date of the first sale of the final
commercial product developed under the agreement or the expiration of the last
patent to expire covering a product developed under the agreement. The agreement
may be terminated earlier by mutual agreement of the parties, by either party in
the event of a breach by the other party or upon the other party's bankruptcy or
insolvency, or by Allergan in the event of a change in control of our company.
In September 1997, Allergan also made a $6 million equity investment in our
company.
 
    ARQULE, INC.
 
    LICENSING AND DEVELOPMENT COLLABORATIONS.  In December 2000, we entered into
a five year collaborative drug discovery agreement with ArQule, Inc, a company
engaged in the discovery, development and production of novel chemical compounds
primarily for the pharmaceutical, biotechnology and agrochemical industries.
This collaboration is focused on the discovery of drug candidates for selected
genomic targets and replaces an earlier material transfer and screening
agreement. Under the collaboration, we will combine our integrated technology
platform with ArQule's Parallel Track Drug Discovery Program to discover novel
small molecule drug candidates directed at individual genomic targets. We will
share equally in all future revenues created by our joint discovery programs,
including future milestone, royalty and upfront payments resulting from the out
licensing of
 
                                       42

<PAGE>
drug candidates, if any, and we will each obtain selected rights to pursue
independent discovery efforts. The collaborative drug discovery agreement
terminates in December 2005. However, the agreement may be terminated earlier by
mutual agreement of the parties, by either party upon 90 days' notice to the
other party, or by either party after a deadlock of the steering committee for
the collaboration that lasts 60 days.
 
    In May 2000, we entered into a compound license agreement with ArQule. Under
this agreement, we obtained rights to specified ArQule compounds discovered in
our earlier material transfer and screening agreement in exchange for milestones
and royalties. The compound license agreement terminates six months after the
latest date upon which ArQule could receive royalties or fees under the
agreement. However, the agreement may be terminated earlier by either us or
ArQule in the event of a material breach by the other party.
 
    PAREXEL INTERNATIONAL CORPORATION.
 
    FUNCTIONAL GENOMICS COLLABORATION.  In November 2000, we entered into a
collaboration agreement with PAREXEL International Corporation, a leading
clinical research, medical marketing and consulting services organization,
designed to provide pharmacogenomic services to pharmaceutical companies using
our integrated technology platform. Under the agreement, PAREXEL will make our
pharmacogenomics capabilities and expertise available to potential
pharmaceutical customers engaged in clinical trials of drugs for
neuropsychiatric disease. We will seek to enter into agreements with these
customers to provide our services, including research to identify the genomic
targets of their neuropsychiatric drugs in clinical development and how these
targets may vary functionally in patient populations. We will be required to
make specified payments to PAREXEL based upon the revenues earned under these
agreements with pharmaceutical partners, if any. The initial term of the
collaborative agreement expires in November 2003, but will be automatically
renewed for additional one year periods unless we or PAREXEL object to a renewal
with 90 days' notice to the other party.
 
INTELLECTUAL PROPERTY
 
    We will be able to protect our technology from unauthorized use by third
parties only to the extent that it is covered by valid and enforceable patents
or are effectively maintained as trade secrets. Accordingly, patents or other
proprietary rights are an essential element of our business. We have three
issued patents and nine pending patent applications in the United States
covering novel target-specific small molecule drug candidates. In addition, we
have received patents in 13 foreign countries on our R-SAT technology and have
16 foreign patent applications and one international patent application pending
that cover our R-SAT technology or novel compounds identified using this
technology. Our policy is to file patent applications to protect technology,
inventions and improvements to inventions that are commercially important to the
development of our business. We seek United States and international patent
protection for a variety of technologies, including: new screening and chemistry
methodologies and other research tools; targeting mechanisms that are associated
with disease states identified in our screens; and lead compounds that interact
with these other targets. We also intend to seek patent protection or rely upon
trade secret rights to protect other technologies that may be used to discover
and validate targets and that may be used to identify and develop novel drugs.
We seek protection, in part, through confidentiality and proprietary information
agreements. We are a party to various other license agreements that give us
rights to use technologies in our research and development.
 
COMPETITION
 
    We face, and will continue to face, intense competition from pharmaceutical
and biotechnology companies, as well as numerous academic and research
institutions and governmental agencies, both in the United States and abroad. We
compete with existing and new products being developed by our
 
                                       43

<PAGE>
competitors. Some of our competitors are using functional genomics technologies
or other methods to identify and validate drug targets and to discover novel
small molecule drugs. Some of these competitors are pursuing the development of
pharmaceuticals that target the same diseases and conditions that our research
programs target. Many of our competitors and their collaborators have
significantly greater experience than we do in the following:
 
    - identifying and validating targets;
 
    - screening compounds against targets;
 
    - preclinical and clinical trials of potential pharmaceutical products; and
 
    - obtaining FDA and other regulatory clearances.
 
    In addition, many of our competitors and their collaborators have
substantially greater advantages in the following areas:
 
    - capital resources;
 
    - research and development resources;
 
    - manufacturing;
 
    - sales and marketing; and
 
    - production facilities.
 
    Smaller companies also may prove to be significant competitors, particularly
through proprietary research discoveries and collaborative arrangements with
large pharmaceutical and established biotechnology companies. Many of our
competitors have products that have been approved or are in advanced
development. We face competition from other companies, academic institutions,
governmental agencies and other public and private research organizations for
collaborative arrangements with pharmaceutical and biotechnology companies, in
recruiting and retaining highly qualified scientific and management personnel
and for licenses to additional technologies.
 
    Our competitors, either alone or with their collaborators, may succeed in
developing technologies or drugs that are more effective, safer, more affordable
or more easily administered than ours and may achieve patent protection or
commercialize drugs sooner than us. Developments by others may render our
product candidates or our technologies obsolete. Our failure to compete
effectively could have a material adverse effect on our business.
 
GOVERNMENT REGULATION
 
    The manufacturing and marketing of our potential products and our ongoing
research and development activities are subject to extensive regulation by
numerous governmental authorities in the United States and other countries.
Before marketing in the United States, any drug developed by us must undergo
rigorous preclinical testing and clinical trials and an extensive regulatory
clearance process implemented by the FDA under the federal Food, Drug, and
Cosmetic Act. The FDA regulates, among other things, the development, testing,
manufacture, safety, efficacy, record keeping, labeling, storage, approval,
advertising, promotion, sale and distribution of biopharmaceutical products.
None of our product candidates has been approved for sale in the United States
or any foreign market. The regulatory review and approval process, which
includes preclinical testing and clinical trials of each product candidate, is
lengthy, expensive and uncertain. Securing FDA approval requires the submission
of extensive preclinical and clinical data and supporting information to the FDA
for each indication to establish a product candidate's safety and efficacy. The
approval process takes many years, requires the expenditure of substantial
resources, involves postmarketing surveillance, and may involve ongoing
requirements for postmarketing studies. Before commencing clinical
investigations in humans, we or
 
                                       44

<PAGE>
our collaborators must submit to, and receive approval from, the FDA of an
Investigational New Drug application. We have in the past and may in the future
rely on some of our collaborators to file Investigational New Drug applications
and generally direct the regulatory approval process for many of our potential
products.
 
    Clinical testing must meet requirements for institutional review board
oversight, informed consent and good clinical practices. Clinical testing must
be conducted under FDA oversight. Before receiving FDA clearance to market a
product, we or our collaborators must demonstrate that the product is safe and
effective on the patient population that will be treated. If regulatory
clearance of a product is granted, this clearance will be limited to those
disease states and conditions for which the product is useful, as demonstrated
through clinical studies. Marketing or promoting a drug for an unapproved
indication is generally prohibited. Furthermore, clearance may entail ongoing
requirements for postmarketing studies. Even if this regulatory clearance is
obtained, a marketed product, its manufacturer and its manufacturing facilities
are subject to continual review and periodic inspections by the FDA. Discovery
of previously unknown problems with a product, manufacturer or facility may
result in restrictions on this product or manufacturer, including costly recalls
or withdrawal of the product from the market.
 
    Any drug is likely to produce some toxicities or undesirable side effects in
animals and in humans when administered at sufficiently high doses and/or for
sufficiently long periods of time. Unacceptable toxicities or side effects may
occur at any dose level at any time in the course of studies in animals designed
to identify unacceptable effects of a drug candidate, known as toxicological
studies, or clinical trials of our potential products. The appearance of any
unacceptable toxicity or side effect could cause us or regulatory authorities to
interrupt, limit, delay or abort the development of any of our product
candidates and could ultimately prevent their clearance by the FDA or foreign
regulatory authorities for any or all targeted indications.
 
    We and our collaborators and contract manufacturers are also are required to
comply with the applicable FDA current good manufacturing practice regulations.
Good manufacturing practice regulations include requirements relating to quality
control and quality assurance as well as the corresponding maintenance of
records and documentation. Manufacturing facilities are subject to inspection by
the FDA. These facilities must be approved before we can use them in commercial
manufacturing of our products. We or our collaborators or contract manufacturers
may not be able to comply with the applicable good manufacturing practice
requirements and other FDA regulatory requirements. If we or our collaborators
or contract manufacturers fail to comply, our business, financial condition and
results of operations may be materially adversely affected.
 
    Outside the United States, our collaborator's ability to market a product is
contingent upon receiving a marketing authorization from the appropriate
regulatory authorities. The requirements governing the conduct of clinical
trials, marketing authorization, pricing and reimbursement vary widely from
country to country. At present, foreign marketing authorizations are applied for
at a national level, although within the European Community, or EC, registration
procedures are available to companies wishing to market a product in more than
one EC member state. If the regulatory authority is satisfied that adequate
evidence of safety, quality and efficacy has been presented, a marketing
authorization will be granted. This foreign regulatory approval process involves
all of the risks associated with FDA clearance discussed above.
 
MARKETING, SALES & MANUFACTURING
 
    We currently have no marketing, sales, distribution or manufacturing
capabilities. In order to commercialize any of our product candidates, we must
make arrangements with our collaborators or other third parties to provide these
services or internally develop these capabilities. Our agreements with Allergan
call for Allergan to provide these services and to arrange for the manufacture
of
 
                                       45

<PAGE>
sufficient quantities of our product candidates for use in preclinical and
clinical trials. Our future programs may be conducted independently or with a
collaborator who does not provide these services, in which case we will be
required to retain contract manufacturers for our product candidates or obtain
from third parties the components of product candidates and bulk chemical
materials. In the event that we elect to manufacture any of our future products
internally, we will have to add manufacturing facilities and personnel. In the
event we choose to market any of our future products directly, we must develop a
marketing and sales force with technical expertise and with supporting
distribution capabilities.
 
EMPLOYEES
 
    At November 30, 2000, we had 89 full time employees, of whom 34 hold Ph.D.
and/or other advanced degrees. Of our total workforce, 74 are engaged in
research and development activities and 15 are engaged in business development,
finance and administration. None of our employees is represented by a collective
bargaining agreement, nor have we experienced work stoppages. We believe that
our relations with our employees are good.
 
FACILITIES
 
    Our primary facilities consist of approximately 34,000 square feet of
research and office space located in San Diego, California that is leased to us
until 2005. We have an option to renew this lease for one additional period of
5 years. We also have approximately 14,500 square feet of research and office
space located in Glostrup, Denmark leased until 2002. We believe that our
existing facilities are adequate for our current needs. When our leases expire,
we may look for additional or alternate space for our operations and we believe
that suitable additional or alternative space will be available in the future on
commercially reasonable terms.
 
LEGAL PROCEEDINGS
 
    We are not currently a party to any legal proceedings.
 
                                       46

<PAGE>
SCIENTIFIC ADVISORY BOARD
 
    We utilize scientists and physicians to advise us on scientific and medical
matters as part of our Scientific Advisory Board, or SAB, including experts in
human genetics, mouse genetics, molecular biology, biochemistry, cell biology,
chemistry, pharmacology, structural biology and pharmaceutical discovery and
development. Generally, each of our scientific consultants has received an
option to purchase shares of our common stock.
 
    TAMAS BARTFAI, PH.D. is Director of the Harold L. Dorris Neurological
Research Center at the Scripps Research Institute of La Jolla, California and
holds the Harold L. Dorris Chair in Neuroscience. He also holds the chair of
Medical Chemistry at the Karolinska Institute, Stockholm. His more than
27 years of experience in neuroscience includes both academic and pharmaceutical
settings. Until recently, he was Head of Central Nervous System research at
Hoffmann-La Roche, Basel. Much of his professional career was spent as a
professor at Stockholm University, most recently as the Chairman of the
Department of Neurochemistry and Neurotoxicity. His expertise extends into the
areas of peptide neurobiology and muscarinic acetylcholine receptors and he has
made significant contributions to understanding the molecular and biochemical
basis of cognition and the molecular basis of fever and other neuroinflammatory
states. He has been involved in the development of several central nervous
system drugs in neurology and psychiatry as consultant to major pharmaceutical
corporations.
 
    HENRY BOURNE, M.D. has made significant contributions to the understanding
of the signaling pathways used by GPCRs. Dr. Bourne's research has focused on
transmembrane signaling mediated by G proteins, and his research played a key
role in identifying the role of cyclic AMP, or cAMP, in cellular function. His
laboratory studies also characterized various unique G protein subunits, which
define distinct signaling pathways within the cell. He is Professor of Medicine
and Pharmacology and a Senior Staff Member of the Cardiovascular Research
Institute at the University of California at San Francisco. He is a member of
the National Academy of Sciences and a Fellow of the American Association for
the Advancement of Science, and he is on the Board of Reviewing Editors of
SCIENCE magazine.
 
    ARVID CARLSSON, M.D., PH.D. is the most recent winner of the Nobel Prize in
medicine. He is Professor Emeritus of Pharmacology at University of Goteborg,
Sweden, and is a member of the Royal Swedish Academy of Sciences and a foreign
associate member of the US National Academy of Sciences. Dr. Carlsson's research
has changed the understanding of the molecular basis of several major
neuropsychiatric diseases, including Parkinson's disease, depression and
schizophrenia. He is an author on several hundred peer reviewed journal articles
and the recipient of numerous awards, including the Nobel Prize, the Japan Prize
in Psychology and Psychiatry, The Research Prize of the Lundbeck Foundation in
Denmark and the Lieber Prize for research in schizophrenia in the United States.
 
    MARC G. CARON, PH.D. is James B. Duke Professor of Cell Biology and Medicine
at Duke University Medical Center and Investigator at Howard Hughes Medical
Institute. His research focuses on the molecular study of receptors for
neurotransmitters and hormones. He is the recipient of numerous awards such as
the DuPont Prize for Receptor Research and the Javits Neuroscience Award.
Dr. Caron has served on editorial boards of a number of journals including
JOURNAL OF BIOLOGICAL CHEMISTRY and MOLECULAR PHARMACOLOGY. He is currently
Associate Editor in Chief of ENDOCRINE REVIEWS and Associate Editor of
BIOCHEMISTRY.
 
    ROBERT E. DAVIS, PH.D. is a consultant to our company. Previously, he was
President and Chief Scientific Officer of MitoKor, a development stage
biopharmaceutical company. Earlier in his career, Dr. Davis served as Director
of Neurodegenerative Diseases Research at Warner-Lambert Company where he was
instrumental in the development of Cognex, the first FDA approved therapy for
Alzheimer's disease. Dr. Davis serves on the editorial board of NEUROBIOLOGY OF
AGING, CURRENT OPINIONS IN INVESTIGATIONAL DRUGS and EMERGING THERAPEUTICS. His
awards include the National Research Award
 
                                       47

<PAGE>
from the National Institute of Alcohol Abuse and Alcoholism and the Leadership
in Research Award from the Alzheimer Association.
 
    BRIAN KOBILKA, M.D. is Professor of Medicine and Molecular and Cellular
Physiology at Stanford University Medical School. He is also an Associate
Investigator of the Howard Hughes Medical Institute. Dr. Kobilka is an expert in
the study of adrenergic receptor function. He has received several awards,
including the Syntex Prize in Receptor Pharmacology, the John Jacob Abel Award
from the American Society for Pharmacology and Experimental Therapeutics, and
the Young Investigator Award from the Western Society for Clinical
Investigation.
 
    LESLIE L. IVERSEN, PH.D. is also a member of our clinical advisory board and
is the chairman of our board of directors. For a description of his scientific
background, please see "Management."
 
    POVL KROGSGAARD-LARSEN, PH.D. is also a member of our board of directors.
For a description of his scientific background, please see "Management."
 
CLINICAL ADVISORY BOARD
 
    In addition to our SAB, we utilize a number of scientists and physicians to
advise us on scientific and medical matters as part of our Clinical Advisory
Board. Generally, each of our clinical advisors has received an option to
purchase shares of our common stock.
 
    ALLAN I. LEVEY, M.D., PH.D. is Professor of Neurology, Psychiatry and
Behavioral Sciences and Pharmacology at Emory University and Vice-Chairman of
the Department of Neurology. He is also Director of the Emory Center for
Neurodegenerative Diseases and the Alzheimer's Disease Center. Dr. Levey has
done extensive research in the molecular neurobiology of Alzheimer's and
Parkinson's diseases including animal models, diagnostics and clinical trials.
He has received numerous awards, including the Alzheimer's Association Faculty
Scholar Award, the Derek Denny-Brown Neurological Scholar Award from the
American Neurological Association and the Heikkila Research Scholar Award from
the National Parkinson Foundation.
 
    HERBERT Y. MELTZER, M.D., is Bixler Professor of Psychiatry and Pharmacology
and Director of the Division of Psychopharmacology at the Vanderbilt University
School of Medicine. Dr. Meltzer's major research interests are the
neurochemistry and psychopharmacologic treatment of schizophrenia, the mechanism
of action of antipsychotic drugs, and suicide and cognitive studies in
schizophrenic patients. His awards include the Daniel Efron Research Award of
the American College of Neuropsychopharmacology, the Lieber Prize from NARSAD,
Stanley Dean Award of the American College of Psychiatry and the Gold Medal
Award of the Society of Biological Psychiatry, the Research Prize of the
American Foundation for Suicide Prevention, the Paul Hoch Distinguished Service
Award from the American College of Neuropsychopharmacology, the Sachar Award
from Columbia University and the Kobe Award from the Commonwealth of
Pennsylvania. Dr. Meltzer is President-elect of the Collegium Internationale
Neuropsychopharmacologicum and past president of the American College of
Neuropsychopharmacology.
 
    CHARLES NEMEROFF, M.D., PH.D. is currently the Reunette W. Harris Professor
and Chairman of the Department of Psychiatry and Behavioral Sciences at Emory
University. His research has concentrated on the biological basis of the major
neuropsychiatric disorders, including affective disorders, Alzheimer's disease,
schizophrenia, and anxiety disorders. His numerous honors include the Gold Medal
Award from the Society of Biological Psychiatry, the Research Prize from the
American Psychiatric Association, the Selo Prize from the National Alliance for
Research in Schizophrenia and Depression and the Research Award in Mood
Disorders from the American College of Psychiatrists. Dr. Nemeroff is past
President of the American College of Neuropsychopharmacology.
 
    ARVID CARLSSON, M.D., PH.D. is also a member of our scientific advisory
board. For his scientific background, please see "Scientific Advisory Board."
 
    LESLIE L. IVERSEN, PH.D. is also a member of our scientific advisory board
and is the chairman of our board of directors. For a description of his
scientific background, please see "Management."
 
                                       48

<PAGE>

                                   MANAGEMENT
 
EXECUTIVE OFFICERS AND DIRECTORS
 
    Set forth below is the name, age, position and a brief account of the
business experience of each of our executive officers and directors.
 

<TABLE>
<CAPTION>
NAME                                          AGE      POSITION
----                                        --------   --------
<S>                                         <C>        <C>
Uli Hacksell, Ph.D........................     50      Chief Executive Officer and Director
Mark R. Brann, Ph.D.......................     42      President, Chief Scientific Officer and
                                                       Director
Thomas H. Aasen...........................     40      Vice President, Chief Financial Officer,
                                                         Secretary and Treasurer
Leslie L. Iversen, Ph.D...................     63      Director and Chairman of the Board
Thomas Eklund(1)..........................     33      Director
Arne J. Gillin(1).........................     43      Director
Carl L. Gordon, Ph.D., CFA(1)(2)..........     36      Director
Lester J. Kaplan, Ph.D., D.Sc.(2).........     50      Director
Povl Krogsgaard-Larsen, Ph.D..............     59      Director
Torsten Rasmussen(2)......................     56      Director
</TABLE>

 
------------------------
 
(1) Member of the audit committee.
 
(2) Member of the compensation committee.
 
    ULI HACKSELL, PH.D. joined us as our Executive Vice President of Drug
Discovery in February 1999 and was elected Chief Executive Officer in
September 2000. He became a member of our board of directors in October 2000.
From August 1991 to February 1999, Dr. Hacksell held various senior executive
positions at Astra, a pharmaceutical company, including Vice President of Drug
Discovery and Technology as well as President of Astra Draco, one of Astra's
largest research and development subsidiaries, where he directed an organization
of more than 1,100 employees. From August 1991 to May 1994, he served as Vice
President of CNS Preclinical R&D at Astra Arcus, another subsidiary. Earlier in
his career, Dr. Hacksell held the positions of professor of Organic Chemistry
and Chairman at Uppsala University in Sweden and also served as Chairman and
Vice Chairman of the European Federation of Medicinal Chemistry. Dr. Hacksell
received a Master of Pharmacy and a Ph.D. in Medicinal Chemistry at Uppsala
University.
 
    MARK R. BRANN, PH.D. is our founder and has served as our President and
Chief Scientific Officer and a member of our board of directors since January
1997. Prior to founding our company and from 1991 to 1996, Dr. Brann was a
tenured Associate Professor at the University of Vermont. He also directed a
research group at the National Institutes of Health, where he received the
Boehringer award for his accomplishments in identifying and characterizing
muscarinic receptor genes. He is on the editorial boards of two international
scientific journals and is also an Adjunct Associate Professor at the University
of California, San Diego. Dr. Brann received his Ph.D. in Pharmacology from the
University of Vermont.
 
    THOMAS H. AASEN has served as our Vice President, Chief Financial Officer,
Secretary and Treasurer since April 1998. From June 1996 to April 1998,
Mr. Aasen held the position of Senior Director of Finance and Administration at
Axys Pharmaceuticals, formerly called Sequana Therapeutics, Inc. From
October 1991 to June 1996, he served as Director of Finance at Genta, Inc., a
life sciences company. Earlier in his career, Mr. Aasen held various financial
positions including Director of Accounting at Gen-Probe, Inc., a life sciences
company, and Audit Manager at KPMG Peat Marwick. He has eighteen years of
professional finance and accounting experience focused primarily on the life
sciences industry. Mr. Aasen received his B.S. degree with honors from San Diego
State University and is a Certified Public Accountant.
 
                                       49

<PAGE>
    LESLIE L. IVERSEN, PH.D. has served as a director of our company since
April 1998 and is a founding member of our Scientific Advisory Board.
Dr. Iversen was elected Chairman of our board of directors in December 2000.
Since 1999, Dr. Iversen has been a Professor of Pharmacology at King's College,
London and Director of the Wolfson Centre for Age Related Diseases. Since 1995,
he has also served as a Visiting Professor at the Department of Pharmacology,
University of Oxford. Dr. Iversen is internationally recognized for his
fundamental contributions to the understanding of neurotransmission. He is a
Fellow of the Royal Society of London and a Foreign Associate Member of the US
National Academy of Sciences. From 1987 to 1995, Dr. Iversen acted as
Vice-President for Neuroscience for Merck Research Laboratories, the research
division of the leading international pharmaceutical company Merck & Co., Inc.
and, also served as served as Director of the Neuroscience Center of Merck
Research Laboratories in the UK from 1983 to 1995. In addition, he was Director
of the Medical Research Council, Neurochemical Pharmacology Unit in Cambridge
from 1970 to 1983. In 1995, Dr. Iversen founded Panos Therapeutics and currently
serves as one of its directors. He received his Ph.D. and B.A. from the
University of Cambridge.
 
    THOMAS EKLUND has served as a director of our company since September 2000.
Since June 2000, Mr. Eklund has served as Investment Director of Alfred Berg ABN
AMRO AB Capital Investment AB, a company organized in Sweden and majority owned
by ABN AMRO NV, Netherlands. From June 1992 to May 2000, he had various
positions within the Investment Banking division of Handelsbanken, a Swedish
universal banking group, including the last three years as Vice President and
head of the life science team within corporate finance. Mr. Eklund holds an
M.B.A. from Stockholm School of Economics.
 
    ARNE GILLIN has served on our board of directors since January 1997. Since
1993, he has been Vice President of Dansk Kapitalanlaeg, the largest venture
capital firm in Denmark. Prior to joining Dansk Kapitalanlaeg, Mr. Gillin's
experience included serving as Chief Controller for Volund A/S and as Department
Manager for Centralanstalten for Revision/KPMG C. Jespersen, an auditing
company. Mr. Gillin also serves on the boards of directors of several other
biopharmaceutical and technology companies. He is a State Authorized Public
Accountant in Denmark.
 
    CARL L. GORDON, PH.D., CFA has served as a director of our company since
June 2000. Since January 1998, Dr. Gordon has been a General Partner of OrbiMed
Advisors LLC, a leading institutional healthcare investor. Prior to joining
OrbiMed and from March 1995 to December 1997, Dr. Gordon was with Mehta and
Isaly, where he was a Senior Analyst covering biotechnology. Dr. Gordon was a
Fellow at The Rockefeller University. He received a Ph.D. in molecular biology
from the Massachusetts Institute of Technology and a B.A. degree from Harvard
University.
 
    LESTER J. KAPLAN, PH.D., D.SC. has served as a director of our company since
November 1997. Dr. Kaplan is Corporate Vice President, Science & Technology and
President, Research & Development and Global BOTOX-Registered Trademark- and a
board member of Allergan, Inc. Dr. Kaplan joined Allergan in 1983 and, prior to
being appointed to his current position, was Corporate Vice President, Research
and Development from June 1992 to July 1996. Dr. Kaplan was elected to
Allergan's board of directors in 1994, and is a member of its Science and
Technology Committee. Dr. Kaplan is also a member of the board of directors of
Allergan Specialty Therapeutics, Inc., and an Advisory Board Member to the
Pediatric Cancer Research Foundation and Healthcare Ventures. Dr. Kaplan
received his M.S. and Ph.D. in organic chemistry from the University of
California, Los Angeles.
 
    POVL KROGSGAARD-LARSEN, PH.D. has served as a member of both our board of
directors and our Scientific Advisory Board since January 1997. Since 1986,
Dr. Krogsgaard-Larsen has been Professor of Medicinal Chemistry at the Royal
Danish School of Pharmacy and, from 1991 to 1992, was
F. Merz-Stiftungsgastprofessor at Goethe University in Frankfurt. He is a
medicinal chemist who specializes in the study of compounds for treatment of
neurological disorders. He serves on the board of directors of Carlsberg
Foundation as a trustee of the Alfred Benzon Foundation and is the recipient
 
                                       50

<PAGE>
of numerous awards such as the Astra Award, the Paul Erlich Prize and the W.Th.
Nauta Award. Dr. Krogsgaard-Larsen is a member of the Royal Danish Academy of
Sciences and Letters and the Danish Academy of Natural Sciences. He received his
Ph.D. and D.Sc. from the Royal Danish School of Pharmacy and honorary doctorates
from Louis Pasteur University and Uppsala University.
 
    TORSTEN RASMUSSEN has served as a director of our company since April 1998.
Mr. Rasmussen has been CEO of Morgan Management ApS, a management advisory and
consulting company, since 1997. Prior to founding Morgan Management ApS in 1997,
Mr. Rasmussen held the position of Executive Vice President, Operations at the
LEGO Group (LEGO A/S) in Denmark, since 1981. He currently serves as a board
member in the capacity of chairman, deputy chairman or ordinary board member of
a number of Danish companies of which the following are quoted on the Danish
Stock Exchange: Coloplast A/S, Bang & Olufsen A/S, TK Development A/S, Vestas
Wind Systems A/S, Vest-Wood A/S and A/S Det Oestasiatiske Kompagni.
Mr. Rasmussen holds an M.B.A. from IMD in Lausanne, Switzerland.
 
BOARD COMPOSITION
 
    Upon the closing of this offering, in accordance with the terms of our
certificate of incorporation, the terms of office of our board of directors will
be divided into three classes:
 
    - Class I directors, whose term will expire at the first annual meeting of
      stockholders following the closing of this offering;
 
    - Class II directors, whose term will expire at the second annual meeting of
      stockholders following the closing of this offering; and
 
    - Class III directors, whose term will expire at the third annual meeting of
      stockholders following the closing of this offering.
 
Our Class I directors will be Mr. Gillin, Dr. Iversen, and Mr. Eklund, our
Class II directors will be Dr. Kaplan, Dr. Brann and Mr. Rasmussen and our
Class III directors will be Dr. Gordon, Dr. Hacksell and Dr. Krogsgaard-Larsen.
At each annual meeting of stockholders, after the initial classification, the
successors to directors whose terms will then expire will be elected to serve
from the time of election and qualification until the third annual meeting
following election. Any additional directorships resulting from an increase in
the number of directors will be distributed among the three classes so that, as
nearly as possible, each class will consist of one third of the directors. This
classification of the board of directors may have the effect of delaying or
preventing a change of control or management of our company.
 
COMMITTEES OF THE BOARD OF DIRECTORS
 
    The audit committee of the board of directors reviews our internal
accounting procedures and consults with and reviews the services provided by our
independent accountants.
 
    Our compensation committee reviews and makes recommendations to the board
concerning compensation and benefits of all of our executive officers,
administers our stock option plans and establishes and reviews general policies
relating to compensation and benefits of our employees.
 
DIRECTOR COMPENSATION
 
    Our directors currently receive a cash retainer of $3,000 per year for
services on the board of directors or any committee thereof, and directors may
be reimbursed for expenses in connection with attendance at board and committee
meetings. In addition, all nonemployee directors are eligible to participate in
our 2000 nonemployee directors' stock option plan. However, if a nonemployee
director is not eligible to receive stock options by reason of the director's
obligations to the director's employer
 
                                       51

<PAGE>
or for any other reason, the director may elect to receive an additional cash
retainer of $7,000 for each year.
 
    Our 2000 nonemployee directors' stock option plan provides for automatic
stock option grants to nonemployee directors serving on the board. Each person
who is elected or appointed for the first time to be a nonemployee director
subsequent to the date of this offering will be granted an initial grant on the
date of his or her election or appointment to the board to purchase 12,000
shares of our common stock.
 
    The 2000 nonemployee directors' stock option plan also provides that
eligible nonemployee directors will, on the day following each annual meeting,
automatically receive an annual grant to purchase 3,000 shares of our common
stock commencing, as applicable, with the annual meeting in 2002. If, however,
the person has not been serving as a nonemployee director for the entire period
since the preceding annual meeting, the number of shares subject to the annual
grant will be reduced pro rata for each full month period prior to the date of
grant during which such person did not serve as a nonemployee director.
 
    The nonemployee director stock options will have a maximum term of ten years
and generally must be exercised prior to the earliest of 18 months following the
death of the nonemployee director, 12 months from the termination of service on
the board by the nonemployee director due to a disability, three months from the
termination of the service of the nonemployee director for any other reason, or
the expiration of the original term of the stock option. One third of the shares
issued under each initial grant of a nonemployee director option vest one year
after the date of grant and one twelfth vest on a quarterly basis over the next
two years. One quarter of the shares under each annual grant of a nonemployee
director option vest each month following the date of grant. All options granted
to nonemployee directors will be granted at the fair market value of the common
stock on the date of grant.
 
COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION
 
    None of our executive officers serves as a member of the board of directors
or compensation committee of any entity that has one or more executive officers
serving on our board of directors or compensation committee.
 
                                       52

<PAGE>

EXECUTIVE COMPENSATION
 
    The following table sets forth information concerning the compensation that
we will have paid during the fiscal year ended December 31, 2000, to our Chief
Executive Officer and each of our other executive officers whose salary and
bonus for the fiscal year exceeded $100,000 and who served as an executive
officer of ours during the fiscal year.
 
                           SUMMARY COMPENSATION TABLE
 

<TABLE>
<CAPTION>
                                                                           LONG-TERM
                                                                          COMPENSATION
                                                                          ------------
                                                  ANNUAL COMPENSATION      SECURITIES
                                                 ----------------------    UNDERLYING     ALL OTHER
NAME AND PRINCIPAL POSITION                       SALARY        BONUS       OPTIONS      COMPENSATION
---------------------------                      --------      --------   ------------   ------------
<S>                                              <C>           <C>        <C>            <C>
Uli Hacksell, Ph.D. ...........................  $237,944(1)   $55,310       100,000       $  8,500(2)
  Chief Executive Officer
 
Mark R. Brann, Ph.D. ..........................   223,478       44,696            --          8,500(2)
  President and Chief Scientific Officer
 
Thomas H. Aasen ...............................   184,026       48,500        35,000          8,500(2)
  Vice President and Chief Financial Officer
 
Leonard R. Borrmann, Pharm.D. .................   174,559           --            --        166,297
  Former Chief Executive Officer(3)
</TABLE>

 
------------------------
 
(1) Dr. Hacksell's salary reflects amounts paid to him as our Executive Vice
    President before becoming our Chief Executive Officer in September 2000, and
    amounts paid to him as Chief Executive Officer after September 2000.
 
(2) Represents matching contribution of $8,500 paid by us to the account of
    these executive officers in our 401(k) Plan.
 
(3) Dr. Borrmann resigned as our Chief Executive Officer effective
    September 20, 2000. Amounts under "All Other Compensation" include a
    matching contribution of $8,500 paid by us to the account of Dr. Borrmann in
    our 401(k) Plan and an aggregate of $157,797 in payments to Mr. Borrmann in
    connection with his separation from us, including continuation of salary,
    bonus and accrued vacation.
 
EMPLOYMENT AGREEMENTS AND INDEBTEDNESS OF MANAGEMENT
 
    ULI HACKSELL, PH.D.  We entered into an employment letter agreement with Uli
Hacksell, Ph.D. dated December 21, 1998, providing for an initial annual salary
of $212,835, subject to adjustment from time to time, plus bonuses based upon
Dr. Hacksell's individual performance and our financial performance as
determined by our board of directors, a signing bonus of $75,000 and an
opportunity to acquire 200,000 shares of our common stock under our 1997 stock
option plan. Dr. Hacksell's employment letter agreement also provided for
reimbursement of specified expenses incurred by Dr. Hacksell in connection with
his relocation to San Diego, California in an amount not to exceed $100,000.
Under the terms of the agreement, Dr. Hacksell's stock options will become fully
vested upon a change of control of our company. In September 2000, Dr. Hacksell
was promoted from Executive Vice President of Drug Discovery to the position of
Chief Executive Officer and his annual salary was raised to $275,000. If we
terminate Dr. Hacksell's employment for reasons other than cause, the employment
letter agreement obligates us to pay Dr. Hacksell a severance of the
continuation of his salary and other benefits he may be receiving at the time of
termination for the one year period following his termination.
 
                                       53

<PAGE>
    In May 2000, we loaned $100,000 to Dr. Hacksell to assist with the purchase
of a residence in connection with his relocation to San Diego, California. Under
the terms of a Secured Promissory Note dated May 11, 2000, the principal amount
of the loan plus accrues interest at prime and will be due and payable at the
end of four years, or earlier in the event of a termination of employment.
 
    MARK R. BRANN, PH.D.  We entered into an employment agreement with Mark R.
Brann, Ph.D. dated January 31, 1997, providing for an initial annual salary of
$160,000, subject to adjustment from time to time, plus bonuses to be paid
solely at the discretion of our board of directors based on Dr. Brann's
achievement of reasonable, measurable performance objectives established by our
board of directors at the beginning of each fiscal year. The agreement obligates
us, following a termination of Dr. Brann's employment under select
circumstances, to pay Dr. Brann a severance of the continuation of his salary
and other benefits he may be receiving at the time of termination for the two
year period following his termination.
 
    THOMAS H. AASEN.  We entered into an employment letter agreement with Thomas
H. Aasen, dated March 4, 1998, providing for an initial annual salary of
$160,000, subject to adjustment from time to time, plus bonuses based upon
Mr. Aasen's individual performance and our financial performance as determined
by our board of directors, a signing bonus of $20,000 and an opportunity to
acquire 75,000 shares of common stock under our 1997 stock option plan. Under
the terms of the agreement, Mr. Aasen's stock options will become fully vested
upon a change of control of our company. If we terminate Mr. Aasen's employment
for reasons other than cause, we are obligated to pay Mr. Aasen a severance of
the continuation of his salary and other benefits he may be receiving at the
time of termination for the one year period following his termination.
 
    LEONARD R. BORRMANN, PHARM.D.  We entered into an employment letter
agreement with Leonard R. Borrmann, Pharm.D., dated April 17, 1998, providing
for an initial annual salary of $220,000, subject to adjustment from time to
time, plus bonuses to be paid solely at the discretion of our board of directors
based on Dr. Borrmann's achievement of reasonable, measurable performance
objectives established by our board of directors at the beginning of each fiscal
year, a signing bonus of $50,000 and an opportunity to acquire 300,000 shares of
our common stock under our 1997 stock option plan. Dr. Borrmann resigned as our
Chief Executive Officer effective September 20, 2000. In connection with his
resignation, we entered into a separation agreement with Dr. Borrmann that
provided for the continuation of salary for an additional year from the date of
his resignation, the payment of a bonus for the period of service in 2000 and
cash payment of accrued vacation time. The agreement also provides for the
acceleration of vesting of options to purchase 31,250 shares of our common stock
and that all of Dr. Borrmann's options will remain exercisable until
September 2007.
 
OPTION GRANTS IN 2000
 
    The following table sets forth, as to the named executive officers,
information concerning stock options granted to purchase shares of our common
stock under our 1997 stock option plan during the fiscal year ended
December 31, 2000. Except as otherwise noted below, 25% of the option vests on
the one year anniversary of employment and the remainder vest in a series of
equal monthly installments beginning on the month following the one year
anniversary of employment and continuing over the next three years of service.
The percentage of total options is based upon options to purchase an aggregate
of 398,250 granted to employees under our 1997 stock option plan in 2000.
 
    Amounts represent the hypothetical gains that could be achieved from the
respective options if exercised at the end of the option term and are not
predictive of our future gains, if any. These gains are based on assumed rates
of stock appreciation of 5% and 10% compounded annually from the date
 
                                       54

<PAGE>
the respective options were granted to their expiration date based upon an
initial public offering price of $      , minus the applicable per share
exercise price.
 

<TABLE>
<CAPTION>
                                                      INDIVIDUAL GRANTS                    POTENTIAL REALIZABLE
                                     ---------------------------------------------------     VALUE AT ASSUMED
                                     NUMBER OF    PERCENTAGE OF                                ANNUAL RATES
                                     SECURITIES   TOTAL OPTIONS                               OF STOCK PRICE
                                     UNDERLYING    GRANTED TO     EXERCISE                     APPRECIATION
                                      OPTIONS     EMPLOYEES IN    PRICE PER   EXPIRATION   ---------------------
NAME                                  GRANTED      FISCAL YEAR      SHARE        DATE         5%          10%
----                                 ----------   -------------   ---------   ----------   ---------   ---------
<S>                                  <C>          <C>             <C>         <C>          <C>         <C>
Uli Hacksell, Ph.D................    100,000         25.1%         $1.00     10/01/2010
Mark R. Brann, Ph.D...............         --           --             --             --         --          --
Thomas H. Aasen...................     35,000          8.8           1.00      6/28/2010
Leonard R. Borrmann, Pharm.D......         --           --             --             --         --          --
</TABLE>

 
2000 YEAR END OPTION VALUES
 
    The following table sets forth information concerning stock options to
purchase common stock held at December 31, 2000 by each of the named executive
officers.
 

<TABLE>
<CAPTION>
                                                          NUMBER OF
                                                    SECURITIES UNDERLYING         VALUE OF UNEXERCISED
                                                     UNEXERCISED OPTIONS         IN THE MONEY OPTIONS AT
                                                    AT DECEMBER 31, 2000          DECEMBER 31, 2000(1)
                                                 ---------------------------   ---------------------------
NAME                                             EXERCISABLE   UNEXERCISABLE   EXERCISABLE   UNEXERCISABLE
----                                             -----------   -------------   -----------   -------------
<S>                                              <C>           <C>             <C>           <C>
Uli Hacksell, Ph.D.............................     91,667        208,333        $              $
Mark R. Brann, Ph.D............................     62,500        137,500
Thomas H. Aasen................................     50,000         60,000
Leonard R. Borrmann, Pharm.D.(2)...............    200,000             --                             --
</TABLE>

 
------------------------
 
(1) There was no public trading market for our common stock at December 31,
    2000. Accordingly, these values have been calculated on the basis of the
    assumed initial public offering price of $      per share minus the
    applicable per share exercise price.
 
(2) At the time of Dr. Borrmann's resignation, he held options to purchase
    200,000 shares of our common stock that are exercisable and will remain
    exercisable until September 20, 2007 under the terms of his separation
    agreement.
 
EMPLOYEE BENEFIT PLANS
 
    1997 STOCK OPTION PLAN.  In January 1997, we adopted our 1997 stock option
plan. A total of 2,700,000 shares of common stock are authorized for issuance
under the 1997 stock option plan, as amended in April 1999 and November 2000.
Shares subject to stock options that have expired or otherwise terminated
without having been exercised in full again become available for grant.
 
    The 1997 stock option plan permits the grant of options to our directors,
officers, other employees and consultants. Options may be either incentive stock
options to employees within the meaning of Section 422 of the Internal Revenue
Code or nonstatutory stock options. Except in specified circumstances, no person
may be granted options covering more than 500,000 shares of common stock in any
calendar year.
 
    The 1997 stock option plan is administered by the board of directors. The
board may delegate the authority to administer the plan to a committee of
directors or to one or more executive officers. In connection with this
offering, the board will designate the compensation committee to administer the
plan. Subject to the limitations set forth in the plan or limitations created by
the board, the administrator has the authority to select the eligible persons to
whom option grants are to be made, to
 
                                       55

<PAGE>
designate the number of shares to be covered by each option, to determine
whether an option is to be an incentive stock option or a nonstatutory stock
option, to establish vesting schedules, to specify the exercise price of options
and the type of consideration to be paid upon exercise and, subject to specified
restrictions, to specify other terms of option grants under the plan.
 
    The maximum term of options granted under the plan is ten years. Options
granted under the 1997 stock option plan are generally nontransferable. Options
granted under the 1997 stock option plan vest at the rate determined by the
administrator as specified in the option agreement.
 
    In the event of an acquisition event amounting to a change in control of our
ownership as defined in the 1997 stock option plan, our board of directors has
the discretion to provide that all outstanding stock options under the plan may
be assumed or substituted by the surviving entity. As an alternative or in
addition, our board may provide that outstanding options will become exercisable
in full at a specified date prior to the change of control and that all
unexercised options will terminate immediately prior to the change of control.
In addition, options granted to our employees in Denmark under the 1997 stock
option plan require the option holders, in some circumstances, to sell all of
their shares and other securities of our company upon request by a group of our
major stockholders under our amended and restated stockholders agreement on
terms negotiated between those major stockholders and the proposed buyer.
 
    Our board of directors may amend or terminate the 1997 stock option plan at
any time. Amendments will generally be submitted for stockholder approval to the
extent required by applicable law.
 
    At November 30, 2000, we had issued and outstanding under the 1997 stock
option plan options to purchase 1,483,404 shares of common stock and 397,117
shares had been purchased upon the exercise of previously held options. The
exercise prices for each of these outstanding options ranges from $0.01 per
share to $1.50 per share.
 
    2000 EQUITY INCENTIVE PLAN.  In December 2000, we adopted our 2000 equity
incentive plan. A total of 3,300,000 shares of common stock will be authorized
for issuance under the plan and the 1997 stock option plan. There are 2,902,883
shares reserved for issuance under the 2000 equity incentive plan subject to
reduction for shares exercised under our 1997 stock option plan. The plan
includes an "evergreen" provision providing that an additional number of shares
will automatically be added annually to the shares authorized for issuance under
the plan and the 1997 stock option plan. The number of shares added at our
annual meeting each year beginning in 2002 will be equal to the least of:
 
    - five percent of our outstanding capital stock as of the record date for
      the applicable annual meeting;
 
    - 1,500,000; and
 
    - an amount determined for such year by our board of directors.
 
Shares subject to stock awards that have expired or otherwise terminated without
having been exercised in full again become available for grant.
 
    The 2000 equity incentive plan permits the grant of options to our
directors, officers, other employees and consultants. Options may be either
incentive stock options to employees within the meaning of Section 422 of the
Internal Revenue Code or nonstatutory stock options. In addition, the plan
permits the grant of stock bonuses and rights to purchase restricted stock.
Except in specified circumstances, no person may be granted options covering
more than 1,000,000 shares of common stock in any calendar year.
 
                                       56

<PAGE>
    The 2000 equity incentive plan is administered by the board of directors or
a committee appointed by the board. Subject to the limitations set forth in the
plan, the committee has the authority to select the eligible persons to whom
award grants are to be made, to designate the number of shares to be covered by
each award, to determine whether an option is to be an incentive stock option or
a nonstatutory stock option, to establish vesting schedules, to specify the
exercise price of options and the type of consideration to be paid upon exercise
and, subject to specified restrictions, to specify other terms of awards.
 
    The maximum term of any option granted under the plan is ten years.
Incentive stock options granted under the plan are generally nontransferable.
Nonstatutory stock options are generally nontransferable, although the
applicable option agreement may permit some transfers. Options generally expire
three months after the termination of an optionholder's service. However, if an
optionholder is permanently disabled, or dies, during his or her service, that
person's options generally may be exercised up to 12 months following disability
or up to 18 months following death.
 
    The exercise price of options granted under the 2000 equity incentive plan
will be determined by the board of directors or committee in accordance with the
guidelines set forth in the plan. The exercise price of an incentive stock
option cannot be less than 100% of the fair market value of the common stock on
the date of grant. The exercise price of a nonstatutory stock option generally
cannot be less than 85% of the fair market value of the common stock on the date
of grant.
 
    Options granted under the plan vest at the rate determined by the board of
directors or committee as specified in the option agreement. The terms of any
stock bonuses or restricted stock purchase awards granted under the plan will be
determined by the board of directors or committee. The purchase price of
restricted stock under any restricted stock purchase agreement will be
determined by the board of directors or committee and will not be less than 85%
of the fair market value of our common stock on the date of grant. Stock bonuses
and restricted stock purchase agreements awarded under the plan will generally
be nontransferable, although the applicable award agreement may permit some
transfers.
 
    In the event of a corporate transaction amounting to a change of control in
our ownership as defined in the 2000 equity incentive plan, all outstanding
stock awards under the plan must either be assumed or substituted for by the
surviving entity. In the event the surviving entity does not assume or
substitute for the stock awards, then the vesting and exercisability of
outstanding awards will accelerate prior to the change of control and the awards
will terminate to the extent not exercised prior to the change of control.
 
    The board of directors may amend or terminate the 2000 equity incentive plan
at any time. Amendments will be submitted for stockholder approval to the extent
required by applicable law.
 
    The 2000 equity incentive plan will take effect upon the consummation of
this offering.
 
    2000 NONEMPLOYEE DIRECTORS' STOCK OPTION PLAN.  In December 2000, we adopted
our 2000 nonemployee directors' stock option plan. A total of 200,000 shares of
common stock are authorized for issuance under the plan. Shares subject to stock
awards that have expired or otherwise terminated without having been exercised
in full again become available for grant.
 
    The plan permits the grant of options to our nonemployee directors. Options
under the 2000 nonemployee directors' stock option plan may only be nonstatutory
stock options. See also the discussion under " --Director Compensation"
regarding automatic grants to nonemployee directors under the plan and the terms
of those grants.
 
    The plan is administered by the board of directors. Subject to the
limitations set forth in the plan, the board has the authority to construe and
interpret the plan and options granted under it, and to
 
                                       57

<PAGE>
establish, amend and revoke rules and regulations for its administration and to
specify the terms of options granted under the plan.
 
    In the event of a corporate transaction amounting to a change of control in
our ownership as defined in the 2000 nonemployee directors' stock option plan,
all outstanding stock awards under the plan must either be assumed or
substituted by the surviving entity. In the event the surviving entity does not
assume or substitute for the stock awards, then the vesting and exercisability
of outstanding awards will accelerate prior to the change of control and the
awards will terminate to the extent not exercised prior to the change of
control. Amendments to the plan will generally be submitted for stockholder
approval to the extent required by applicable law.
 
    The 2000 nonemployee directors' stock option plan will take effect upon
completion of this offering.
 
    2000 EMPLOYEE STOCK PURCHASE PLAN.  In December 2000, we adopted the 2000
employee stock purchase plan. A total of 150,000 shares of common stock has been
reserved for issuance under the purchase plan. The plan includes an "evergreen"
provision providing that an additional number of shares will automatically be
added annually to the shares authorized for issuance under the plan. The number
of shares added at our annual stockholder meeting each year beginning in 2002
will be the least of:
 
    - one percent of our outstanding capital stock;
 
    - 250,000; and
 
    - an amount expressly determined for such year by our board of directors.
 
    The purchase plan is intended to qualify as an employee stock purchase plan
within the meaning of Section 423 of the Internal Revenue Code. Under the
purchase plan, the board of directors may authorize participation by eligible
employees, including executive officers, in periodic offerings following the
commencement of the purchase plan. The initial offering under the purchase plan
will commence on the effective date of this offering and continue for two years
thereafter.
 
    Unless otherwise determined by the board of directors, employees are
eligible to participate in the purchase plan only if they are employed by us or
one of our subsidiaries designated by the board of directors for at least 20
hours per week and are customarily employed for at least five months per
calendar year. Employees who participate in an offering may have up to 15% of
their earnings withheld pursuant to the purchase plan. The amount withheld is
then used to purchase shares of common stock on specified dates determined by
the board of directors. The price of common stock purchased under the purchase
plan will be equal to 85% of the lower of the fair market value of the common
stock at the commencement date of each offering period or the relevant purchase
date. Employees may end their participation in the offering at any time during
the offering period, and participation ends automatically upon termination of
employment.
 
    In the event of a merger, reorganization, consolidation or liquidation, or
other change of control, each right to purchase common stock will be assumed or
an equivalent right substituted by the successor corporation. In the event that
the rights are not assumed or substituted, then all sums collected by payroll
deductions will be applied to purchase stock immediately prior to such merger or
other transaction. The board of directors has the authority to amend or
terminate the purchase plan, provided however, that no such action may adversely
affect any outstanding rights to purchase common stock.
 
    The 2000 employee stock purchase plan will take effect upon completion of
this offering.
 
    401(k) PLAN.  We adopted a 401(k) Plan effective January 1, 1997. All
regular employees who are 21 years or older, with the exception of post doctoral
training fellows and graduate student training
 
                                       58

<PAGE>
fellows, are eligible to participate in the plan on the first day of January,
April, July or October following their date of hire. These participants may
contribute up to 15% of their current compensation, subject to a statutorily
prescribed annual dollar limit set by the IRS. Participant contributions are
held in a trust as required by law. Individual participants may direct the
trustee to invest their accounts in authorized investment alternatives. We make
matching contributions to the 401(k) Plan on behalf of each participant in an
amount equal to 100% of the participant's salary reduction contributions up to
5% of the participant's annual compensation. In addition, we may make
discretionary and special contributions each year, although we have not done so
to date. Each participant is fully vested in his or her salary reduction
contributions and our matching and special contributions to the 401(k) Plan. We
adopted the Safe Harbor Contribution Plan Amendment in January 1999. The 401(k)
Plan is intended to qualify under Section 401(a) of the Internal Revenue Code so
that contributions to the 401(k) Plan, and income earned on such contributions,
are not taxable to participants until withdrawn or distributed from the 401(k)
Plan.
 
                                       59

<PAGE>

                           RELATED PARTY TRANSACTIONS
 
    The following is a description of transactions since January 1, 1997 to
which we have been a party and in which any director, executive officer or
holder of more than 5% of our capital stock had or will have a direct or
indirect material interest, other than compensation arrangements, which are
described under "Management." See "Principal Stockholders" for more detail
regarding the relationship of these parties to our directors, executive offers
and principal stockholders.
 
    The following executive officer and principal stockholders purchased
securities in the amounts and on the dates shown:

<TABLE>
<CAPTION>
                                    SERIES A    SERIES B    SERIES C    SERIES D     SERIES E
                         COMMON     PREFERRED   PREFERRED   PREFERRED   PREFERRED   PREFERRED
PURCHASER                 STOCK     STOCK(1)    STOCK(2)    STOCK(3)    STOCK(4)     STOCK(5)    WARRANTS(6)   WARRANTS(7)
---------               ---------   ---------   ---------   ---------   ---------   ----------   -----------   -----------
<S>                     <C>         <C>         <C>         <C>         <C>         <C>          <C>           <C>
EXECUTIVE OFFICER
 
Mark R. Brann, Ph.D.,
  President, Chief
  Scientific Officer
  and Director(9).....  1,523,088         --          --           --         --            --         --            --
 
PRINCIPAL STOCKHOLDERS
 
Danske Kapitalanlaeg
  Aktieselskab(10)....     58,824    588,235     176,471           --    185,000       400,000     58,824        58,824
 
Kommunernes
  Pensionsforsikring
  A/S(10).............     58,824    588,235     176,471           --    185,000       400,000     58,824        58,824
 
Lonmodtagernes
  Dyrtidsfond(10).....     58,824    588,235     176,471           --    185,000       266,667     58,824        58,824
 
BankInvest
  affiliates(10)......     58,824    588,235     176,471           --         --            --     58,824        58,824
 
Allergan Sales,
  Inc.................         --         --          --    1,000,000         --            --         --            --
 
ABN AMRO Ventures
  B.V.................         --         --          --           --    750,000            --         --            --
 
OrbiMed Advisors LLC
  affiliates..........         --         --          --           --         --       666,667         --            --
 
Hambrecht & Quist
  Capital Management,
  Inc. and
  affiliates..........         --         --          --           --         --       666,667         --            --
 
S.V. Penelope Jones,
  Ph.D.(11)...........    147,936         --          --           --         --            --         --            --
 
OTHER TRANSACTION
  INFORMATION
 
Price per share.......    Various    $  2.55     $  4.00    $    6.00    $  6.75    $     7.50         --            --
 
Date(s) of purchase...    Various       2/97        8/97         9/97       8/98    5/00, 6/00       2/97          2/97
 
<CAPTION>
 
PURCHASER               WARRANTS(8)
---------               -----------
<S>                     <C>
EXECUTIVE OFFICER
Mark R. Brann, Ph.D.,
  President, Chief
  Scientific Officer
  and Director(9).....        --
PRINCIPAL STOCKHOLDERS
Danske Kapitalanlaeg
  Aktieselskab(10)....    41,607
Kommunernes
  Pensionsforsikring
  A/S(10).............    41,607
Lonmodtagernes
  Dyrtidsfond(10).....    41,607
BankInvest
  affiliates(10)......    41,607
Allergan Sales,
  Inc.................    33,151
ABN AMRO Ventures
  B.V.................        --
OrbiMed Advisors LLC
  affiliates..........        --
Hambrecht & Quist
  Capital Management,
  Inc. and
  affiliates..........        --
S.V. Penelope Jones,
  Ph.D.(11)...........        --
OTHER TRANSACTION
  INFORMATION
Price per share.......        --
Date(s) of purchase...      3/98
</TABLE>

 
------------------------
 
 (1) In February 1997, we sold in a private placement 2,372,548 shares of
     Series A preferred stock in exchange for an aggregate purchase price of
     $6,049,997 in cash. The shares of Series A preferred stock were sold under
     a Series A preferred stock purchase agreement dated February 3, 1997. Upon
     the closing of this offering, each share of Series A preferred stock will
     be converted into one share of common stock.
 
 (2) In August 1997, we sold in a private placement 738,384 shares of Series B
     preferred stock in exchange for an aggregate purchase price of $2,953,536
     in cash. The shares of Series B preferred stock were sold under a Series B
     preferred stock purchase agreement dated August 12, 1997.
 
                                       60

<PAGE>
     Upon the closing of this offering, each share of Series B preferred stock
     will be converted into one share of common stock.
 
 (3) In September 1997, we sold in a private placement 1,000,000 shares of
     Series C preferred stock to Vision Pharmaceuticals L.P., now Allergan
     Sales, Inc., in exchange for an aggregate purchase price of $6,000,000 in
     cash. The shares of Series C preferred stock were sold under a stock
     purchase agreement dated September 24, 1997. Upon the closing of this
     offering, each share of Series C preferred stock will be converted into one
     share of common stock.
 
 (4) In August 1998, we sold in a private placement 1,581,653 shares of
     Series D preferred stock in exchange for an aggregate purchase price of
     $10,676,158 in cash. The shares of Series D preferred stock were sold under
     a Series D preferred stock purchase agreement dated August 26, 1998. Upon
     the closing of this offering, each share of Series D preferred stock will
     be converted into one share of common stock.
 
 (5) In May and June 2000, we sold in a private placement 2,933,335 shares of
     Series E preferred stock in exchange for an aggregate purchase price of
     $22,000,013 in cash. The shares of Series E preferred stock were sold under
     a Series E preferred stock purchase agreement dated May 5, 2000. Upon the
     closing of this offering, each share of Series E preferred stock will be
     converted into one share of common stock.
 
 (6) In February 1997 in connection with our Series A preferred stock financing,
     we issued warrants to purchase an aggregate of 237,257 shares of our common
     stock at an exercise price of $6.00 per share, which warrants were
     exercised in December 1997.
 
 (7) In February 1997 in connection with our Series A preferred stock financing,
     we issued warrants to purchase an aggregate of 237,257 shares of our common
     stock at an exercise price of $12.00 per share, which warrants remain
     unexercised. These warrants expire in February 2002.
 
 (8) In March 1998, we issued warrants to purchase an aggregate of 202,043
     shares of our common stock at an exercise price of $15.00 per share. These
     warrants expired in June 2000.
 
 (9) The shares of common stock acquired by Dr. Brann were issued upon our
     reincorporation in January 1997 in Delaware. We were previously
     incorporated in Vermont. Dr. Brann originally acquired 250 shares of common
     stock of the Vermont corporation for $250 in cash, which shares were
     exchanged for the shares of our common stock described above. 687,575
     shares of common stock were subsequently transferred by Dr. Brann to S.V.
     Penelope Jones, Ph.D.
 
 (10) The shares of common stock purchased by these stockholders and their
      affiliates were issued in December 1997 upon the exercise of the warrants
      described in footnote (6) above.
 
 (11) The shares of common stock acquired by Dr. Jones were issued upon the
      exercise of stock options granted under our 1997 stock option plan at an
      aggregate exercise price of $1,479.
 
    We entered into other agreements in connection with the purchases of our
preferred stock described above. Under one of these agreements, our amended and
restated stockholders agreement, some of our stockholders acquired registration
rights. See "Description of Capital Stock--Registration Rights" for a
description of these registration rights. Further, we agreed with our
stockholders on restrictions on the issuance and transfer of shares of our
capital stock, rights of first refusal, voting rights relating to the election
of directors and provisions requiring all parties to the agreement to sell their
shares if requested by a group of major stockholders, all of which restrictions
and rights are not applicable to, and will terminate upon the closing of, this
offering. Similarly, our purchase agreement with Vision Pharmaceuticals L.P.,
now Allergan Sales, Inc., included a right of first refusal which is not
applicable to, and will terminate upon the closing of, this offering.
 
                                       61

<PAGE>
    In January and February 1999 and in connection with our Series A preferred
stock financing, Dr. Brann assigned his intellectual property rights relating to
mass drug screening and related technology to us.
 
    In July 1999, we entered into a collaborative research, development and
license agreement with Allergan, Inc., Allergan Sales, Inc. and Allergan
Pharmaceuticals (Ireland) Limited, Inc., related to our muscarinic glaucoma
program. In September 1997, we entered into a collaboration research,
development and license agreement with Allergan, Inc. and Vision Pharmaceuticals
L.P., now Allergan Sales, Inc., related to our functional genomics and discovery
efforts. One provision of the September 1997 agreement grants Allergan limited
rights of negotiation in the event of a proposed acquisition of our company. For
a more detailed discussion of our agreements with Allergan, refer to
"Business--Collaborations."
 
    Mr. Eklund, a member of our board of directors, held various positions from
June 1992 to May 2000 within the Investment Banking division of Handelsbanken, a
Swedish universal banking group. In August 1998, Handelsbanken served as
placement agent in our Series D preferred stock financing and received a
placement agent fee of $413,000.
 
    Dr. Iversen, a member of our board of directors, and his wife, Susan
Iversen, Ph.D., are currently employed by Oxford University. Oxford University
has provided pharmacology services to us from time to time. From January 1, 1997
through November 30, 2000, we have paid an aggregate of $71,600 to Oxford
University in consideration for services.
 
    S.V. Penelope Jones, Ph.D. was formerly employed by us. From November 3,
1997 through December 4, 1998, the date of her termination, we paid an aggregate
of $101,727 in salary and bonus to Dr. Jones. On December 4, 1998, we entered
into an agreement with Dr. Jones under which she provided cellular physiology
and other scientific consulting services to us. From December 4, 1998 to
December 3, 1999, we paid an aggregate of $93,500 to Dr. Jones in consideration
of these services. Dr. Jones is currently a professor at the University of
California, San Diego, or UCSD. UCSD provides laboratory services to us under
the terms of a services agreement. From December 1, 1999 through November 30,
2000, we have paid an aggregate of $50,000 to UCSD in consideration for
services.
 
    Some of our directors are associated with our major stockholders as
indicated in the table below:
 

<TABLE>
<CAPTION>
DIRECTOR                                        MAJOR STOCKHOLDER(S)
--------                      ---------------------------------------------------------
<S>                           <C>
Thomas Eklund..............   ABN AMRO Ventures B.V.
Arne J. Gillin.............   Danske Kapitalanlaeg Aktieselskab
Carl L. Gordon, Ph.D.......   OrbiMed Advisors LLC affiliates
Leslie L. Iversen, Ph.D....   BankInvest affiliates
Lester J. Kaplan, Ph.D.....   Allergan Sales, Inc.
Torsten Rasmussen..........   Kommunernes Pensionsforsikring A/S and Lonmodtagernes
                              Dyrtidsfond
</TABLE>

 
    We expect to enter into indemnification agreements with each of our
directors and executive officers.
 
                                       62

<PAGE>
                             PRINCIPAL STOCKHOLDERS
 
    Except as otherwise noted, the following table sets forth selected
information known to us with respect to beneficial ownership of our common stock
at November 30, 2000 by:
 
    - each stockholder we know to be the beneficial owner of more than five
      percent of our common stock;
 
    - each of our directors;
 
    - each of our named executive officers; and
 
    - all of our executive officers and directors as a group.
 
    Except where otherwise indicated below, the address of the stockholders
listed below is our address, 3911 Sorrento Valley Boulevard, San Diego,
California 92121.
 
    The following table reflects the number of shares of our common stock
outstanding at November 30, 2000 and the automatic conversion of all outstanding
shares of our convertible preferred stock into 8,625,920 shares of common stock.
 

<TABLE>
<CAPTION>
                                                                               PERCENTAGE OF SHARES
                                                                                BENEFICIALLY OWNED
                                                  NUMBER OF SHARES      -----------------------------------
NAME OF BENEFICIAL OWNER                        BENEFICIALLY OWNED(1)   BEFORE OFFERING   AFTER OFFERING(2)
------------------------                        ---------------------   ---------------   -----------------
<S>                                             <C>                     <C>               <C>
5% STOCKHOLDERS
Danske Kapitalanlaeg Aktieselskab(3)..........        1,467,354               13.5%
Kommunernes Pensionsforsikring A/S(4).........        1,467,354               13.5
Lonmodtagernes Dyrtidsfond(5).................        1,334,021               12.3
Allergan Sales, Inc. affiliates(6)............        1,000,000                9.3
BankInvest affiliates(7)......................          882,354                8.1
S.V. Penelope Jones, Ph.D.(8).................          835,511                7.7
ABN AMRO Ventures B.V.(9).....................          750,000                7.0
Hambrecht & Quist Capital Management,
  Inc.(10)....................................          666,667                6.2
OrbiMed Advisors LLC affiliates(11)...........          666,667                6.2
 
DIRECTORS AND EXECUTIVE OFFICERS
Uli Hacksell, Ph.D.(12).......................           95,833                  *
Mark R. Brann, Ph.D.(13)......................        1,589,755               14.7
Thomas H. Aasen(14)...........................           51,563                  *
Leslie L. Iversen, Ph.D.(7)(15)...............            8,500                  *
Torsten Rasmussen(4)(5)(16)...................            4,000                  *
Arne J. Gillin(3).............................        1,469,354               13.5
Lester J. Kaplan, Ph.D.(6)....................        1,006,000                9.3
Thomas Eklund(9)..............................          750,000                7.0
Carl L. Gordon, Ph.D.(11).....................          666,667                6.2
Povl Krogsgaard-Larsen, Ph.D., D.Sc...........               --                  *
Leonard R. Borrmann, Pharm.D.(17).............          200,000                1.8
All current directors and executive officers
  as a group (10 persons)(18).................        5,641,672               50.1
</TABLE>

 
------------------------
 
*   Represents beneficial ownership of less than 1% of our outstanding common
    stock.
 
 (1) Unless otherwise indicated below, the persons and entities named in the
     table above have sole voting and sole investment power with respect to all
     shares beneficially owned, subject to community property laws where
     applicable. Shares of common stock subject to options or warrants that are
     currently exercisable or are exercisable within 60 days of November 30,
     2000 are
 
                                       63

<PAGE>
     deemed to be outstanding and to be beneficially owned by the person holding
     such options or warrants for the purpose of computing the percentage
     ownership of such person but are not treated as outstanding for the purpose
     of computing the percentage ownership of any other person.
 
 (2) See discussion under "Underwriting" regarding the overallotment option to
     the underwriters.
 
 (3) Reflects 1,408,530 shares owned by Dansk Kapitalanlaeg Aktieselskab and
     includes 58,824 shares issuable upon the exercise of stock warrants.
     Mr. Gillin is a Vice President of Dansk Kapitalanlaeg Aktieselskab and he
     disclaims beneficial ownership of shares in which he does not have a
     pecuniary interest. Included in the beneficially owned shares of
     Mr. Gillin are 2,000 shares issuable to him upon the exercise of stock
     options. The address for Dansk Kapitalanlg Aktieselskab is
     103 Gothersgade, P.O. Box 1080, Copenhagen K Denmark.
 
 (4) Reflects 1,408,530 shares owned by Kommunernes Pensionsforsikring A/S and
     includes 58,824 shares issuable upon the exercise of stock warrants.
     Mr. Rasmussen represents Kommunernes Pensionsforsikring A/S on our board of
     directors and disclaims beneficial ownership of shares in which he does not
     have a pecuniary interest. The address for Kommunernes Pensionsforsikring
     A/S is Krumptappen 2, 2500 Valby Denmark.
 
 (5) Reflects 1,275,197 shares owned by Lonmodtagernes Dyrtidsfond and includes
     58,824 shares issuable upon the exercise of stock warrants. Mr. Rasmussen
     represents Lonmodtagernes Dyrtidsfond on our board of directors and
     disclaims beneficial ownership of shares in which he does not have a
     pecuniary interest. The address for Lonmodtagernes Dyrtidsfond is
     Vendersgade 28, DK-1363, Copenhagen K Denmark.
 
 (6) Reflects 1,000,000 shares owned by Allergan Sales, Inc. Dr. Kaplan is
     President, Research and Development and Global BOTOX at Allergan, Inc., the
     parent company of Allergan Sales, Inc., and he disclaims beneficial
     ownership of shares in which he does not have a pecuniary interest.
     Included in the beneficially owned shares of Dr. Kaplan are 6,000 shares
     issuable to him upon the exercise of stock options. The address for
     Allergan Sales, Inc. is 2525 Dupont Drive, P.O. Box 19534, Irvine,
     California.
 
 (7) Reflects 411,764.5 shares owned by BankInvest 7 Biotechnology and 411,765.5
     shares owned by BankInvest 1 Danske Aktier, and includes a total of 58,824
     shares issuable upon the exercise of stock warrants. Dr. Iversen represents
     BankInvest 7 Biotechnology and BankInvest 1 Danske Aktier on our board of
     directors and disclaims beneficial ownership of shares in which he does not
     have a pecuniary interest. The address for both BankInvest 7 Biotechnology
     and BankInvest 1 Danske Aktier is Toldbodgade 33, P.O. Box 9011, DK-22,
     Copenhagen K Denmark.
 
 (8) 687,575 of the shares held by Dr. Jones are subject to the terms of a
     voting agreement that permits Dr. Brann to direct the voting of the shares.
 
 (9) Reflects 750,000 shares owned by ABN AMRO Ventures B.V. Mr. Eklund is
     Investment Director of Alfred Berg ABN AMRO AB Capital Investment AB, a
     company majority owned by ABN AMRO N.V., and he disclaims beneficial
     ownership of shares in which he does not have a pecuniary interest. The
     address for ABN AMRO Ventures B.V. is Foppingadreof 22, Amsterdam,
     P.O. Box 283, 1000 EA Amsterdam, Netherlands.
 
 (10) Reflects 400,000 shares owned by H&Q Healthcare Investors and 266,667
      shares owned by H&Q Life Sciences Investors. Hambrecht and Quist Capital
      Management is the fund manager of H&Q Healthcare Investors and H&Q Life
      Sciences Investors. The address for Hambrecht and Quist Capital
      Management, Inc. is 50 Rowes Wharf, Boston, Massachusetts.
 
 (11) Reflects 400,000 shares owned by Eaton Vance Worldwide Health Sciences
      Fund and 266,667 shares owned by Finsbury Worldwide Pharmaceutical Trust.
      Dr. Gordon is a General Partner of
 
                                       64

<PAGE>
      OrbiMed Advisors LLC, which provides investment advisory services to Eaton
      Vance Worldwide Health Sciences Fund and Finsbury Worldwide Pharmaceutical
      Trust. Dr. Gordon disclaims beneficial ownership of shares in which he
      does not have a pecuniary interest. The address of OrbiMed Advisors LLC is
      767 Third Avenue, 6th Floor, New York, New York 10017-2023.
 
 (12) Reflects 95,833 shares issuable upon the exercise of stock options.
 
 (13) Reflects 835,513 shares held by Dr. Brann, 66,667 shares issuable upon the
      exercise of stock options and 687,575 shares held by Dr. Jones of which
      Dr. Brann has the power to direct the voting under the terms of a voting
      agreement. Dr. Brann disclaims beneficial ownership of shares subject to
      the voting agreement.
 
 (14) Reflects 51,563 shares issuable upon the exercise of stock options.
 
 (15) Reflects 8,500 shares issuable upon the exercise of stock options.
 
 (16) Reflects 4,000 shares issuable to Morgan Management ApS, a Danish
      corporation in which Mr. Rasmussen has a controlling interest, upon the
      exercise of stock options.
 
 (17) Reflects 200,000 shares issuable upon the exercise of stock options.
      Dr. Borrmann resigned as our Chief Executive Officer effective
      September 20, 2000.
 
 (18) Includes 234,563 shares issuable upon the exercise of stock options.
 
                                       65

<PAGE>

                          DESCRIPTION OF CAPITAL STOCK
 
    Following the closing of this offering, our authorized capital stock will
consist of 50,000,000 shares of common stock, $0.0001 par value per share, and
5,000,000 shares of preferred stock, $0.0001 par value per share. At
November 30, 2000, and assuming the conversion of all outstanding preferred
stock into common stock immediately prior to the closing of this offering there
were outstanding 10,783,382 shares of common stock held of record by 40
stockholders, warrants to purchase 237,257 shares of common stock and options to
purchase 1,483,404 shares of common stock.
 
COMMON STOCK
 
    Subject to preferences that may apply to shares of preferred stock
outstanding at the time, the holders of outstanding shares of common stock are
entitled to receive dividends out of assets legally available at such times and
in such amounts as our board of directors may from time to time determine. Each
stockholder is entitled to one vote for each share of common stock held on all
matters submitted to a vote of stockholders. Cumulative voting for the election
of directors is not provided for in our certificate of incorporation, which
means that the holders of a majority of the shares voted can elect all of the
directors then standing for election. The common stock is not entitled to
preemptive rights and is not subject to conversion or redemption. Each
outstanding share of common stock is, and all shares of common stock to be
outstanding upon completion of this offering will be, fully paid and
nonassessable.
 
PREFERRED STOCK
 
    Following the conversion of our outstanding preferred stock into common
stock in connection with this offering, our board of directors will have the
authority, without further action by the stockholders, to issue up to 5,000,000
shares of preferred stock in one or more series and to fix the designations,
powers, preferences, privileges, and relative participating, optional or special
rights and the qualifications, limitations or restrictions thereof, including
dividend rights, conversion rights, voting rights, terms of redemption and
liquidation preferences, any or all of which may be greater than the rights of
the common stock. Our board of directors, without stockholder approval, can
issue preferred stock with voting, conversion or other rights that could
adversely affect the voting power and other rights of the holders of common
stock. Preferred stock could thus be issued quickly with terms calculated to
delay or prevent a change of control or make removal of management more
difficult. The issuance of preferred stock may have the effect of decreasing the
market price of the common stock, and may adversely affect the voting and other
rights of the holders of common stock. At present, there are no shares of
preferred stock outstanding and we have no plans to issue any of the preferred
stock.
 
WARRANTS
 
    Upon completion of this offering, we will have outstanding warrants to
purchase an aggregate of 237,257 shares of common stock at an exercise price of
$12.00 per share. These warrants expire in February 2002 or on the occurrence of
specified events, whichever occurs first.
 
ANTI-TAKEOVER PROVISIONS
 
DELAWARE LAW
 
    We are governed by the provisions of Section 203 of the Delaware General
Corporation Law. In general, Section 203 prohibits a public Delaware corporation
from engaging in a "business combination" with an "interested stockholder" for a
period of three years after the date of the transaction in which the person
became an interested stockholder, unless the business combination is approved in
a prescribed manner. A "business combination" includes mergers, asset sales or
other transactions resulting in a financial benefit to the stockholder. An
"interested stockholder" is a person
 
                                       66

<PAGE>
who, together with affiliates and associates, owns, or within three years, did
own, 15% or more of the corporation's outstanding voting stock. This provision
could delay, discourage or prohibit transactions not approved in advance by the
board of directors, such as takeover attempts that might result in a premium
over the market price of the common stock.
 
CHARTER AND BYLAW PROVISIONS
 
    Our certificate of incorporation and bylaws contain provisions that could
discourage potential takeover attempts and make more difficult attempts by
stockholders to change management. Our certificate of incorporation provides
that stockholders may not take action by written consent but may only act at a
stockholders' meeting, and that special meetings of our stockholders may only be
called by the Chairman of our board of directors or a majority of our board of
directors.
 
REGISTRATION RIGHTS
 
    Following 180 days after the completion of this offering, under the terms of
our amended and restated stockholders agreement, the holders of 8,625,920 shares
of our common stock and warrants to purchase an aggregate of 237,257 shares of
our common stock will have the right to demand that we register their shares,
subject to limitations, under the Securities Act on Form S-1 or Form S-2 or
similar forms. In addition, at any time after we become eligible to file a
registration statement on Form S-3, these holders will have the right to demand
that we register their shares, subject to limitations, on Form S-3 or similar
form. In addition, these holders are entitled under the agreement, subject to
limitations, to require us to include their shares in future registration
statements that we may file for our own account or for the account of other
stockholders.
 
    We are generally required to bear all of the expenses of these
registrations, except underwriting discounts and commissions. Registration of
any of the shares of common stock entitled to these registration rights would
result in the shares becoming freely tradable without restriction under the
Securities Act. Upon completion of this offering, the registration rights with
respect to the shares held by any party to the amended and restated stockholders
agreement will terminate if the stockholder holds less than 1% of the then
outstanding shares of common stock and the stockholder's shares are entitled to
be resold without restriction under Rule 144 promulgated under the Securities
Act.
 
TRANSFER AGENT AND REGISTRAR
 
    The Transfer Agent and Registrar for our common stock is             .
 
                                       67

<PAGE>
                        SHARES ELIGIBLE FOR FUTURE SALE
 
    Prior to this offering, there has been no market for our common stock, and
we cannot assure you that a significant public market for the common stock will
develop or be sustained after this offering. Future sales of substantial amounts
of our common stock, including shares issued upon exercise of outstanding
options and warrants, in the public market after this offering could adversely
affect market prices prevailing from time to time and could impair our ability
to raise capital through sale of our equity securities. As described below, no
shares currently outstanding will be available for sale immediately after this
offering due to contractual restrictions on resale. Sales of substantial amounts
of our common stock in the public market after the restrictions lapse could
adversely affect the prevailing market price and our ability to raise equity
capital in the future.
 
    Upon completion of this offering, we will have outstanding
shares of common stock, assuming no exercise of the underwriters' overallotment
option and no exercise of outstanding options that do not expire upon the
closing. Of these shares, the             shares sold in this offering will be
freely tradable without restriction under the Securities Act unless purchased by
our "affiliates" as that term is defined in Rule 144 under the Securities Act.
The remaining             shares held by existing stockholders are subject to
various lockup agreements providing that, with limited exceptions, the
stockholder will not offer, sell, contract to sell, grant an option to purchase,
make a short sale or otherwise dispose of or engage in any hedging or other
transaction that is designed or reasonably expected to lead to a disposition of
any shares of common stock or any option to purchase shares of common stock or
any securities exchangeable for or convertible into shares of common stock for a
period of 180 days after public trading commences without the prior written
consent of Robertson Stephens, Inc. As a result of these lockup agreements,
notwithstanding possible earlier eligibility for sale under the provisions of
Rules 144, 144(k) and 701, none of these shares will be salable until 180 days
after the public trading commences. Beginning 180 days after public trading
commences,             of these shares will be eligible for sale in the public
market, although all but             shares will be subject to certain volume
limitations. Thereafter,             of these shares will become eligible for
sale between the end of the lockup period and       2001 and the remaining
      of these shares will become eligible for sale starting in 2002. In
addition, at               , 2001, there were outstanding options to purchase
            shares common stock. All of such options will be subject to lockup
agreements. Robertson Stephens, Inc. may, in its sole discretion and at any time
without notice, release all or any portion of the securities subject to lockup
agreements.
 
    In general, under Rule 144 as currently in effect, beginning 90 days after
the date of this prospectus, a person, or persons whose shares are aggregated,
who has beneficially owned unregistered shares for at least one year, including
the holding period of any prior owner except an affiliate, would be entitled to
sell within any three month period a number of shares that does not exceed the
greater of:
 
    - 1% of the number of shares of common stock then outstanding, which will
      equal approximately       shares immediately after this offering; or
 
    - the average weekly trading volume of the common stock during the four
      calendar weeks preceding the filing of a Form 144 with respect to such
      sale.
 
Sales under Rule 144 are also subject to specific manner of sale provisions and
notice requirements and to the availability of current public information about
us. Under Rule 144(k), a person who is not deemed to have been an affiliate of
us at any time during the three months preceding a sale, and who has
beneficially owned the shares proposed to be sold for at least two years,
including the holding period of any prior owner except an affiliate, is entitled
to sell such shares without complying with the manner of sale, public
information, volume limitation or notice provisions of Rule 144.
 
                                       68

<PAGE>
    Rule 701 permits resales of shares in reliance upon Rule 144 but without
compliance with specific restrictions, including the holding period requirement,
of Rule 144. Any of our employees, officers, directors or consultants who
purchased his or her shares pursuant to a written compensatory plan or contract
may be entitled to rely on the resale provisions of Rule 701. Rule 701 permits
affiliates to sell their Rule 701 shares under Rule 144 without complying with
the holding period requirements of Rule 144. Rule 701 further provides that
nonaffiliates may sell such shares in reliance on Rule 144 without having to
comply with the holding period, public information, volume limitation or notice
provisions of Rule 144. All holders of Rule 701 shares are required to wait
until 90 days after the date of this prospectus before selling such shares.
However, all shares issued pursuant to Rule 701 are subject to lockup agreements
and will only become eligible for sale at the earlier of the expiration of the
180 day lockup period or no sooner than 90 days after the offering upon
obtaining the prior written consent of Robertson Stephens, Inc.
 
                                       69

<PAGE>
               UNITED STATES TAX CONSEQUENCES TO NON-U.S. HOLDERS
 
    The following is a general discussion of the principal United States federal
income and estate tax consequences of the acquisition, ownership and disposition
of our common stock by a Non-U.S. Holder. As used in this prospectus, the term
"Non-U.S. Holder" is a person who holds our common stock other than:
 
    - a citizen or resident of the United States;
 
    - a corporation or other entity taxable as a corporation created or
      organized in or under the laws of the United States or of any political
      subdivision of the United States;
 
    - an estate the income of which is includable in gross income for United
      States federal income tax purposes regardless of its source; or
 
    - a trust subject to the primary supervision of a United States court and
      the control of one or more United States persons, or a trust (other than a
      wholly owned grantor trust) that was treated as a domestic trust despite
      not meeting the requirements described above.
 
    This discussion does not consider:
 
    - state, local or foreign tax consequences;
 
    - specific facts and circumstances that may be relevant to a particular
      Non-U.S. Holder's tax position in light of their particular circumstances;
 
    - the tax consequences for the stockholders or beneficiaries of a Non-U.S.
      Holder;
 
    - special tax rules that may apply to selected Non-U.S. Holders, including
      without limitation, partnerships, banks, insurance companies, dealers in
      securities and traders in securities; or
 
    - special tax rules that may apply to a Non-U.S. Holder that holds our
      common stock as part of a "straddle," "hedge" or "conversion transaction."
 
    The following discussion is based on provisions of the United States
Internal Revenue Code of 1986, as amended, also known as the Code, applicable
Treasury regulations and administrative and judicial interpretations, all as of
the date of this prospectus, and all of which are subject to change,
retroactively or prospectively. The following discussion assumes that our common
stock is held as a capital asset. The following summary is for general
information. Accordingly, each Non-U.S. Holder should consult a tax advisor
regarding the United States federal, state, local and foreign income and other
tax consequences of acquiring, holding and disposing of shares of our common
stock.
 
DIVIDENDS
 
    We do not anticipate paying cash dividends on our common stock in the
foreseeable future. See "Dividend Policy." In the event, however, that dividends
are paid on shares of our common stock, dividends paid to a Non-U.S. Holder of
our common stock generally will be subject to withholding of United States
federal income tax at a 30% rate, or such lower rate as may be provided by an
applicable income tax treaty.
 
    Dividends that are effectively connected with a Non-U.S. Holder's conduct of
a trade or business in the United States or, if any income tax treaty applies,
attributable to a permanent establishment in the United States, known as "United
States trade or business income," are generally subject to the 30% withholding
tax if the Non-U.S. Holder files the appropriate United States Internal Revenue
Service form with the payor. Any United States trade or business income received
by a Non-U.S. Holder that is a corporation may also, under limited
circumstances, be subject to an additional "branch profits tax" at a 30% rate or
such lower rate as specified by an applicable income tax treaty.
 
                                       70

<PAGE>
    Dividends paid prior to 2001 to an address in a foreign country are
presumed, absent actual knowledge to the contrary, to be paid to a resident of
such country for purposes of the withholding discussed above and for purposes of
determining the applicability of a tax treaty rate. For dividends paid after
2000, a Non-U.S. Holder of our common stock who claims the benefit of an
applicable income tax treaty rate generally will be required to satisfy
applicable certification and other requirements. Non-U.S. Holders should consult
their tax advisors regarding their entitlement to benefits under a relevant
income tax treaty.
 
    A Non-U.S. Holder of our common stock that is eligible for a reduced rate of
United States withholding tax under an income tax treaty may obtain a refund or
credit of any excess amounts withheld by filing an appropriate claim for a
refund with the United States Internal Revenue Service.
 
GAIN ON DISPOSITION OF COMMON STOCK
 
    A Non-U.S. Holder generally will not be subject to United States federal
income tax in respect of gain recognized on a disposition of our common stock
unless:
 
    - the gain is United States trade or business income, in which case the
      branch profits tax described above may apply to a corporate Non-U.S.
      Holder;
 
    - the Non-U.S. Holder is an individual who holds our common stock as a
      capital asset within the meaning of Section 1221 of the Code, is present
      in the United States for more than 182 days in the taxable year of the
      disposition and meets other requirements;
 
    - the Non-U.S. Holder is subject to tax pursuant to the provisions of the
      Untied States tax law applicable to selected United States expatriates; or
 
    - we are or have been a "United States real property holding corporation"
      for United States federal income tax purposes at any time during the
      shorter of the five-year period ending on the date of disposition or the
      period that the Non-U.S. Holder held our common stock.
 
    Generally, a corporation is a "United States real property holding
corporation" if the fair market value of its "United States real property
interest" equals or exceeds 50% of the sum of the fair market value of its
worldwide real property interests plus its other assets used or held for use in
a trade or business. We believe we have never been, are not currently and are
not likely to become a United States real property holding corporation for
United States federal income tax purposes.
 
FEDERAL ESTATE TAX
 
    Common stock owned or treated as owned by an individual who is a Non-U.S.
Holder at the time of death will be included in the individual's gross estate
for United States federal estate tax purposes, unless an applicable estate tax
or other treaty provides otherwise.
 
INFORMATION REPORTING AND BACKUP WITHHOLDING TAX
 
    We must report annually to the United States Internal Revenue Service and to
each Non-U.S. Holder the amount of dividends paid to that holder and the tax
withheld with respect to those dividends. Copies of the information returns
reporting those dividends and withholding may also be made available to the tax
authorities in the country in which the Non-U.S. Holder is a resident under the
provisions of an applicable income tax treaty or agreement.
 
    Under some circumstances, United States Treasury Regulations require
information reporting and backup withholding at a rate of 31% on specified
payments on our common stock. Under currently applicable law, Non-U.S. Holders
of our common stock, generally will be exempt from backup withholding on
dividends paid prior to 2001 to an address outside the United States. For
dividends paid after 2000, however, a Non-U.S. Holder of our common stock that
fails to certify its Non-U.S. Holder
 
                                       71

<PAGE>
status in accordance with applicable United States Treasury Regulations may be
subject to backup withholding at a rate of 31% of dividends.
 
    The payment of the proceeds of the disposition of our common stock by a
holder to or through the United States office of a broker generally will be
subject to information reporting and backup withholding at a rate of 31% unless
the holder either certifies its status as a Non-U.S. Holder under penalties of
perjury or otherwise establishes an exemption. The payment of the proceeds of
the disposition by a Non-U.S. Holder of our common stock to or through a foreign
office of a foreign broker will not be subject to backup withholding or
information reporting unless the foreign broker is a "United States related
person." In the case of the payment of proceeds from the disposition of our
common stock by or through a foreign office of a broker that is a United States
person or a "United States related person," information reporting, but currently
not backup withholding, on the payment applies unless the broker receives a
statement from the owner, signed under penalty or perjury, certifying its
foreign status or the broker has documentary evidence on its files that the
holder is a Non-U.S. Holder and the broker has no actual knowledge to the
contrary. For this purpose, a "United States related person" is:
 
    - a "controlled foreign corporation" for United States federal income tax
      purposes;
 
    - a foreign person 50% or more of whose gross income from all sources for
      the three-year period ending with the close of its taxable year preceding
      the payment, or for such part of the period that the broker has been in
      existence, is derived from activities that are effectively connected with
      the conduct of a United States trade or business;
 
    - effective after 2000, a foreign partnership if, at any time during the
      taxable year, (A) at least 50% of the capital or profits interest in the
      partnership is owned by United States persons, or (B) the partnership is
      engaged in a United States trade or business; or
 
    - some U.S. branches of foreign banks or insurance companies.
 
    Effective after 2000, backup withholding may apply to the payment of
disposition proceeds by or through a foreign office or a broker that is a United
States person or a United States related person unless specific certification
requirements are satisfied or an exemption is otherwise established and the
broker has no actual knowledge that the holder is a United States person.
Non-U.S. Holders should consult their own tax advisors regarding the application
of the information reporting and backup withholding rules to them, including
changes to these rules that will become effective after 2000.
 
    Any amounts withheld under the backup withholding rules from a payment to a
Non-U.S. Holder will be refunded, or credited against the holder's United States
federal income tax liability, if any, provided that the required information is
furnished to the United States Internal Revenue Service.
 
                                       72

<PAGE>

                                  UNDERWRITING
 
    The underwriters named below, acting through their representatives,
Robertson Stephens, Inc. and U.S. Bancorp Piper Jaffray Inc., have severally
agreed with us, subject to the terms and conditions of the underwriting
agreement, to purchase from us the number of shares of common stock set forth
opposite their respective names below. The underwriters are committed to
purchase and pay for all of these shares if any are purchased.
 

<TABLE>
<CAPTION>
                                                              NUMBERS OF
UNDERWRITER                                                     SHARES
-----------                                                   ----------
<S>                                                           <C>
Robertson Stephens, Inc.....................................
U.S. Bancorp Piper Jaffray Inc..............................
</TABLE>

 

<TABLE>
<CAPTION>
INTERNATIONAL UNDERWRITER
-------------------------
<S>                                                           <C>
Robertson Stephens International, Ltd.......................
U.S. Bancorp Piper Jaffray Inc..............................
                                                               ------
  Total.....................................................
                                                               ======
</TABLE>

 
    The representatives of the underwriters have advised us that the
underwriters propose to offer the shares of common stock to the public at the
public offering price shown on the cover page of this prospectus and to certain
dealers at that price less a concession of not more than $      per share, of
which $      may be reallowed to other dealers. After the completion of this
offering, the public offering price, concession and reallowance to dealers may
be reduced by the representatives. No such reduction will change the amount of
proceeds we are to receive as set forth on the cover page of this prospectus.
The common stock is offered by the underwriters as stated in this prospectus,
subject to receipt and acceptance by them and subject to their right to reject
any order in whole or in part.
 
    OVERALLOTMENT OPTION.  We have granted to the underwriters an option,
exercisable during the 30 day period after the date of this prospectus, to
purchase up to             additional shares of common stock at the same price
per share as we will receive for the             shares that the underwriters
have agreed to purchase. To the extent that the underwriters exercise this
option, each of the underwriters will have a firm commitment, subject to certain
conditions, to purchase approximately the same percentage of these additional
shares that the number of shares of common stock to be purchased by it shown in
the above table bears to the total number of shares offered by this prospectus.
If purchased, the additional shares will be sold by the underwriters on the same
terms as those on which the             shares are being sold. The underwriters
may exercise this option only to cover overallotments made in connection with
the sale of the shares of common stock in this offering.
 
    The following table shows the per share and total underwriting discounts and
commissions that we are to pay to the underwriters. This information is
presented assuming either no exercise or full exercise by the underwriters of
their overallotment option.
 

<TABLE>
<CAPTION>
                                                                        TOTAL
                                                               ------------------------
                                                               WITHOUT OVER   WITH OVER
                                                   PER SHARE    ALLOTMENT     ALLOTMENT
                                                   ---------   ------------   ---------
<S>                                                <C>         <C>            <C>
Price offering price.............................   $             $            $
Underwriting discounts and commissions...........   $             $            $
Proceeds, before expenses, to us.................   $             $            $
</TABLE>

 
                                       73

<PAGE>
    EXPENSES OF THIS OFFERING.  The expenses of this offering, other than the
underwriting discounts and commissions, are estimated at approximately
$      and are payable entirely by us.
 
    INDEMNITY.  The underwriting agreement contains covenants of indemnity among
the underwriters and us against civil liabilities, including liabilities under
the Securities Act and liabilities arising from breaches of representations and
warranties contained in the underwriting agreement. In addition, the
underwriting agreement contains a covenant that we will maintain Directors and
Officers liability insurance in the minimum amount of $10 million and cause
Robertson Stephens, Inc., on behalf of the underwriters, to be added to such
policy such that up to $500,000 of certain of its expenses shall be paid
directly by such insurers.
 
    LOCKUP AGREEMENTS.  Each of our executive officers, directors, and
substantially all of our other stockholders and warrantholders have agreed,
subject to limited exceptions, not to offer, sell, contract to sell, or
otherwise sell, dispose of, loan, pledge or grant any rights with respect to any
shares of common stock, any options or warrants to purchase any shares of common
stock, or any securities convertible into or exchangeable for common stock owned
by the holder as of the date of this prospectus or acquired directly from us or
with respect to which these holders have or may acquire the power of
disposition, without the prior written consent of Robertson Stephens, Inc. This
restriction terminates after the close of trading of the shares on the 180th day
after, and including, the day the shares began trading on the Nasdaq National
Market. However, Robertson Stephens, Inc. may, in its sole discretion and at any
time without notice, release all or any portion of the securities subject to
lockup agreements. There are no existing agreements between the representatives
and any of our stockholders and warrantholders who have executed a lockup
agreement providing consent to the sale of shares prior to the expiration of the
lockup period.
 
    FUTURE SALES BY US.  In addition, we have agreed that for a period of
180 days after the date of this prospectus, we will not, without the prior
written consent of Robertson Stephens, Inc. (a) consent to the disposition of
any shares held by stockholders, warrantholders or optionholders before the
expiration of the 180 day lockup period or (b) issue, sell, contract to sell or
otherwise dispose of any shares of common stock, any options or warrants to
purchase any shares of common stock or any securities convertible into,
exercisable for or exchangeable for shares of common stock, other than our sale
of shares in this offering, the issuance of shares of common stock upon the
exercise of options outstanding on the date of this prospectus and the grant of
options to purchase shares of common stock under existing employee stock option
or stock purchase plans provided that those options are subject to a 180 day
lockup.
 
    DIRECTED SHARES.  At our request, the underwriters will reserve up to 5% of
the shares of common stock for sale in this offering, at the initial public
offering price, to our customers, partners and business associates. The number
of shares of common stock available for sale to the general public will be
reduced to the extent that these individuals purchase all or a portion of the
reserved shares. Any reserved shares that are not purchased will be offered by
the underwriters to the general public on the same basis as the other shares of
common stock offered by this prospectus. We have agreed to indemnify the
underwriters of the directed share program against liabilities and expenses,
including liabilities under the Securities Act, in connection with the sale of
the reserved shares.
 
    LISTING.  We have applied for approval for quotation of our common stock on
the Nasdaq National Market under the symbol "ACAD."
 
    NO PRIOR PUBLIC MARKET.  Prior to this offering, there has been no public
market for our common stock. Consequently, the initial public offering price for
our common stock will be determined through negotiations between us and the
representatives. Among the factors to be considered in these negotiations are
prevailing market and economic conditions, our financial information, market
valuations of other companies that we and the representatives believe to be
comparable to us, estimates
 
                                       74

<PAGE>
of our business potential and the present state of our development. The
estimated initial public offering price range set forth on the cover page of
this prospectus is subject to change as a result of market conditions and other
factors. A pricing committee of our board of directors will establish the
initial public offering price following such negotiations.
 
    The underwriters have advised us that they do not expect sales to
discretionary accounts to exceed 5% of the total number of shares offered.
 
    SYNDICATE SHORT SALES.  The representatives have advised us that, on behalf
of the underwriters, they may make short sales of our common stock in connection
with this offering, resulting in the sale by the underwriters of a greater
number of shares than they are required to purchase pursuant to the underwriting
agreement. The short position resulting from those short sales will be deemed a
"covered" short position to the extent that it does not exceed the
shares subject to the underwriters' overallotment option and will be deemed a
"naked" short position to the extent that it exceeds that number. A naked short
position is more likely to be created if the underwriters are concerned that
there may be downward pressure on the trading price of the common stock in the
open market that could adversely affect investors who purchased shares in the
offering. The underwriters may reduce or close out their covered short position
either by exercising the overallotment option or by purchasing shares in the
open market. In determining which of these alternatives to pursue, the
underwriters will consider the price at which shares are available for purchase
in the open market as compared to the price at which they may purchase shares
through the overallotment option. Any naked short position will be closed out by
purchasing shares in the open market. Similar to the other stabilizing
transactions described below, open market purchases made by the underwriters to
cover all or a portion of their short position may have the effect of preventing
or retarding a decline in the market price of our common stock following this
offering. As a result, our common stock may trade at a price that is higher than
the price that otherwise might prevail in the open market.
 
    STABILIZATION.  The underwriters' representatives have advised us that,
pursuant to Regulation M under the Securities Exchange Act of 1934, as amended,
certain persons participating in this offering may engage in transactions,
including stabilizing bids, syndicate covering transactions or the imposition of
penalty bids, that may have the effect of stabilizing or maintaining the market
price of the common stock at a level above that which might otherwise prevail in
the open market. A "stabilizing bid" is a bid for or the purchase of shares of
common stock on behalf of the underwriters for the purpose of fixing or
maintaining the price of the common stock. A "syndicate covering transaction" is
the bid for or the purchase of the common stock on behalf of the underwriters to
reduce a short position incurred by the underwriters in connection with this
offering. A "penalty bid" is an arrangement permitting the underwriters'
representatives to reclaim the selling concession otherwise accruing to an
underwriter or syndicate member in connection with the offering if the common
stock originally sold by such underwriter or syndicate member is purchased by
underwriters' representatives in the open market pursuant to a stabilizing bid
or to cover all or part of a syndicate short position. The underwriters'
representatives have advised us that such transactions may be effected on the
Nasdaq National Market or otherwise and, if commenced, may be discontinued at
any time.
 
                                       75

<PAGE>

                                 LEGAL MATTERS
 
    Cooley Godward LLP, San Diego, California, will pass upon the validity of
the common stock offered by this prospectus for us. Brobeck, Phleger & Harrison
LLP, San Diego, California, will pass upon legal matters for the underwriters.
 

                                    EXPERTS
 
    The financial statements at December 31, 1998 and 1999 and for each of the
three years in the period ended December 31, 1999 included in this prospectus
have been so included in reliance on the report of PricewaterhouseCoopers LLP,
independent accountants, given on the authority of said firm as experts in
auditing and accounting.
 
                      WHERE YOU CAN FIND MORE INFORMATION
 
    We have filed with the SEC a registration statement on Form S-1 under the
Securities Act with respect to the common stock offered hereby. This prospectus,
which constitutes a part of the registration statement, does not contain all of
the information set forth in the registration statement or the exhibits and
schedules which are part of the registration statement. For further information
with respect to us and our common stock offered by this prospectus, we refer you
to the registration statement and the exhibits and schedules filed as part of
the registration statement. You may read and copy any document we file at the
SEC's public reference room at 450 Fifth Street, N.W., Washington, D.C. 20549.
Please call the SEC at 1-800-SEC-0330 for further information on the public
reference rooms. Our SEC filings are also available to the public from the SEC's
website at http://www.sec.gov.
 
    Upon completion of this offering, we will become subject to the information
and periodic reporting requirements of the Securities Exchange Act, and, in
accordance therewith, will file periodic reports, proxy statements and other
information with the SEC. These periodic reports, proxy statements and other
information will be available for inspection and copying at the SEC's public
reference rooms and the website of the SEC referred to above.
 
                                       76

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
                   INDEX TO CONSOLIDATED FINANCIAL STATEMENTS
 

<TABLE>
<CAPTION>
                                                                PAGE
                                                              --------
<S>                                                           <C>
Report of Independent Accountants...........................    F-2
 
Consolidated Balance Sheet..................................    F-3
 
Consolidated Statement of Operations........................    F-4
 
Consolidated Statement of Convertible Preferred Stock and
  Stockholders' Equity (Deficit) and Comprehensive Loss.....    F-5
 
Consolidated Statement of Cash Flows........................    F-6
 
Notes to Consolidated Financial Statements..................    F-7

</TABLE>

 
                                      F-1

<PAGE>

                       REPORT OF INDEPENDENT ACCOUNTANTS
 
To the Board of Directors and Stockholders
  of ACADIA Pharmaceuticals Inc.
 
    In our opinion, the accompanying consolidated balance sheet and the related
consolidated statements of operations, of convertible preferred stock and
stockholders' equity (deficit) and comprehensive loss and of cash flows present
fairly, in all material respects, the financial position of ACADIA
Pharmaceuticals Inc. and its subsidiary at December 31, 1998 and 1999, and the
results of their operations and their cash flows for each of the three years in
the period ended December 31, 1999, in conformity with accounting principles
generally accepted in the United States of America. These financial statements
are the responsibility of the Company's management; our responsibility is to
express an opinion on these financial statements based on our audits. We
conducted our audits of these statements in accordance with auditing standards
generally accepted in the United States of America, which require that we plan
and perform the audit to obtain reasonable assurance about whether the financial
statements are free of material misstatement. An audit includes examining, on a
test basis, evidence supporting the amounts and disclosures in the financial
statements, assessing the accounting principles used and significant estimates
made by management, and evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for our opinion.
 
PricewaterhouseCoopers LLP
 
San Diego, California
February 28, 2000

 
                                      F-2

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
                           CONSOLIDATED BALANCE SHEET
 

<TABLE>
<CAPTION>
                                                                                                      PRO FORMA
                                                                                                    STOCKHOLDERS'
                                                             DECEMBER 31,                             EQUITY AT
                                                      ---------------------------   SEPTEMBER 30,   SEPTEMBER 30,
                                                          1998           1999           2000            2000
                                                      ------------   ------------   -------------   -------------
                                                                                     (UNAUDITED)     (UNAUDITED)
<S>                                                   <C>            <C>            <C>             <C>
                                                     ASSETS
 
Cash and cash equivalents...........................  $  4,778,700   $  3,684,100   $ 10,217,900
Investment securities, available-for-sale...........    12,798,000      8,524,600     19,265,800
Accounts receivable.................................       208,800
Prepaid expenses and other current assets...........       599,700        438,300        632,900
                                                      ------------   ------------   ------------
    Total current assets............................    18,385,200     12,647,000     30,116,600
Property and equipment, net.........................     2,299,700      2,508,500      2,880,100
Other assets........................................       378,300        362,300        474,700
                                                      ------------   ------------   ------------
                                                      $ 21,063,200   $ 15,517,800   $ 33,471,400
                                                      ============   ============   ============
 
                                    LIABILITIES, CONVERTIBLE PREFERRED STOCK
                                       AND STOCKHOLDERS' EQUITY (DEFICIT)
 
Accounts payable....................................  $    278,800   $    236,700   $    379,200
Accrued expenses....................................       759,200        703,500      1,260,300
Deferred revenue....................................       310,000        291,700
Current portion of long-term debt...................        98,000        626,700      1,328,500
                                                      ------------   ------------   ------------
    Total current liabilities.......................     1,446,000      1,858,600      2,968,000
                                                      ------------   ------------   ------------
Long-term debt, less current portion................     3,366,500      4,431,700      4,631,800
                                                      ------------   ------------   ------------
Commitments (Note 10)
 
Convertible preferred stock, $0.01 par value;
  10,019,067 shares authorized; 5,692,585, 5,692,585
  and 8,625,920 shares issued and outstanding at
  December 31, 1998, 1999, and September 30, 2000,
  respectively; 5,000,000 shares authorized, no
  shares issued and outstanding pro forma;
  liquidation preference $55,761,900 at
  September 30, 2000................................    24,664,800     24,664,800     46,501,800
                                                      ------------   ------------   ------------    ------------
Stockholders' equity (deficit)
  Common stock, $0.0001 par value; 14,218,712 shares
    authorized; 2,068,248, 2,102,955 and 2,145,962
    shares issued and outstanding at December 31,
    1998, 1999 and September 30, 2000, respectively;
    50,000,000 shares authorized; 10,771,882 shares
    issued and outstanding pro forma................           200            200            200           1,100
  Additional paid-in capital........................     1,203,100      1,682,300      4,792,100      51,293,000
  Accumulated deficit...............................    (9,360,200)   (16,805,500)   (24,559,200)    (24,559,200)
  Unearned stock-based compensation.................                     (371,700)    (1,259,800)     (1,259,800)
  Unrealized loss on investment securities..........       (43,700)       (20,800)       (78,000)        (78,000)
  Cumulative translation adjustment.................      (213,500)        78,200        474,500         474,500
                                                      ------------   ------------   ------------    ------------
    Total stockholders' equity (deficit)............    (8,414,100)   (15,437,300)   (20,630,200)   $ 25,871,600
                                                      ------------   ------------   ------------    ============
                                                      $ 21,063,200   $ 15,517,800   $ 33,471,400
                                                      ============   ============   ============
</TABLE>

 
   The accompanying notes are an integral part of these financial statements.
 
                                      F-3

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
                      CONSOLIDATED STATEMENT OF OPERATIONS
 

<TABLE>
<CAPTION>
                                                                                   NINE MONTHS ENDED
                                             YEAR ENDED DECEMBER 31,                 SEPTEMBER 30,
                                     ---------------------------------------   -------------------------
                                        1997          1998          1999          1999          2000
                                     -----------   -----------   -----------   -----------   -----------
                                                                               (UNAUDITED)   (UNAUDITED)
<S>                                  <C>           <C>           <C>           <C>           <C>
Revenues
  Collaborative revenues--related
    party..........................  $   273,500   $ 1,300,000   $ 2,238,200   $ 1,334,400   $ 2,648,600
  Other research revenues..........      561,800       119,400                                   119,400
                                     -----------   -----------   -----------   -----------   -----------
    Total revenues.................      835,300     1,419,400     2,238,200     1,334,400     2,768,000
                                     -----------   -----------   -----------   -----------   -----------
Operating expenses
  Research and development
    (including stock-based
    compensation of $3,300,
    $99,700, $37,800 and $353,000
    for the years ended
    December 31, 1998 and 1999 and
    for the nine months ended
    September 30, 1999 and 2000,
    respectively)..................    2,295,300     5,855,900     7,625,700     5,582,100     7,253,100
  General and administrative
    (including stock-based
    compensation of $49,400,
    $5,800, $4,900 and $1,855,900
    for the years ended
    December 31, 1998 and 1999 and
    for the nine months ended
    September 30, 1999 and 2000,
    respectively)..................    1,770,800     2,487,000     2,457,600     1,996,400     3,989,200
                                     -----------   -----------   -----------   -----------   -----------
    Total operating expenses.......    4,066,100     8,342,900    10,083,300     7,578,500    11,242,300
                                     -----------   -----------   -----------   -----------   -----------
Loss from operations...............   (3,230,800)   (6,923,500)   (7,845,100)   (6,244,100)   (8,474,300)
Interest income....................      283,200       689,000       751,000       575,700     1,013,100
Interest expense...................      (34,300)     (168,000)     (351,200)     (237,900)     (292,500)
                                     -----------   -----------   -----------   -----------   -----------
Net loss...........................  $(2,981,900)  $(6,402,500)  $(7,445,300)  $(5,906,300)  $(7,753,700)
                                     ===========   ===========   ===========   ===========   ===========
Net loss per share, basic and
  diluted..........................  $     (1.74)  $     (3.12)  $     (3.57)  $     (2.83)  $     (3.63)
                                     ===========   ===========   ===========   ===========   ===========
Weighted average shares
  outstanding, basic and diluted...    1,712,055     2,049,307     2,086,977     2,083,369     2,134,084
                                     ===========   ===========   ===========   ===========   ===========
Pro forma net loss per share, basic
  and diluted (unaudited)..........                              $     (0.96)                $     (0.83)
                                                                 ===========                 ===========
Pro forma weighted average shares
  outstanding, basic and diluted
  (unaudited)......................                                7,779,562                   9,360,004
                                                                 ===========                 ===========
</TABLE>

 
   The accompanying notes are an integral part of these financial statements.
 
                                      F-4

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
           CONSOLIDATED STATEMENT OF CONVERTIBLE PREFERRED STOCK AND
             STOCKHOLDERS' EQUITY (DEFICIT) AND COMPREHENSIVE LOSS

<TABLE>
<CAPTION>
                                           CONVERTIBLE
                                         PREFERRED STOCK           COMMON STOCK       ADDITIONAL                    UNEARNED
                                     -----------------------   --------------------    PAID-IN     ACCUMULATED    STOCK-BASED
                                      SHARES       AMOUNT       SHARES      AMOUNT     CAPITAL       DEFICIT      COMPENSATION
                                     ---------   -----------   ---------   --------   ----------   ------------   ------------
<S>                                  <C>         <C>           <C>         <C>        <C>          <C>            <C>
Balances at December 31, 1996......                            1,523,088     $200     $      100   $   (244,300)
  Issuance of Series A preferred
    stock at $2.55 per share, net
    of issuance costs..............  2,372,548   $ 5,611,000
  Elimination of S Corporation
    deficit against additional paid
    in capital upon issuance of
    Series A preferred stock.......                                                     (268,500)       268,500
  Issuance of Series B preferred
    stock at $4.00 per share, net
    of issuance costs..............    738,384     2,914,800
  Issuance of Series C preferred
    stock at $6.00 per share, net
    of issuance costs..............  1,000,000     5,986,300
  Issuance of common stock from
    exercise of stock options......                              223,370                   2,300
  Issuance of common stock from
    exercise of $6.00 stock
    warrants.......................                              237,257               1,415,600
  Net loss.........................                                                                  (2,981,900)
  Cumulative translation
    adjustment.....................
                                     ---------   -----------   ---------     ----     ----------   ------------   -----------
Balances at December 31, 1997......  4,110,932    14,512,100   1,983,715      200      1,149,500     (2,957,700)           --
  Issuance of Series D preferred
    stock at $6.75 per share, net
    of issuance costs..............  1,581,653    10,152,700
  Issuance of common stock from
    exercise of stock options......                               84,533                     900
  Net loss.........................                                                                  (6,402,500)
  Noncash compensation related to
    stock options granted..........                                                       52,700
  Unrealized loss on investment
    securities.....................
  Cumulative translation
    adjustment.....................
                                     ---------   -----------   ---------     ----     ----------   ------------   -----------
Balances at December 31, 1998......  5,692,585    24,664,800   2,068,248      200      1,203,100     (9,360,200)           --
  Issuance of common stock from
    exercise of stock options......                               34,707                   2,000
  Net loss.........................                                                                  (7,445,300)
  Noncash compensation related to
    stock options granted..........                                                      477,200                  $  (371,700)
  Unrealized gain on investment
    securities.....................
  Cumulative translation
    adjustment.....................
                                     ---------   -----------   ---------     ----     ----------   ------------   -----------
Balances at December 31, 1999......  5,692,585    24,664,800   2,102,955      200      1,682,300    (16,805,500)     (371,700)
  Issuance of Series E preferred
    stock at $7.50 per share, net
    of issuance costs..............  2,933,335    21,837,000
  Issuance of common stock from
    exercise of stock options......                               43,007                  12,800
  Net loss.........................                                                                  (7,753,700)
  Noncash compensation related to
    stock options granted..........                                                    3,097,000                     (888,100)
  Unrealized loss on investment
    securities.....................
  Cumulative translation
    adjustment.....................
                                     ---------   -----------   ---------     ----     ----------   ------------   -----------
Balances at September 30, 2000
  (unaudited)......................  8,625,920   $46,501,800   2,145,962     $200     $4,792,100   $(24,559,200)  $(1,259,800)
                                     =========   ===========   =========     ====     ==========   ============   ===========
 
<CAPTION>
                                     UNREALIZED                     TOTAL
                                      LOSS ON     CUMULATIVE    STOCKHOLDERS'
                                     INVESTMENT   TRANSLATION      EQUITY       COMPREHENSIVE
                                     SECURITIES   ADJUSTMENT      (DEFICIT)         LOSS
                                     ----------   -----------   -------------   -------------
<S>                                  <C>          <C>           <C>             <C>
Balances at December 31, 1996......                             $   (244,000)    $  (192,500)
                                                                                 ===========
  Issuance of Series A preferred
    stock at $2.55 per share, net
    of issuance costs..............                                       --
  Elimination of S Corporation
    deficit against additional paid
    in capital upon issuance of
    Series A preferred stock.......                                       --
  Issuance of Series B preferred
    stock at $4.00 per share, net
    of issuance costs..............                                       --
  Issuance of Series C preferred
    stock at $6.00 per share, net
    of issuance costs..............                                       --
  Issuance of common stock from
    exercise of stock options......                                    2,300
  Issuance of common stock from
    exercise of $6.00 stock
    warrants.......................                                1,415,600
  Net loss.........................                               (2,981,900)    $(2,981,900)
  Cumulative translation
    adjustment.....................                $(181,500)       (181,500)       (181,500)
                                      --------     ---------    ------------     -----------
Balances at December 31, 1997......         --      (181,500)     (1,989,500)    $(3,163,400)
                                                                                 ===========
  Issuance of Series D preferred
    stock at $6.75 per share, net
    of issuance costs..............                                       --
  Issuance of common stock from
    exercise of stock options......                                      900
  Net loss.........................                               (6,402,500)    $(6,402,500)
  Noncash compensation related to
    stock options granted..........                                   52,700
  Unrealized loss on investment
    securities.....................   $(43,700)                      (43,700)        (43,700)
  Cumulative translation
    adjustment.....................                  (32,000)        (32,000)        (32,000)
                                      --------     ---------    ------------     -----------
Balances at December 31, 1998......    (43,700)     (213,500)     (8,414,100)    $(6,478,200)
                                                                                 ===========
  Issuance of common stock from
    exercise of stock options......                                    2,000
  Net loss.........................                               (7,445,300)    $(7,445,300)
  Noncash compensation related to
    stock options granted..........                                  105,500
  Unrealized gain on investment
    securities.....................     22,900                        22,900          22,900
  Cumulative translation
    adjustment.....................                  291,700         291,700         291,700
                                      --------     ---------    ------------     -----------
Balances at December 31, 1999......    (20,800)       78,200     (15,437,300)    $(7,130,700)
                                                                                 ===========
  Issuance of Series E preferred
    stock at $7.50 per share, net
    of issuance costs..............                                       --
  Issuance of common stock from
    exercise of stock options......                                   12,800
  Net loss.........................                               (7,753,700)    $(7,753,700)
  Noncash compensation related to
    stock options granted..........                                2,208,900
  Unrealized loss on investment
    securities.....................    (57,200)                      (57,200)        (57,200)
  Cumulative translation
    adjustment.....................                  396,300         396,300         396,300
                                      --------     ---------    ------------     -----------
Balances at September 30, 2000
  (unaudited)......................   $(78,000)    $ 474,500    $(20,630,200)    $(7,414,600)
                                      ========     =========    ============     ===========
</TABLE>

 
   The accompanying notes are an integral part of these financial statements.
 
                                      F-5

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
                      CONSOLIDATED STATEMENT OF CASH FLOWS
 

<TABLE>
<CAPTION>
                                                                                       NINE MONTHS ENDED
                                                YEAR ENDED DECEMBER 31,                  SEPTEMBER 30,
                                        ----------------------------------------   --------------------------
                                           1997           1998          1999          1999           2000
                                        -----------   ------------   -----------   -----------   ------------
<S>                                     <C>           <C>            <C>           <C>           <C>
CASH FLOWS FROM OPERATING ACTIVITIES
  Net loss............................  $(2,981,900)  $ (6,402,500)  $(7,445,300)  $(5,906,300)  $ (7,753,700)
  Adjustments to reconcile net loss to
    cash used in operating activities:
    Depreciation and amortization.....      158,200        509,800       790,800       577,000        731,400
    Stock-based compensation..........                      52,700       105,500        42,700      2,208,900
    Changes in operating assets and
      liabilities:
      Accounts receivable.............     (248,200)        87,500       208,800       208,800
      Prepaid expenses and other
        current assets................      (48,600)      (534,900)      140,700       164,000       (328,700)
      Other assets....................     (306,300)       (16,700)        5,000
      Accounts payable................      441,900       (215,000)      (21,100)      (19,000)       150,500
      Accrued expenses................      121,200        459,900       251,800       179,200        821,800
      Deferred revenue................       81,600         75,000       (18,300)      106,700       (291,700)
                                        -----------   ------------   -----------   -----------   ------------
      Net cash used in operating
        activities....................   (2,782,100)    (5,984,200)   (5,982,100)   (4,646,900)    (4,461,500)
                                        -----------   ------------   -----------   -----------   ------------
CASH FLOWS FROM INVESTING ACTIVITIES
  Purchases of investment
    securities........................                 (17,356,700)   (3,586,700)   (2,125,900)   (17,343,500)
  Maturities of investment
    securities........................                   4,515,000     7,883,000     6,700,000      6,545,000
  Purchases of property and
    equipment.........................   (1,646,100)    (1,174,400)   (1,142,500)     (904,300)    (1,241,100)
                                        -----------   ------------   -----------   -----------   ------------
      Net cash (used in) provided by
        investing activities..........   (1,646,100)   (14,016,100)    3,153,800     3,669,800    (12,039,600)
                                        -----------   ------------   -----------   -----------   ------------
CASH FLOWS FROM FINANCING ACTIVITIES
  Proceeds from issuance of long-term
    debt..............................    1,203,300      2,140,400     1,987,800     1,133,400      1,719,000
  Repayments of long-term debt........     (100,400)                    (156,000)     (106,900)      (431,900)
  Proceeds from issuance of preferred
    stock, net of issuance costs......   14,512,100     10,152,700                                 21,837,000
  Proceeds from issuance of common
    stock.............................    1,417,900            900         2,000           200         12,800
                                        -----------   ------------   -----------   -----------   ------------
      Net cash provided by financing
        activities....................   17,032,900     12,294,000     1,833,800     1,026,700     23,136,900
                                        -----------   ------------   -----------   -----------   ------------
Effect of exchange rate changes on
  cash................................     (192,500)        67,400      (100,100)      (48,500)      (102,000)
                                        -----------   ------------   -----------   -----------   ------------
Net increase (decrease) in cash and
  cash equivalents....................   12,412,200     (7,638,900)   (1,094,600)        1,100      6,533,800
Cash and cash equivalents, beginning
  of period...........................        5,400     12,417,600     4,778,700     4,778,700      3,684,100
                                        -----------   ------------   -----------   -----------   ------------
Cash and cash equivalents, end of
  period..............................  $12,417,600   $  4,778,700   $ 3,684,100   $ 4,779,800   $ 10,217,900
                                        ===========   ============   ===========   ===========   ============
SUPPLEMENTAL DISCLOSURE OF CASH FLOW
  INFORMATION
  Interest paid.......................  $     4,300   $      4,000   $    82,200   $    56,000   $    482,400
SUPPLEMENTAL SCHEDULE OF NONCASH
  INVESTING AND FINANCING ACTIVITIES
  Unrealized gain (loss) on investment
    securities........................  $        --   $    (43,700)  $    22,900   $    23,400   $    (57,200)
</TABLE>

 
   The accompanying notes are an integral part of these financial statements.
 
                                      F-6

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
 
1. ORGANIZATION AND NATURE OF OPERATIONS
 
    ACADIA Pharmaceuticals Inc. (the "Company"), a Delaware corporation, was
incorporated on July 16, 1993, and is a genomics-based drug discovery and
development company that efficiently identifies target-specific small molecule
drug candidates using its integrated technology platform. The Company's
proprietary approach integrates genomics, chemistry and biology to rapidly
indentify and validate targets and discover chemistries specific to those
targets. The Company has successfully applied its approach to generate a drug
discovery pipeline that currently includes six advanced programs as well as a
number of earlier stage research projects. ACADIA Pharmaceuticals A/S, a wholly
owned subsidiary of the Company based near Copenhagen, Denmark, was established
in 1997 to conduct the Company's chemistry research operations.
 
    The Company has not been profitable and has generated substantial operating
losses since incorporating in 1993. At September 30, 2000, the Company's
accumulated losses were approximately $24.6 million. The Company expects to
increase operating expenses over the next several years as it expands its
research and development activities and enhances its core technologies.
Accordingly, the Company will require significant additional financing in the
future to fund operations. The Company does not know whether additional
financing will be available when needed, or that, if available, it will obtain
financing on favorable terms. If adequate funds are not available or are not
available on acceptable terms, the Company's ability to fund its operations,
take advantage of opportunities, develop drug candidates and technologies or
otherwise respond to competitive pressures could be significantly limited.
 
2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
 
    Significant accounting policies followed in the preparation of these
financial statements are as follows:
 
PRINCIPLES OF CONSOLIDATION
 
    The accompanying consolidated financial statements include the accounts of
the Company and ACADIA Pharmaceuticals A/S, its wholly owned subsidiary. All
intercompany accounts and transactions have been eliminated in consolidation.
 
UNAUDITED INTERIM FINANCIAL INFORMATION
 
    The consolidated balance sheet at September 30, 2000, the consolidated
statements of operations and cash flows for the nine months ended September 30,
1999 and 2000, and the consolidated statement of convertible preferred stock and
stockholders' equity (deficit) and comprehensive loss for the nine months ended
September 30, 2000, are unaudited. The unaudited consolidated financial
statements have been prepared on the same basis as the audited consolidated
financial statements and, in the opinion of management, include all adjustments,
consisting only of normal recurring adjustments, necessary to state fairly the
financial information set forth therein, in accordance with accounting
principles generally accepted in the United States of America.
 
UNAUDITED PRO FORMA STOCKHOLDERS' EQUITY
 
    The Company's Board of Directors has authorized the filing of a registration
statement with the Securities and Exchange Commission to register shares of its
common stock in an initial public offering ("IPO"). If the IPO is closed under
certain terms, each share of preferred stock outstanding will
 
                                      F-7

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
convert into one share of common stock. Unaudited pro forma stockholders' equity
at September 30, 2000 reflects the conversion of all outstanding preferred stock
into common stock as if such conversion had occurred at September 30, 2000.
 
CASH AND CASH EQUIVALENTS
 
    The Company considers all highly liquid investments with an initial maturity
date at the date of purchase of three months or less to be cash equivalents. The
carrying amount of cash and cash equivalents approximates fair value.
 
INVESTMENT SECURITIES
 
    Investment securities are considered to be available-for-sale and are
carried at fair value. Unrealized gains and losses, if any, are reported in a
separate component of stockholders' equity (deficit). The cost of investment
securities classified as available-for-sale is adjusted for amortization of
premiums and accretion of discounts to maturity. Such amortization and accretion
are included in interest income. Realized gains and losses are also included in
interest income. The cost of securities sold is based on the specific
identification method.
 
PROPERTY AND EQUIPMENT
 
    Property and equipment are recorded at cost and depreciated over their
estimated useful lives (generally three to seven years) using the straight line
method. Leasehold improvements are amortized over the shorter of their estimated
useful lives or the term of the respective leases by use of the straight line
method. Maintenance and repair costs are expensed as incurred. When assets are
retired or sold, the assets and accumulated depreciation are removed from the
respective accounts and any gain or loss is recognized.
 
REVENUES
 
    Revenues under collaborative agreements are recognized as research
activities are performed over the term of the agreements. Upfront license and
milestone payments received that are related to future performance under such
agreements are deferred and recognized as revenue when earned over the term of
the agreement.
 
RESEARCH AND DEVELOPMENT COSTS
 
    Research and development costs are expensed as incurred.
 
CONCENTRATIONS OF RISK
 
    Financial instruments which potentially subject the Company to
concentrations of credit risk principally consist of cash, cash equivalents and
investment securities. The Company invests its excess cash primarily in
marketable debt securities of corporations and financial institutions with
strong credit ratings. The Company has established guidelines relative to
diversification and maturities to maintain safety and liquidity.
 
    During the nine months ended September 30, 2000, revenues from one party
accounted for approximately 96% of total revenues.
 
                                      F-8

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
FOREIGN CURRENCY TRANSLATION
 
    The functional currency of ACADIA Pharmaceuticals A/S is the local currency.
Accordingly, all assets and liabilities of this entity are translated at the
current exchange rate at the balance sheet date. Revenue and expense components
are translated at weighted average exchange rates in effect during the period.
Gains and losses resulting from foreign currency translation are included as a
component of stockholders' equity (deficit).
 
STOCK-BASED COMPENSATION
 
    The Company measures compensation expense for its employee stock-based
compensation plan using the intrinsic value method and provides pro forma
disclosures of net income (loss) as if a fair value method had been applied in
measuring compensation expense. Accordingly, compensation cost for stock awards
is measured as the excess, if any, of the fair value for financial reporting
purposes of the Company's common stock at the date of grant over the amount an
employee must pay to acquire the stock. Compensation cost is amortized over the
related vesting periods using an accelerated method in accordance with Financial
Accounting Standards Board Interpretation No. 28, ACCOUNTING FOR STOCK
APPRECIATION RIGHTS AND OTHER VARIABLE STOCK OPTION OR AWARD PLANS. Accrued
compensation costs for unvested awards that are forfeited are reversed against
compensation expense or unearned stock-based compensation, as appropriate, in
the period of forfeiture.
 
    Stock-based awards issued to nonemployees are accounted for using a fair
value method and are remeasured to fair value at each period end until the
earlier of the date that performance by the nonemployee is complete or a
performance commitment has been obtained.
 
INCOME TAXES
 
    Current income tax expense or benefit represents the amount of income taxes
expected to be payable or refundable for the current year. A deferred income tax
asset or liability is computed for the expected future impact of differences
between the financial reporting and income tax bases of assets and liabilities
and for the expected future tax benefit to be derived from tax credits and loss
carryforwards. Deferred income tax expense or benefit represents the net change
during the year in the deferred income tax asset or liability. Deferred tax
assets are reduced by a valuation allowance when, in the opinion of management,
it is more likely than not that some portion or all of the deferred tax assets
will not be realized.
 
USE OF ESTIMATES
 
    The preparation of financial statements in conformity with accounting
principles generally accepted in the United States of America requires
management to make estimates and assumptions that affect the reported amounts of
assets and liabilities, the disclosure of contingent assets and liabilities at
the date of the financial statements and the reported amounts of revenues and
expenses during the reporting period. Actual results could differ from these
estimates.
 
LONG LIVED ASSETS
 
    The Company assesses potential impairments to its long lived assets when
there is evidence that events or changes in circumstances indicate that the
carrying amount of an asset may not be
 
                                      F-9

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
recoverable. An impairment loss is recognized if the sum of expected future
undiscounted cash flows before interest from the use of the asset is less than
the net book value of the asset. The amount of the impairment loss, if any, will
generally be measured as the difference between the net book value of the assets
and their estimated fair values. No such impairment losses have been recorded by
the Company.
 
COMPREHENSIVE INCOME (LOSS)
 
    All components of comprehensive income (loss), including net income (loss),
are reported in the financial statements in the period in which they are
recognized. Comprehensive income (loss) is defined as the change in equity (net
assets) of a business enterprise during a period from transactions and other
events and circumstances from nonowner sources. Accordingly, in addition to
reporting net income (loss) under the current rules, the Company is required to
display the impact of any fluctuations in its foreign currency translation
adjustments and any unrealized gains or losses on its investment securities as
components of comprehensive income (loss) and to display an amount representing
total comprehensive income (loss) for each period.
 
NET INCOME (LOSS) PER SHARE
 
    Basic earnings (loss) per share is computed by dividing income (loss)
available to common stockholders by the weighted average number of common shares
outstanding for the period. Diluted earnings (loss) per share is computed by
dividing income (loss) available to common stockholders by the weighted average
number of common shares outstanding during the period increased to include
potential dilutive common shares that were outstanding during the period. The
dilutive effect of outstanding stock options and warrants is reflected, when
dilutive, in diluted earnings (loss) per share by application of the treasury
stock method.
 
    The Company has excluded all preferred stock and outstanding stock options
and warrants from the calculation of diluted net loss per common share because
all such securities are antidilutive for all periods presented. The total number
of potential common shares excluded from the calculation of diluted net loss per
share, prior to application of the treasury stock method for options and
warrants, was 3,770,184, 5,800,478 and 7,319,611 for the years ended
December 31, 1997, 1998 and 1999, and 7,293,175 and 8,973,123 for the nine
months ended September 30, 1999 and 2000, respectively.
 
    Unaudited pro forma basic and diluted net loss per common share, presented
in the statements of operations, has been computed for the year ended
December 31, 1999 and for the nine months ended September 30, 2000 as described
above, and also gives effect to the assumed conversion of preferred stock which,
under certain circumstances, will convert to common stock immediately prior to
the completion of the offering contemplated by this prospectus (using the "as if
converted" method) from the original date of issuance. The calculation of
unaudited pro forma net loss per share for the year ended December 31, 1999 and
the nine months ended September 30, 2000 excludes 1,627,026 and 1,747,203
shares, respectively.
 
                                      F-10

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
    The following table presents the calculation of net loss per share:
 

<TABLE>
<CAPTION>
                                                                                   NINE MONTHS ENDED
                                             YEAR ENDED DECEMBER 31,                 SEPTEMBER 30,
                                     ---------------------------------------   -------------------------
                                        1997          1998          1999          1999          2000
                                     -----------   -----------   -----------   -----------   -----------
                                                                                      (UNAUDITED)
<S>                                  <C>           <C>           <C>           <C>           <C>
Net loss..........................   $(2,981,900)  $(6,402,500)  $(7,445,300)  $(5,906,300)  $(7,753,700)
                                     -----------   -----------   -----------   -----------   -----------
Basic and diluted net loss per
  share...........................   $     (1.74)  $     (3.12)  $     (3.57)  $     (2.83)  $     (3.63)
                                     -----------   -----------   -----------   -----------   -----------
Weighted average shares used in
  computing net loss per share,
  basic and diluted...............     1,712,055     2,049,307     2,086,977     2,083,369     2,134,084
Unaudited pro forma net loss per
  share, basic and diluted........                               $     (0.96)                $     (0.83)
                                                                 -----------                 -----------
Shares used to compute unaudited
  pro forma net loss per share:
  Weighted average shares used in
    computing net loss per share,
    basic and diluted.............                                 2,086,977                   2,134,084
  Unaudited pro forma adjustment
    to reflect weighted average
    effect of assumed conversion
    of preferred stock............                                 5,692,585                   7,225,920
                                                                 -----------                 -----------
  Shares used in computing
    unaudited pro forma net loss
    per share, basic and
    diluted.......................                                 7,779,562                   9,360,004
                                                                 ===========                 ===========
</TABLE>

 
SEGMENT REPORTING
 
    Statement of Financial Accounting Standards No. 131, DISCLOSURES ABOUT
SEGMENTS OF AN ENTERPRISE AND RELATED INFORMATION, requires the use of a
management approach in identifying segments of an enterprise. Management has
determined that the Company operates in one business segment.
 
RECENTLY ISSUED ACCOUNTING STANDARDS
 
    In December 1999, the Securities and Exchange Commission issued Staff
Accounting Bulletin No. 101 ("SAB 101"), REVENUE RECOGNITION IN FINANCIAL
STATEMENTS. The objective of SAB 101 is to provide further guidance on revenue
recognition issues in the absence of authoritative literature addressing a
specified arrangement or a specific industry. The Company has adopted SAB 101
for all periods presented.
 
    In June 1998, the Financial Accounting Standards Board issued Statement of
Financial Accounting Standards No. 133 ("SFAS 133") ACCOUNTING FOR DERIVATIVE
INSTRUMENTS AND HEDGING ACTIVITIES, which the Company will adopt effective
January 1, 2001. SFAS 133 establishes accounting and reporting standards for
derivative instruments, including certain derivative instruments imbedded in
other contracts (collectively referred to as derivatives), and for hedging
activities. It requires that an entity recognize all
 
                                      F-11

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
derivatives as either assets or liabilities and measure those instruments at
fair value. Management does not believe the adoption of SFAS 133 will impact the
financial statements as the Company currently does not invest in derivative
instruments or engage in hedging activities.
 
    In March 2000, the Financial Accounting Standards Board issued
Interpretation No. 44 ("FIN 44"), ACCOUNTING FOR CERTAIN TRANSACTIONS INVOLVING
STOCK COMPENSATION. The Company adopted FIN 44 effective July 1, 2000 with
respect to specific provisions applicable to new awards, exchanges of awards in
a business combination, modifications to outstanding awards and changes in
grantee status that occur on or after that date. FIN 44 addresses practice
issues related to the application of Accounting Practice Bulletin Opinion
No. 25, ACCOUNTING FOR STOCK ISSUED TO EMPLOYEES.
 
3. INVESTMENT SECURITIES
 
    Investment securities are comprised entirely of marketable debt securities
of corporations and financial institutions. The estimated fair value of
available-for-sale securities by contractual maturity is as follows:
 

<TABLE>
<CAPTION>
                                              DECEMBER 31,
                                        -------------------------   SEPTEMBER 30,
                                           1998          1999            2000
                                        -----------   -----------   --------------
                                                                     (UNAUDITED)
<S>                                     <C>           <C>           <C>
Due within one year...................  $ 7,177,200   $ 7,535,000    $15,378,200
Due after one year....................    5,620,800       989,600      3,887,600
                                        -----------   -----------    -----------
                                        $12,798,000   $ 8,524,600    $19,265,800
                                        ===========   ===========    ===========
</TABLE>

 
    The estimated fair value of investment securities at December 31, 1998 and
1999 and at September 30, 2000 was lower than historical cost and, therefore,
unrealized losses of $43,700, $20,800 and $78,000, respectively, have been
reported as separate components of stockholders' equity (deficit). The Company
had no realized gains or losses during the years ended December 31, 1997, 1998
and 1999.
 
4. BALANCE SHEET COMPONENTS
 
    Property and equipment consist of the following:
 

<TABLE>
<CAPTION>
                                                DECEMBER 31,
                                           -----------------------   SEPTEMBER 30,
                                              1998         1999          2000
                                           ----------   ----------   -------------
                                                                      (UNAUDITED)
<S>                                        <C>          <C>          <C>
Machinery and equipment..................  $1,254,300   $1,586,700    $2,091,600
Computers and software...................     791,300    1,056,400     1,277,400
Furniture and fixtures...................      90,500       95,300        94,300
Leasehold improvements...................     887,700    1,226,300     1,520,800
                                           ----------   ----------    ----------
                                            3,023,800    3,964,700     4,984,100
Accumulated depreciation and
  amortization...........................    (724,100)  (1,456,200)   (2,104,000)
                                           ----------   ----------    ----------
                                           $2,299,700   $2,508,500    $2,880,100
                                           ==========   ==========    ==========
</TABLE>

 
                                      F-12

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
4. BALANCE SHEET COMPONENTS (CONTINUED)
    Accrued expenses consist of:
 

<TABLE>
<CAPTION>
                                                DECEMBER 31,
                                           -----------------------   SEPTEMBER 30,
                                              1998         1999          2000
                                           ----------   ----------   -------------
                                                                      (UNAUDITED)
<S>                                        <C>          <C>          <C>
Accrued compensation.....................  $  502,200   $  453,300    $  979,400
Accrued professional fees................      91,300       67,200        71,300
Other....................................     165,700      183,000       209,600
                                           ----------   ----------    ----------
                                           $  759,200   $  703,500    $1,260,300
                                           ==========   ==========    ==========
</TABLE>

 
5. LONG-TERM DEBT
 
    In February 1997, the Company's Danish subsidiary was granted a loan from
The VaekstFonden (The Danish Fund for Industrial Growth, "Growth Fund"). The
loan is funded on a quarterly basis over the term of a research project
conducted by the subsidiary up to a maximum commitment of approximately
$5.3 million. The loan accrues interest at 7.7% per annum, and principal and
interest are payable in quarterly installments which are based on a percentage
of estimated project related revenues, and it is anticipated that the repayment
period will span five years. Should actual revenues fail to materialize or fall
short of projections, the terms of the agreement provide that the loan may be
forgiven or the repayment schedule revised at the discretion of the Growth Fund.
Intellectual property rights resulting from the project are pledged to the
Growth Fund but the Company may license rights to third parties, subject to
certain conditions. During the nine months ended September 30, 2000, the Company
made payments of $244,200 on the loan. At December 31, 1998 and 1999, and at
September 30, 2000, $2,806,000, $4,060,200 and $4,397,500, respectively, had
been drawn on the loan with interest accrued of $197,900, $256,000 and $345,400,
respectively.
 
    In October 1998 and September 2000, the Company entered into equipment
financing agreements which, subject to compliance with certain financial
covenants and conditions, may be used by the Company to finance up to
$1 million and $2.3 million of capital expenditures, respectively. The Company
was in compliance with these financial covenants and conditions at December 31,
1999 and September 30, 2000. The agreements provide for equal monthly
installments to be paid over a three to four year period for each draw under the
financing agreements, including interest at rates ranging from 10.59% to 12.58%
per annum. Outstanding borrowings under these agreements are collateralized by
the equipment purchased under these financing agreements. At December 31, 1998
and 1999 and at September 30, 2000, the Company had $460,600, $742,200 and
$1,217,400 in outstanding borrowings under these agreements, respectively.
 
                                      F-13

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
5. LONG-TERM DEBT (CONTINUED)
    At December 31, 1999, future payments under the Growth Fund loan and
equipment financing agreement are as follows:
 

<TABLE>
<S>                                                           <C>
YEAR ENDED DECEMBER 31,
 
  2000......................................................  $  626,700
  2001......................................................     753,900
  2002......................................................     917,400
  2003......................................................   1,075,600
  2004......................................................   1,545,800
  2005......................................................     139,000
                                                              ----------
                                                               5,058,400
  Less current portion......................................    (626,700)
                                                              ----------
    Long-term portion.......................................  $4,431,700
                                                              ==========
</TABLE>

 
6. COLLABORATIVE RESEARCH AND LICENSING AGREEMENTS
 
    In July 1999, the Company entered into a license and collaboration agreement
with Allergan, Inc. to develop and commercialize drugs for glaucoma based on
ACADIA's proprietary lead compounds. Under the agreement, the Company will
provide its expertise in medicinal chemistry and high throughput pharmacology
for a two year period to enable the selection by Allergan of up to two
development candidates for clinical development and commercialization. Allergan
was granted worldwide rights to products based on these lead compounds for the
treatment of ocular disease. In exchange, the Company is eligible to receive up
to approximately $19 million for the first development candidate, in the form of
up front fees, research support and milestone payments. The Company will also
receive royalties on future product sales, if any. Allergan also has the right
to select a second development candidate, subject to similar milestone and
royalty payments to the Company. Revenue recognized under this agreement totaled
$967,000, $404,400 and $1,617,300 during the year ended December 31, 1999 and
during the nine months ended September 30, 1999 and 2000, respectively.
 
    In September 1997, the Company established a three year collaboration
agreement with Allergan, Inc. to work jointly and exclusively on target
validation and discovery efforts on several potential drug targets. Allergan has
exclusive development and commercialization rights to all therapeutics, with the
exception that the Company retains the development rights to at least one
therapeutic indication for each target. This collaboration was extended in
September 2000 for an additional two year period. Under the collaboration, the
Company receives research funding. The Company is also eligible to receive
milestone payments of up to $12.5 million for the first product developed for
each target as well as royalties on sales of products, if any, resulting from
the collaboration. The agreement provides Allergan certain rights of negotiation
in the event of a proposed acquisition of the Company. Revenue recognized under
this agreement totaled $273,500, $1,300,000 and $1,271,200 during the years
ended December 31, 1997, 1998 and 1999, and $930,000 and $1,031,300 during the
nine months ended September 30, 1999 and 2000, respectively. In September 1997,
Allergan also made a $6 million equity investment in the Company, acquiring
1,000,000 shares of Series C preferred stock.
 
                                      F-14

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
7. CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT)
 
CONVERTIBLE PREFERRED STOCK
 
    A summary of the Company's convertible preferred stock is as follows:
 

<TABLE>
<CAPTION>
                                   SHARES AUTHORIZED                     SHARES ISSUED AND OUTSTANDING         PREFERENCE IN
                       -----------------------------------------   -----------------------------------------    LIQUIDATION
                             DECEMBER 31,                                DECEMBER 31,                               AT
                       -------------------------   SEPTEMBER 30,   -------------------------   SEPTEMBER 30,   SEPTEMBER 30,
                          1998          1999           2000           1998          1999           2000            2000
                       -----------   -----------   -------------   -----------   -----------   -------------   -------------
                                                    (UNAUDITED)                                 (UNAUDITED)     (UNAUDITED)
<S>                    <C>           <C>           <C>             <C>           <C>           <C>             <C>
Series A.............    2,372,548     2,372,548      2,372,548      2,372,548     2,372,548      2,372,548     $ 8,268,300
Series B.............      738,384       738,384        738,384        738,384       738,384        738,384       3,876,500
Series C.............    1,000,000     1,000,000      1,000,000      1,000,000     1,000,000      1,000,000       7,800,000
Series D.............    1,908,135     1,908,135      1,908,135      1,581,653     1,581,653      1,581,653      12,900,400
Series E.............                                 4,000,000                                   2,933,335      22,916,700
                       -----------   -----------    -----------    -----------   -----------    -----------     -----------
                         6,019,067     6,019,067     10,019,067      5,692,585     5,692,585      8,625,920     $55,761,900
                       ===========   ===========    ===========    ===========   ===========    ===========     ===========
</TABLE>

 
CONVERSION
 
    Each share of the Company's Series A, B, D and E preferred stock is
convertible in certain circumstances into one share of common stock upon the
closing of a qualifying initial public offering ("Qualifying IPO"). The
Company's Series C preferred stock automatically converts into one share of
common stock, subject to certain antidilution provisions, upon the closing of a
Qualifying IPO. A Qualifying IPO is defined as an initial public offering of the
Company's common stock pursuant to an effective registration statement under the
Securities Act of 1933, resulting in gross proceeds of at least $7.5 million in
the case of Series A and B shares, $15 million in the case of Series C and D
shares and $20 million in the case of Series E shares, at a price per share of
at least $7.50 in the case of Series A and B shares, $12.00 in the case of
Series C and D shares and $15.00 in the case of Series E shares. In addition,
holders of Series C preferred stock may at any time elect to convert each share
into one share of common stock, subject to certain antidilution provisions.
 
VOTING RIGHTS
 
    With the exception of certain matters, the holders of preferred stock vote
together with the holders of common stock as a single class. Holders of
preferred stock are entitled to one vote for each share of common stock into
which such shares would convert.
 
DIVIDENDS
 
    The holders of preferred stock are entitled to receive dividends when and if
the Company declares a dividend on its common stock, in such amount as they
would be entitled to receive if the preferred stock had been converted into
common stock. In addition, immediately prior to the effectiveness of a
Qualifying IPO, the holders of Series A, B, D and E preferred stock are entitled
to anti-dilution protection, if applicable, in the form of a dividend payable in
shares, as calculated based upon a formula ("Special Dividend"). At
September 30, 2000, no shares were payable under the terms of the Special
Dividend.
 
                                      F-15

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
7. CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (CONTINUED)
LIQUIDATION
 
    In the event of any liquidation, dissolution or winding up of the Company,
the holders of preferred stock are entitled to a preference in relation to
holders of the Company's common stock with regard to any distribution as
follows: the greater of (i) $2.55 per share for Series A preferred stock, $4.00
per share for Series B preferred stock, $6.00 per share for Series C preferred
stock, $6.75 per share for Series D preferred stock and $7.50 per share for
Series E preferred stock, plus a rate of return of 10% per annum from the
original issue date until the date of payment, or (ii) the amount payable under
the Special Dividend, if applicable. The Company's sale of its assets or an
acquisition of the Company by another entity may also be deemed a liquidation
for purposes of a subsequent distribution of the assets and consideration
allocable to the preferred stockholders; therefore, the preferred stock is
considered temporary equity as presented in the consolidated balance sheet.
 
RIGHTS OF REFUSAL
 
    The holders of preferred stock have certain rights of refusal to participate
in future equity offerings by the Company and are entitled to certain
registration rights with respect to such shares.
 
WARRANTS
 
    At December 31, 1999, the Company had outstanding warrants to purchase an
aggregate of 439,300 shares of the Company's common stock, 405,072 of which were
issued in connection with the Series A preferred stock financing and 34,228 of
which were issued to certain other stockholders in March 1998. The aggregate
fair value of the warrants issued was not material to the Company. The warrants
are exercisable at prices ranging from $12.00 to $15.00 per share, with a
weighted average exercise price of $13.38 per share and a weighted average
remaining contractual life of 1.5 years as they expire at various dates through
February 2002, or earlier upon the occurrence of certain events. At
September 30, 2000, 237,257 warrants with an exercise price of $12.00 per share
remained outstanding and expire in February 2002, or earlier upon the occurrence
of certain events.
 
1997 STOCK OPTION PLAN
 
    The 1997 stock option plan (the "Plan"), as amended, provides for the grant
of incentive stock options and nonqualified stock options to employees,
officers, directors, consultants and advisors of the Company for up to 2,000,000
shares of common stock. The exercise price of each option is set at fair market
value as determined by the Board of Directors and the option's maximum term is
ten years. Options granted under the Plan generally vest over a four year
period. At December 31, 1999 and September 30, 2000, options to purchase 390,354
and 303,729 shares of common stock, respectively, remain available for grant
under the Plan.
 
                                      F-16

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
7. CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (CONTINUED)
    Stock option transactions under the Plan during the years ending
December 31, 1997, 1998 and 1999 and the nine months ended September 30, 2000
are presented below:
 

<TABLE>
<CAPTION>
                                                     NUMBER OF   WEIGHTED-AVERAGE
                                                      SHARES     EXERCISE PRICES
                                                     ---------   ----------------
<S>                                                  <C>         <C>
Balance at December 31, 1996.......................         --           --
  Granted..........................................    976,990        $0.12
  Exercised........................................   (223,370)       $0.01
  Canceled/forfeited...............................    (42,271)       $0.18
                                                     ---------
Balance at December 31, 1997.......................    711,349        $0.15
  Granted..........................................    527,000        $0.62
  Exercised........................................    (84,533)       $0.01
  Canceled/forfeited...............................   (291,566)       $0.06
                                                     ---------
Balance at December 31, 1998.......................    862,250        $0.49
  Granted..........................................    482,500        $0.85
  Exercised........................................    (34,707)       $0.06
  Canceled/forfeited...............................    (43,007)       $0.55
                                                     ---------
Balance at December 31, 1999.......................  1,267,036        $0.64
  Granted (unaudited)..............................    232,500        $0.96
  Exercised (unaudited)............................    (43,007)       $0.30
  Canceled/forfeited (unaudited)...................   (145,875)       $0.65
                                                     ---------
Balance at September 30, 2000 (unaudited)..........  1,310,654        $0.71
                                                     =========
</TABLE>

 
    The following table summarizes information about stock options outstanding
at September 30, 2000 (unaudited):
 

<TABLE>
<CAPTION>
                                        OPTIONS OUTSTANDING                           OPTIONS EXERCISABLE
                        ----------------------------------------------------   ---------------------------------
                            NUMBER       WEIGHTED AVERAGE                          NUMBER
                        OUTSTANDING AT      REMAINING                          EXERCISABLE AT
       RANGE OF         SEPTEMBER 30,    CONTRACTUAL LIFE   WEIGHTED AVERAGE   SEPTEMBER 30,    WEIGHTED AVERAGE
   EXERCISE PRICES           2000            (YEARS)         EXERCISE PRICE         2000         EXERCISE PRICE
   ---------------      --------------   ----------------   ----------------   --------------   ----------------
<S>                     <C>              <C>                <C>                <C>              <C>
$0.01 - $0.25.........      129,154            6.4               $0.16            116,869            $0.15
$0.40 - $0.60.........      450,500            7.4               $0.58            361,438            $0.58
$0.80 - $1.00.........      731,000            8.9               $0.88            163,292            $0.84
                          ---------                                               -------
                          1,310,654                                               641,599
                          =========                                               =======
</TABLE>

 
    The weighted average fair value of options granted during the years ended
December 31, 1997, 1998 and 1999 and the nine months ended September 30, 2000
was approximately $0.03, $0.23, $1.85, and $8.24, respectively.
 
    During the year ended December 31, 1999 and the nine months ended
September 30, 1999 and 2000, in connection with the grant of various stock
options to employees, the Company recorded deferred stock-based compensation of
$470,000, $430,800 and $1,224,300, respectively, representing the difference
between the exercise price and the fair market value of the Company's common
stock for financial reporting purposes on the date such stock options were
granted. Unearned stock-based
 
                                      F-17

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
7. CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (CONTINUED)
compensation is included as a reduction of stockholders' equity (deficit) and is
being amortized to expense over the vesting period of the options in accordance
with FASB Interpretation No. 28. During the year ended December 31, 1999 and the
nine months ended September 30, 1999 and 2000, the Company recorded amortization
of unearned stock-based compensation expense of $98,300, $38,300 and $336,200,
respectively. Also included in stock-based compensation for years ended
December 31, 1998 and 1999 and for the nine months ended September 30, 1999 and
2000 is $52,700, $3,200, $3,200 and $1,769,300, respectively, resulting from the
modification of certain option grants.
 
    During the year ended December 31, 1999 and the nine months ended
September 30, 1999 and 2000, in connection with the grant of stock options to
consultants, the Company recorded stock-based compensation of $4,000, $1,200 and
$103,400, respectively. For purposes of determining this compensation expense,
the fair value of each option grant is estimated on the measurement date using
the Black Scholes option pricing model with the following assumptions used for
the year ended December 31, 1999 and the nine months ended September 30, 1999
and 2000: dividend yield of 0.0%; volatility of 100%; a risk free interest rate
of 6% and an expected life of ten years for all periods.
 
PRO FORMA INFORMATION
 
    Pro forma information regarding net income (loss) is required to be
disclosed in accordance with Statement of Financial Accounting Standards
No. 123, and has been determined as if the Company had accounted for its
employee stock options under the fair value methodology.
 
    For purposes of determining compensation expense, the fair value of each
option grant is estimated on the grant date using the minimum value option
pricing model with the following assumptions used for grants during the years
ended December 31, 1997, 1998 and 1999: dividend yield of 0.0% for all years;
volatility of 0.0% for all years; a risk free interest rate of 7.7%, 7.7% and 6%
for 1997, 1998 and 1999, respectively; and an expected life of six years for all
years. Pro forma information follows:
 

<TABLE>
<CAPTION>
                                                 YEAR ENDED DECEMBER 31,
                                         ---------------------------------------
                                            1997          1998          1999
                                         -----------   -----------   -----------
<S>                                      <C>           <C>           <C>
Actual net loss........................  $(2,981,900)  $(6,402,500)  $(7,445,300)
Pro forma net loss.....................  $(2,985,900)  $(6,429,500)  $(7,548,000)
Actual net loss per share, basic and
  diluted..............................  $     (1.74)  $     (3.12)  $     (3.57)
Pro forma net loss per share, basic and
  diluted..............................  $     (1.74)  $     (3.14)  $     (3.62)
</TABLE>

 
COMMON STOCK RESERVED FOR FUTURE ISSUANCE
 
    At September 30, 2000, a total of 10,019,067 shares of common stock have
been reserved for conversion of preferred stock into common stock. In addition,
1,310,654 and 237,257 shares of common stock have been reserved for issuance
upon the exercise of stock options and warrants, respectively.
 
8. 401(K) PLAN
 
    Effective January 1997, the Company established a deferred compensation plan
(the "401(k) Plan") pursuant to Section 401(k) of the Internal Revenue Code,
whereby substantially all employees
 
                                      F-18

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
8. 401(K) PLAN (CONTINUED)
are eligible to contribute up to 15% of their pretax earnings, not to exceed
amounts allowed under the code. The Company makes contributions to the 401(k)
Plan equal to 100% of the employees' pretax contributions up to 5% of their
eligible compensation. The Company's total contributions to the 401(k) Plan were
$34,400, $89,600, and $118,100 for the years ended December 31, 1997, 1998 and
1999, respectively and $87,000 and $103,800 for the nine months ended
September 30, 1999 and 2000, respectively.
 
9. INCOME TAXES
 
    At December 31, 1999, the Company has both federal and state net operating
loss carryforwards of approximately $9,764,900 and $11,882,700, respectively,
which begin to expire in 2013 and 2003, respectively. The Company also has
foreign net operating loss carryforwards of approximately $6,703,800 which begin
to expire in 2003. Upon certain changes in the ownership of the Company, the
Company's use of net operating losses may be limited.
 
    The components of the deferred tax asset are as follows:
 

<TABLE>
<CAPTION>
                                                           DECEMBER 31,
                                                    ---------------------------
                                                        1998           1999
                                                    ------------   ------------
<S>                                                 <C>            <C>
Net operating loss carryforwards..................  $  3,491,300   $  6,292,600
Research and development credit carryforwards.....       208,800        379,900
Other.............................................       105,700         54,100
                                                    ------------   ------------
                                                       3,805,800      6,726,600
Valuation allowance...............................    (3,805,800)    (6,726,600)
                                                    ------------   ------------
    Net deferred tax asset........................  $         --   $         --
                                                    ============   ============
</TABLE>

 
    Based on a number of factors, including the lack of a history of profits and
the fact that the Company competes in a developing market that is characterized
by rapidly changing technology, management believes that there is sufficient
uncertainty regarding the realization of deferred tax assets such that a full
valuation allowance has been provided.
 
                                      F-19

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
9. INCOME TAXES (CONTINUED)
    A reconciliation of income taxes to the amount computed by applying the
statutory federal income tax rate to the net loss is summarized as follows:
 

<TABLE>
<CAPTION>
                                                YEAR ENDED DECEMBER 31,
                                       ------------------------------------------
                                           1997           1998           1999
                                       ------------   ------------   ------------
<S>                                    <C>            <C>            <C>
Amounts computed at statutory federal
  rate...............................  $ (1,013,600)  $ (2,176,800)  $ (2,531,000)
Permanent differences................        14,700          7,900         41,000
Federal research and development
  credits............................       (28,700)      (119,300)      (110,000)
Change in valuation allowance of
  deferred tax assets................     1,200,700      2,605,000      2,920,800
State taxes..........................      (108,300)      (317,700)      (395,200)
Other................................       (64,800)           900         74,400
                                       ------------   ------------   ------------
                                       $         --   $         --   $         --
                                       ============   ============   ============
</TABLE>

 
10. COMMITMENTS
 
    The Company and its subsidiary lease two office/laboratory facilities and
certain equipment under noncancelable operating leases that expire at various
dates through October 2005. Under the terms of the facilities leases, the
Company is required to pay its proportionate share of property taxes, insurance
and normal maintenance costs.
 
    Future minimum payment obligations under noncancelable operating lease
arrangements are as follows at December 31, 1999:
 

<TABLE>
<S>                                                           <C>
YEAR ENDED DECEMBER 31,
 
  2000......................................................  $  807,600
  2001......................................................     827,900
  2002......................................................     840,600
  2003......................................................     718,800
  2004......................................................     747,600
  Thereafter................................................     611,400
                                                              ----------
                                                              $4,553,900
                                                              ==========
</TABLE>

 
    Rent expense was $242,400, $648,900, $775,800, $575,700 and $623,700 for the
years ended December 31, 1997, 1998 and 1999 and for the nine months ended
September 30, 1999 and 2000, respectively.
 
    In August 2000, the Company entered into a facilities operating lease which
expires on November 30, 2005. Under the lease, the Company will make total
rental payments of $860,100, which includes rent escalation clauses.
 
                                      F-20

<PAGE>
                          ACADIA PHARMACEUTICALS INC.
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
11. SUBSEQUENT EVENTS (UNAUDITED)
 
1997 STOCK OPTION PLAN
 
    In November 2000, the Board of Directors approved an increase in the number
of shares available for issuance under the 1997 stock option plan by 700,000.
Additionally, in October and November 2000, the Company granted options to
purchase 190,000 shares of common stock at a weighted average exercise price of
$1.16 per share. The Company will record additional unearned stock-based
compensation of approximately $1.3 million for option grants to employees.
 
COLLABORATIVE RESEARCH AND LICENSING AGREEMENTS
 
    In December 2000, the Company entered into a five year collaborative drug
discovery agreement with ArQule, Inc. Under the collaboration, the Company will
combine its integrated technology platform with ArQule's Parallel Track
Discovery Program to discover novel small molecule drug candidates directed at
individual genomic targets. The Company and ArQule will share equally in all
future revenues created by the joint discovery programs, including future
milestone, royalty and upfront payments resulting from the out licensing of drug
candidates, if any, and the companies will each obtain certain rights to pursue
independent discovery efforts.
 
INITIAL PUBLIC OFFERING
 
    In December 2000, the Board of Directors authorized management of the
Company to file a registration statement with the Securities and Exchange
Commission permitting the Company to sell shares of its common stock to the
public. If the initial public offering is closed under certain terms, all of the
preferred stock outstanding at September 30, 2000 will convert into shares of
common stock.
 
2000 EQUITY INCENTIVE PLAN
 
    In December 2000, the Board of Directors approved the 2000 equity incentive
plan. Adoption of the 2000 equity incentive plan is subject to stockholder
approval and effective upon the closing of the initial public offering.
 
2000 EMPLOYEE STOCK PURCHASE PLAN
 
    In December 2000, the Board of Directors approved the 2000 employee stock
purchase plan. Adoption of the 2000 employee stock purchase plan is subject to
stockholder approval and effective upon the closing of the initial public
offering.
 
2000 NONEMPLOYEE DIRECTORS' STOCK OPTION PLAN
 
    In December 2000, the Board of Directors approved the 2000 nonemployee
directors' stock option plan. Upon adoption, all newly elected or appointed
nonemployee directors will be entitled to receive an initial option grant and in
subsequent years, all nonemployee directors will be entitled to receive an
automatic annual option grant to each eligible director. Adoption of the 2000
nonemployee directors' stock option plan is subject to stockholder approval and
effective upon the closing of the initial public offering.
 
                                      F-21

<PAGE>
                                 [ACADIA LOGO]

<PAGE>
                 SUBJECT TO COMPLETION, DATED            , 2001
THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY
NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER
TO SELL SECURITIES, AND WE ARE NOT SOLICITING OFFERS TO BUY THESE SECURITIES, IN
ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

<PAGE>
                                 [ACADIA LOGO]
 
                                        SHARES
                                  COMMON STOCK
 
    ACADIA Pharmaceuticals Inc. is offering          shares of its common stock.
This is our initial public offering and no public market currently exists for
our shares. We have applied for approval for quotation of our common stock on
the Nasdaq National Market under the symbol "ACAD." We anticipate that the
initial public offering price will be between $         and $         per share.
 
                            ------------------------
 
                 INVESTING IN OUR COMMON STOCK INVOLVES RISKS.
                    SEE "RISK FACTORS" BEGINNING ON PAGE 5.
 
                             ---------------------
 

<TABLE>
<CAPTION>
                                                               PER SHARE        TOTAL
                                                              ------------   ------------
<S>                                                           <C>            <C>
Public Offering Price.......................................  $              $
Underwriting Discounts and Commissions......................  $              $
Proceeds to ACADIA Pharmaceuticals Inc......................  $              $
</TABLE>

 
    THE UNITED STATES SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
DISAPPROVED THESE SECURITIES, OR DETERMINED IF THIS PROSPECTUS IS TRUTHFUL OR
COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
    ACADIA Pharmaceuticals Inc. has granted the underwriters a 30-day option to
purchase up to an additional          shares of common stock to cover
overallotments.
 
                            ------------------------
 
ROBERTSON STEPHENS INTERNATIONAL                      U.S. BANCORP PIPER JAFFRAY
 
                THE DATE OF THIS PROSPECTUS IS           , 2001

<PAGE>
                                 [ACADIA LOGO]

<PAGE>
 
                                   PART II
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 

ITEM 13. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION
 
    The following table sets forth the costs and expenses, other than
underwriting discounts and commissions, payable by us in connection with the
sale of common stock being registered. All amounts are estimates except the
registration fee, the Nasdaq National Market listing fee and the NASD filing
fee.
 

<TABLE>
<CAPTION>
                                                              AMOUNT TO BE PAID
                                                              -----------------
<S>                                                           <C>
Registration fee............................................     $   19,800
NASD fee....................................................          8,000
Nasdaq National Market listing fee..........................         95,000
Printing and engraving......................................        170,000
Legal fees and expenses.....................................        450,000
Accounting fees and expenses................................        275,000
Blue sky fees and expenses..................................          5,000
Transfer agent fees.........................................         25,000
Miscellaneous...............................................         53,200
                                                                 ----------
Total.......................................................     $1,100,000
                                                                 ==========
</TABLE>

 

ITEM 14. INDEMNIFICATION OF DIRECTORS AND OFFICERS
 
    Under Section 145 of the Delaware General Corporation Law, we have broad
powers to indemnify our directors and officers against liabilities they may
incur in such capacities, including liabilities under the Securities Act.
 
    The form of the underwriting agreement filed as Exhibit 1.1 to this
registration statement provides for indemnification for the underwriters and
their controlling persons, on the one hand and of ACADIA and our controlling
persons on the other hand, for certain liabilities arising under the Securities
Act, the Securities Exchange Act or otherwise.
 
    We maintain directors and officers insurance providing indemnification for
certain of our directors, officers, affiliates, partners or employees for
certain liabilities.
 
    The indemnification provisions in our Bylaws and the indemnification
agreements entered into between us and our directors and executive officers, may
be sufficiently broad to permit indemnification of our officers and directors
for liabilities arising under the 1933 Act.
 

ITEM 15. RECENT SALES OF UNREGISTERED SECURITIES
 
    Since January 1, 1997, we have sold and issued the following unregistered
securities:
 
        1.  On January 23, 1997, we issued an aggregate of 1,523,088 shares of
    our common stock to one accredited investor upon our reincorporation in
    Delaware in consideration for 250 shares of common stock issued by our
    predecessor in Vermont. The 250 shares of the Vermont corporation were
    issued for an aggregate purchase price of $250.
 
        2.  On February 3, 1997, we issued an aggregate of 2,372,548 shares of
    our Series A preferred stock to six accredited investors for an aggregate
    purchase price of $6,049,997. Also on February 3, 1997, we issued to the
    same investors warrants to purchase an aggregate of 237,257 shares of our
    common stock at an exercise price of $6.00 per share and warrants to
    purchase an aggregate of 237,257 shares of our common stock at an exercise
    price of $12.00 per share.
 
                                      II-1

<PAGE>
        3.  On August 12, 1997, we issued an aggregate of 738,384 shares of our
    Series B preferred stock to six accredited investors for an aggregate
    purchase price of $2,953,536.
 
        4.  On September 24, 1997, we issued 1,000,000 shares of our Series C
    preferred stock to one accredited investor for a purchase price of
    $6,000,000.
 
        5.  On December 16, 1997, we issued an aggregate of 237,257 shares of
    our common stock upon the exercise of warrants originally issued on
    February 3, 1997 to the holders of the warrants. The aggregate exercise
    price paid by the holders of the warrants was $1,423,542.
 
        6.  On March 31, 1998, we issued warrants to purchase an aggregate of
    202,043 shares of our common stock with an exercise price of $15.00 per
    share.
 
        7.  On August 26, 1998, we issued an aggregate of 1,581,653 shares of
    our Series D preferred stock to seven accredited investors for an aggregate
    purchase price of $10,676,158.
 
        8.  On May 5, 2000 and June 8, 2000, we issued an aggregate of 2,933,335
    shares of our Series E preferred stock to ten accredited investors for an
    aggregate purchase price of $22,000,013.
 
        9.  At November 30, 2000, we have granted options to purchase an
    aggregate of 1,880,521 shares of our common stock, including options
    subsequently cancelled that then became available for new option grants, to
    directors, employees and consultants under our 1997 stock option plan. The
    exercise prices for such options range from $0.01 to $1.50 per share. At
    November 30, 2000, we have issued an aggregate of 397,117 shares of common
    stock upon the exercise of stock options under our 1997 stock option plan.
 
The offers, sales and issuances of these securities were deemed to be exempt
from registration under the Securities Act in reliance on Section 4(2) of the
Securities Act, and/or Regulation D promulgated thereunder, or Rule 701
promulgated under Section 3(b) of the Securities Act as transactions by an
issuer not involving a public offering or transactions under compensatory
benefit plans and contracts relating to compensation as provided under such
Rule 701. The recipients of securities in each such transaction represented
their intention to acquire the securities for investment only and not with a
view to or for sale in connection with any distribution thereof and appropriate
legends were affixed to the share certificates and warrants issued in such
transactions. All recipients had adequate access, through employment or other
relationships, to information about us.
 

ITEM 16. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES
 
    (a) EXHIBITS
 

<TABLE>
<CAPTION>
EXHIBIT
NUMBER                                    DESCRIPTION OF DOCUMENT
-------                                   -----------------------
<C>                     <S>
         1.1(1)         Form of Underwriting Agreement
         3.1            Registrant's Amended and Restated Certificate of
                          Incorporation, as currently in effect
         3.2(2)         Form of Registrant's Amended and Restated Certificate of
                          Incorporation, to be effective upon the closing of this
                          offering
         3.3            Registrant's Restated Bylaws, as currently in effect
         3.4            Form of Registrant's Amended and Restated Bylaws, to be
                          effective upon the closing of this offering
         4.1            Form of common stock certificate of Registrant
         4.2            Amended and Restated Stockholders Agreement, dated May 5,
                          2000, by and among the Registrant and the stockholders
                          named therein
         4.3            Form of Warrant to Purchase Common Stock, dated February 3,
                          1997
</TABLE>

 
                                      II-2

<PAGE>
 

<TABLE>
<CAPTION>
EXHIBIT
NUMBER                                    DESCRIPTION OF DOCUMENT
-------                                   -----------------------
<C>                     <S>
         5.1(1)         Opinion of Cooley Godward LLP
        10.1            Form of Indemnity Agreement for directors and officers
        10.2            1997 Stock Option Plan and forms of agreement thereunder
        10.3            2000 Equity Incentive Plan and forms of agreement thereunder
        10.4            2000 Non-employee Directors' Stock Option Plan and forms of
                          agreement thereunder
        10.5            2000 Employee Stock Purchase Plan and initial offering
                          thereunder
        10.6            401(k) Plan
        10.7            Employment Letter Agreement, dated December 21, 1998,
                          between the Registrant and Uli Hacksell, Ph.D.
        10.8            Employment Letter Agreement, dated January 31, 1997, between
                          the Registrant and Mark R. Brann, Ph.D.
        10.9            Employment Letter Agreement, dated March 4, 1998, between
                          the Registrant and Thomas H. Aasen
        10.10           Promissory Note, dated May 11, 2000, by Uli Hacksell, Ph.D.
                          in favor of the Registrant
        10.11           Employment Letter Agreement, dated April 17, 1998, between
                          the Registrant and Leonard R. Borrmann, Pharm.D.
        10.12           Separation Agreement and General Release, dated September
                          20, 2000, between the Registrant and Leonard R. Borrmann,
                          Pharm.D.
        10.13           Loan Letter Agreement, dated December 4, 1996, between the
                          Registrant and The Vaekstfonden (The Danish Fund for
                          Industrial Growth)
        10.14(3)        Collaborative Research, Development and License Agreement,
                          dated September 24, 1997, by and among the Registrant,
                          Allergan, Inc. and Vision Pharmaceuticals L.P. (now
                          Allergan Sales, Inc.)
        10.15(3)        Collaborative Research, Development and License Agreement,
                          dated July 26, 1999, by and among the Registrant and
                          Allergan, Inc., Allergan Pharmaceuticals (Ireland)
                          Limited, Inc. and Allergan Sales, Inc.
        10.16(3)        Compound Discovery Collaboration Agreement, dated
                          December 18, 2000, between the Registrant and ArQule, Inc.
        10.17(3)        Assignment of Brann Intellectual Property Rights, dated
                          January 29, 1997, by Mark R. Brann in favor of the
                          Registrant
        10.18           Standard Industrial/Commercial Single-Tenant Lease-Net,
                          dated August 15, 1997, between the Registrant and R.G.
                          Harris Co.
        23.1            Consent of Independent Accountants
        23.2            Consent of Counsel (included in Exhibit 5.1)
        24.1            Power of Attorney (see page II-5)
        27.1            Financial Data Schedule (available in EDGAR format only)
</TABLE>

 
------------------------
 
(1) To be filed by amendment.
 
(2) As proposed to be filed with the Secretary of State of the State of Delaware
    prior to the effectiveness of the offering.
 
(3) This exhibit has been filed separately with the Commission pursuant to an
    application for confidential treatment. The confidential portions of this
    exhibit have been omitted and are marked by an asterisk.
 
    (b) FINANCIAL STATEMENT SCHEDULES
 
                                      II-3

<PAGE>
    Schedules have been omitted because the information required to be set forth
therein is not applicable or is shown in the financial statements or notes
thereto.
 

ITEM 17. UNDERTAKINGS
 
    The undersigned registrant hereby undertakes to provide to the underwriter
at the closing specified in the underwriting agreements certificates in such
denominations and registered in such names as required by the underwriter to
permit prompt delivery to each purchaser.
 
    Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of ACADIA
pursuant to provisions described in Item 14 or otherwise, we have been advised
that in the opinion of the Commission such indemnification is against public
policy as expressed in the Securities Act and is, therefore, unenforceable. In
the event that a claim for indemnification against such liabilities (other than
the payment by us of expenses incurred or paid by a director, officer or
controlling person of ACADIA in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, we will, unless in the opinion
of its counsel the matter has been settled by controlling precedent, submit to a
court of appropriate jurisdiction the question whether such indemnification by
it is against public policy as expressed in the Securities Act and will be
governed by the final adjudication of such issue.
 
    The undersigned Registrant hereby undertakes:
 
    (1) That, for purposes of determining any liability under the Securities
Act, each filing of the registrant's annual report pursuant to Section 13(a) or
15(d) of the Exchange Act (and, where applicable, each filing of an employee
benefit plan's annual report pursuant to Section 15(d) of the Exchange Act) that
is incorporated by reference in the registration statement shall be deemed to be
a new registration statement relating to the securities offered therein and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.
 
    (2) That, for purposes of determining any liability under the Securities
Act, the information omitted from the form of prospectus filed as part of this
registration statement in reliance upon Rule 430A and contained in a form of
prospectus filed by the registrant pursuant to Rule 424(b)(1) or (4) or 497(h)
under the Securities Act shall be deemed to be part of this registration
statement as of the time it was declared effective.
 
    (3) For the purpose of determining any liability under the Securities Act,
each post effective amendment that contains a form of prospectus shall be deemed
to be a new registration statement relating to the securities offered therein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof.
 
                                      II-4

<PAGE>

                                   SIGNATURES
 
    Pursuant to the Securities Act of 1933, the Registrant has duly caused this
registration statement on Form S-1 to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of San Diego, State of
California, on this 21st day of December, 2000.
 

<TABLE>
<S>                                                    <C>  <C>
                                                       ACADIA PHARMACEUTICALS INC.
 
                                                       By:  /s/ ULI HACKSELL
                                                            -----------------------------------------
                                                            Uli Hacksell
                                                            Chief Executive Officer
</TABLE>

 
                               POWER OF ATTORNEY
 
    KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints Uli Hacksell and Thomas H. Aasen, and each of
them, as his true and lawful attorneys in fact and agents, with full power of
substitution and resubstitution, for him and in his name, place, and stead, in
any and all capacities, to sign any and all amendments (including post effective
amendments, exhibits thereto and other documents in connection therewith) to
this registration statement and any subsequent registration statement filed by
the registrant pursuant to Rule 462(b) of the Securities Act of 1933, as
amended, which relates to this registration statement, and to file the same,
with all exhibits thereto, and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto said attorneys in fact and
agents, and each of them, full power and authority to do and perform each and
every act and thing requisite and necessary to be done in connection therewith,
as fully to all intents and purposes as he might or could do in person, hereby
ratifying and confirming all that said attorneys in fact and agents, or any of
them, or their or his substitute or substitutes, may lawfully do or cause to be
done by virtue hereof.
 
    Pursuant to the requirements of the Securities Act of 1933, as amended, this
registration statement has been signed by the following persons in the
capacities and on the dates indicated.
 

<TABLE>
<CAPTION>
                  SIGNATURE                                  TITLE                       DATE
                  ---------                                  -----                       ----
<C>                                            <S>                                 <C>
              /s/ ULI HACKSELL                 Chief Executive Officer and
    ------------------------------------         Director (Principal executive     December 21, 2000
                Uli Hacksell                     officer)
 
                                               Vice President, Chief Financial
             /s/ THOMAS H. AASEN                 Officer, Treasurer and Secretary
    ------------------------------------         (Principal financial and          December 21, 2000
               Thomas H. Aasen                   accounting officer)
 
              /s/ MARK R. BRANN
    ------------------------------------       President, Chief Scientific         December 21, 2000
                Mark R. Brann                    Officer and Director
 
            /s/ LESLIE L. IVERSEN
    ------------------------------------       Chairman of the Board               December 21, 2000
              Leslie L. Iversen
</TABLE>

 
                                      II-5

<PAGE>
 

<TABLE>
<CAPTION>
                  SIGNATURE                                  TITLE                       DATE
                  ---------                                  -----                       ----
<C>                                            <S>                                 <C>
              /s/ THOMAS EKLUND
    ------------------------------------       Director                            December 21, 2000
                Thomas Eklund
 
              /s/ ARNE J.GILLIN
    ------------------------------------       Director                            December 21, 2000
               Arne J. Gillin
 
             /s/ CARL L. GORDON
    ------------------------------------       Director                            December 21, 2000
               Carl L. Gordon
 
            /s/ LESTER J. KAPLAN
    ------------------------------------       Director                            December 21, 2000
              Lester J. Kaplan
 
         /s/ POVL KROGSGAARD-LARSEN
    ------------------------------------       Director                            December 21, 2000
           Povl Krogsgaard-Larsen
 
            /s/ TORSTEN RASMUSSEN
    ------------------------------------       Director                            December 21, 2000
              Torsten Rasmussen
</TABLE>

 
                                      II-6

<PAGE>

                                 EXHIBIT INDEX
 

<TABLE>
<CAPTION>
EXHIBIT
NUMBER                                    DESCRIPTION OF DOCUMENT
-------                                   -----------------------
<C>                     <S>
         1.1(1)         Form of Underwriting Agreement
 
         3.1            Registrant's Amended and Restated Certificate of
                        Incorporation, as currently in effect
 
         3.2(2)         Form of Registrant's Amended and Restated Certificate of
                        Incorporation, to be effective upon the closing of this
                        offering
 
         3.3            Registrant's Restated Bylaws, as currently in effect
 
         3.4            Form of Registrant's Amended and Restated Bylaws, to be
                        effective upon the closing of this offering
 
         4.1            Form of common stock certificate of Registrant
 
         4.2            Amended and Restated Stockholders Agreement, dated May 5,
                        2000, by and among the Registrant and the stockholders named
                        therein
 
         4.3            Form of Warrant to Purchase Common Stock, dated February 3,
                        1997
 
         5.1(1)         Opinion of Cooley Godward LLP
 
        10.1            Form of Indemnity Agreement for directors and officers
 
        10.2            1997 Stock Option Plan and forms of agreement thereunder
 
        10.3            2000 Equity Incentive Plan and forms of agreement thereunder
 
        10.4            2000 Non-employee Directors' Stock Option Plan and forms of
                        agreement thereunder
 
        10.5            2000 Employee Stock Purchase Plan and initial offering
                        thereunder
 
        10.6            401(k) Plan
 
        10.7            Employment Letter Agreement, dated December 21, 1998,
                        between the Registrant and Uli Hacksell, Ph.D.
 
        10.8            Employment Letter Agreement, dated January 31, 1997, between
                        the Registrant and Mark R. Brann, Ph.D.
 
        10.9            Employment Letter Agreement, dated March 4, 1998, between
                        the Registrant and Thomas H. Aasen
 
        10.10           Promissory Note, dated May 11, 2000, by Uli Hacksell, Ph.D.
                        in favor of the Registrant
 
        10.11           Employment Letter Agreement, dated April 17, 1998, between
                        the Registrant and Leonard R. Borrmann, Pharm.D.
 
        10.12           Separation Agreement and General Release, dated September
                        20, 2000, between the Registrant and Leonard R. Borrmann,
                        Pharm.D.
 
        10.13           Loan Letter Agreement, dated December 4, 1996, between the
                        Registrant and The Vaekstfonden (The Danish Fund for
                        Industrial Growth)
 
        10.14(3)        Collaborative Research, Development and License Agreement,
                        dated September 24, 1997, by and among the Registrant,
                        Allergan, Inc. and Vision Pharmaceuticals L.P. (now Allergan
                        Sales, Inc.)
 
        10.15(3)        Collaborative Research, Development and License Agreement,
                        dated July 26, 1999, by and among the Registrant and
                        Allergan, Inc., Allergan Pharmaceuticals (Ireland) Limited,
                        Inc. and Allergan Sales, Inc.
</TABLE>

 

<PAGE>
 

<TABLE>
<CAPTION>
EXHIBIT
NUMBER                                    DESCRIPTION OF DOCUMENT
-------                                   -----------------------
<C>                     <S>
        10.16(3)        Compound Discovery Collaboration Agreement, dated
                        December 18, 2000, between the Registrant and ArQule, Inc.
 
        10.17(3)        Assignment of Brann Intellectual Property Rights, dated
                        January 29, 1997, by Mark R. Brann in favor of the
                        Registrant
 
        10.18           Standard Industrial/Commercial Single-Tenant Lease-Net,
                        dated August 15, 1997, between the Registrant and R.G.
                        Harris Co.
 
        23.1            Consent of Independent Accountants
 
        23.2            Consent of Counsel (included in Exhibit 5.1)
 
        24.1            Power of Attorney (see page II-5)
 
        27.1            Financial Data Schedule (available in EDGAR format only)
</TABLE>

 
------------------------
 
(1) To be filed by amendment.
 
(2) As proposed to be filed with the Secretary of State of the State of Delaware
    prior to the effectiveness of the offering.
 
(3) This exhibit has been filed separately with the Commission pursuant to an
    application for confidential treatment. The confidential portions of this
    exhibit have been omitted and are marked by an asterisk.





<PAGE>

                              AMENDED AND RESTATED
                          CERTIFICATE OF INCORPORATION
                                       OF
                           ACADIA PHARMACEUTICALS INC.


         ACADIA Pharmaceuticals Inc., a corporation organized and existing under
and by virtue of the General Corporation Law of the State of Delaware (the
"Corporation"), does hereby certify as follows:

                  FIRST: The name of the Corporation is: ACADIA 
Pharmaceuticals Inc.

                  SECOND: The Corporation's original Certificate of
Incorporation was filed with the Secretary of State on January 16, 1997 under
the name Receptor Technologies, Inc.

                  THIRD: The Amended and Restated Certificate of Incorporation
of this Corporation, in the form attached hereto as Exhibit A, has been duly
adopted by the Board of Directors and stockholders in accordance with the
provisions of Sections 228, 242 and 245 of the General Corporation Law of the
State of Delaware. At least 66 2/3% of each of the outstanding Series A, Series
B, Series C and Series D Preferred Stock of the Company, each voting as a
separate class, and at least 50% of the outstanding Common Stock and Series A,
Series B, Series C and Series D Preferred Stock of the Company, voting as a
separate class, approved this Restated Certificate of Incorporation by written
consent in accordance with Section 228
 of the General Corporation Law of the
State of Delaware and written notice of such was given by the Corporation in
accordance with said Section 228.

                  FOURTH: The Amended and Restated Certificate of Incorporation
so adopted reads in full as set forth in Exhibit A attached hereto and is hereby
incorporated by reference.

                  IN WITNESS WHEREOF, ACADIA Pharmaceuticals Inc. has caused
this Amended and Restated Certificate of Incorporation to be signed by its Chief
Executive Officer this 28th day of April, 2000.



                                           ACADIA PHARMACEUTICALS INC.




                                           By: /s/ Leonard R. Borrmann
                                              ---------------------------------
                                                 Leonard R. Borrmann,
                                                 Chief Executive Officer


                                       1.


<PAGE>

                                    EXHIBIT A


                              AMENDED AND RESTATED
                          CERTIFICATE OF INCORPORATION
                                       OF
                           ACADIA PHARMACEUTICALS INC.


                                       I.

         The name of this Corporation is ACADIA PHARMACEUTICALS INC.

                                      II.

         The address of its registered office in the State of Delaware is
Corporation Service Company, 1013 Centre Road, in the City of Wilmington, County
of New Castle. The name of its registered agent at such address is Corporation
Service Company.

                                      III.

         The nature of the business or purposes to be conducted or promoted by
the Corporation is as follows:

         To engage in any lawful act or activity for which corporations may be
organized under the General Corporation Law of Delaware

                                      IV.

         The total number of shares of all classes of stock which the
Corporation shall have authority to issue is (i) 14,218,712 shares of Common
Stock, $0.0001 par value per share ("Common Stock") and (ii) 10,019,067 shares
of Preferred Stock, $0.01 par value per share ("Preferred Stock").

         The following is a statement of the designations and the powers,
privileges and rights, and the qualifications, limitations or restrictions
thereof in respect of each class of capital stock of the Corporation.

         A. COMMON STOCK

                  1. GENERAL. The voting, dividend and liquidation rights of the
holders of the Common Stock are subject to and qualified by the rights of the
holders of the Preferred Stock of any series as may be designated by the Board
of Directors upon any issuance of the Preferred Stock of any series.

                  2. VOTING. Subject to Section C.3. of this Article IV, the
holders of the Common Stock are entitled to one vote for each share held at all
meetings of stockholders (and written actions in lieu of meetings). There shall
be no cumulative voting. The number of 


                                       1.


<PAGE>

authorized shares of Common Stock may be increased or decreased (but not 
below the number of shares thereof then outstanding or issuable upon the 
exercise or conversion of any securities exercisable for or convertible into 
Common Stock) by the affirmative vote of the holders of majority of the stock 
of the Corporation entitled to vote, irrespective of the provisions of 
Section 242(b)(2) of the General Corporation Law of Delaware.

                  3. DIVIDENDS. Dividends may be declared and paid on the Common
Stock from funds lawfully available therefor as and when determined by the Board
of Directors and subject to any preferential dividend rights of any then
outstanding Preferred Stock.

                  4. LIQUIDATION. Upon the dissolution or liquidation of the
Corporation, whether voluntary or involuntary, holders of Common Stock will be
entitled to receive all assets of the Corporation available for distribution to
its stockholders, subject to any preferential rights of any then outstanding
Preferred Stock.

         B. PREFERRED STOCK.

         Preferred Stock may be issued from time to time in one or more series,
each of such series to have such terms as stated or expressed herein and in the
resolution or resolutions providing for the issue of such series adopted by the
Board of Directors of the Corporation as hereinafter provided. Any shares of
Preferred Stock which may be redeemed, purchased or acquired by the Corporation
may be reissued except as otherwise provided by law. Different series of
Preferred Stock shall not be construed to constitute different classes of shares
for the purposes of voting by classes unless expressly provided.

         C. SERIES PREFERRED STOCK.

         An aggregate of 2,372,548 shares of the authorized shares of Preferred
Stock of the Corporation are hereby designated "Series A Preferred Stock;" an
aggregate of 738,384 shares of the authorized shares of Preferred Stock are
hereby designated "Series B Preferred Stock"; an aggregate of 1,000,000 shares
of the authorized shares of Preferred Stock are hereby designated "Series C
Preferred Stock;" an aggregate of 1,908,135 shares of the authorized shares of
Preferred Stock are hereby designated "Series D Preferred Stock"; and an
aggregate of 4,000,000 shares of Preferred Stock are hereby designated as the
"Series E Preferred Stock." The Series A Preferred Stock, the Series B Preferred
Stock, the Series C Preferred Stock, the Series D Preferred Stock and the Series
E Preferred Stock are collectively referred to herein as the "Series Preferred
Stock" with the following rights, preferences, powers, privileges and
restrictions, qualifications and limitations.

                  1. DIVIDENDS.

                           a. The Corporation shall not declare or pay any
distributions (as defined below) on shares of Common Stock until the holders of
the Series Preferred Stock then outstanding shall have first received, or
simultaneously receive, a distribution on each outstanding share of Series
Preferred Stock in an amount at least equal to the product of (i) the per share
amount, if any, of the dividends or other distributions to be declared, paid or
set aside for the Common Stock, multiplied by (ii) the number of whole shares of
Common Stock into which such share of Preferred Stock would then (a) with
respect to the Series A, Series B, Series 


                                       2.


<PAGE>

D Preferred Stock and Series E Preferred Stock, be reclassified had the 
payment of the Special Dividend (as defined in subsection c. below) been 
declared and paid and had the expiry of the Series Preferred Stock 
preferences occurred immediately prior to the declaration and payment of such 
distribution, and (b) with respect to Series C Preferred Stock be convertible 
into.

                           b. For purposes of this Section C.1., unless the
context requires otherwise, "distribution" shall mean the transfer of cash or
property without consideration, whether by way of dividend or otherwise, payable
other than in Common Stock or other securities of the Corporation, or the
purchase or redemption of shares of the Corporation (other than repurchases of
Common Stock held by employees, officers or directors of, or consultants to, the
Corporation upon termination of their employment or services pursuant to
agreements providing for such repurchase at a price equal to the original issue
price of such shares and other than redemptions in liquidation or dissolution of
the Corporation) for cash or property, including any such transfer, purchase or
redemption by a subsidiary of this Corporation.

                           c. The Corporation shall immediately prior to the
effectiveness of a public offering described in Section C.5.a. below, declare
and pay on the Series Preferred Stock a "Special Dividend," payable as follows:

                                    (a) with respect to the Series A Preferred
Stock, payable in shares of Series A Preferred Stock, equal to X = [A * B] - A,
where

                                             (1) A equals the aggregate number
of shares of Series A Preferred Stock outstanding immediately prior to the
declaration of the Special Dividend;

                                             (2) B equals $2.55 divided by the
then current Series A Adjustment Factor (as defined below); and

                                             (3) X equals the number of shares
of Series A Preferred Stock to be issued in the dividend.

                                    (b) with respect to the Series B Preferred
Stock, payable in shares of Series B Preferred Stock, equal to X = [A * B] - A,
where

                                             (1) A equals the aggregate number
of shares of Series B Preferred Stock outstanding immediately prior to the
declaration of the Special Dividend;

                                             (2) B equals $4.00 divided by the
then current Series B Adjustment Factor (as defined below); and

                                             (3) X equals the number of shares
of Series B Preferred Stock to be issued in the dividend.

                           d. The Corporation shall immediately prior to the
effectiveness of a public offering described in Section C.5.c. below, declare
and pay on the Series D Preferred 


                                       3.


<PAGE>

Stock a "Special Dividend," payable in shares of Series D Preferred Stock, 
equal to X = [A * B] - A, where

                                    (i) A equals the aggregate number of shares
of Series D Preferred Stock outstanding immediately prior to the declaration of
the Special Dividend;

                                    (ii) B equals $6.75 divided by the then
current Series D Adjustment Factor (as defined below); and

                                    (iii) X equals the number of shares of
Series D Preferred Stock to be issued in the dividend.

                           e. The Corporation shall immediately prior to the
effectiveness of a public offering described in Section C.5.d. below, declare
and pay on the Series E Preferred Stock a "Special Dividend," payable in shares
of Series E Preferred Stock, equal to X = [A * B] - A, where

                                    (i) A equals the aggregate number of shares
of Series E Preferred Stock outstanding immediately prior to the declaration of
the Special Dividend;

                                    (ii) B equals $7.50 divided by the then
current Series E Adjustment Factor (as defined below); and

                                    (iii) X equals the number of shares of
Series E Preferred Stock to be issued in the dividend.

                  The Special Dividend payable with respect to the Series A
Preferred Stock is referred to herein as the Special Series A Dividend, the
Special Dividend payable with respect to the Series B Preferred Stock is
referred to herein as the Special Series B Dividend, the Special Dividend
payable with respect to the Series D Preferred Stock is referred to herein as
the Special Series D Dividend and the Special Dividend payable with respect to
the Series E Preferred Stock is referred to herein as the Special Series E
Dividend. Any fraction of a share of Series Preferred Shares shall be adjusted
upward to the nearest full number of shares and no fraction of a share shall be
payable in cash.

                  2. LIQUIDATION, DISSOLUTION OR WINDING UP; CERTAIN MERGERS,
CONSOLIDATIONS AND ASSET SALES.


                           a. In the event of any voluntary or involuntary
liquidation, dissolution or winding up of the corporation, the holders of shares
of Series Preferred Stock then outstanding shall be entitled to be paid out of
the assets of the Corporation available for distribution to its stockholders
before any payment shall be made to the holders of Common Stock or any other
class or series of stock ranking on liquidation junior to the Series Preferred
Stock (such Common Stock and other stock being collectively referred to as
"Junior Stock") by reason of their ownership thereof, an amount equal to the
greater of (i) (A) with respect to the Series A Preferred Stock, $2.55 per
share, with respect to the Series B Preferred Stock, $4.00 per share, with
respect to the Series C Preferred Stock, $6.00 per share, with respect to the
Series D Preferred Stock, $6.75 per share, and with respect to the Series E
Preferred Stock, $7.50 per 


                                       4.


<PAGE>

share (in each case, subject to appropriate adjustment in the event of any 
stock dividend, stock split, combination or other similar recapitalization 
affecting such shares), plus any dividends declared but unpaid thereon, plus 
(B) a rate of return on the amount determined under the foregoing clause (A) 
equal to 10% per annum from the Original Issue Date (as defined below) 
corresponding to such Series Preferred Stock until the date of payment 
thereof to the holders of the Series Preferred Stock or (ii) such amount per 
share as would have been payable had the Special Dividend been declared and 
paid and had each such share been reclassified or converted, as the case may 
be, into Common Stock pursuant to Section C.5 immediately prior to such 
liquidation, dissolution or winding up. If upon any such liquidation, 
dissolution or winding up of the Corporation the remaining assets of the 
Corporation available for distribution to its stockholders shall be 
insufficient to pay the holders of shares of Series Preferred Stock the full 
amount to which they shall be entitled, then the holders of shares of Series 
Preferred Stock shall share ratably in any distribution of such remaining 
assets and funds of the Corporation in proportion to the respective amounts 
which would otherwise be payable in respect of the shares held by them upon 
such distribution if all amounts payable on or with respect to such shares be 
paid in full.

                           b. Upon completion of the distribution provided for
in Subsection 2.a. above, all of the assets remaining in the Corporation, if
any, shall be distributed pro rata among the holders of the Common Stock, based
upon the number of shares of Common Stock held by such holder.

                           c. In the event of any merger or consolidation of the
Corporation into or with another corporation (except one in which the holders of
capital stock of the Corporation immediately prior to such merger or
consolidation continue to hold at least 80% by voting power of the capital stock
of the surviving corporation), or the sale of all or substantially all the
assets of the Corporation, if the holders of at least a majority of either (i)
the then outstanding shares of Series A, B, D and E Preferred Stock taken
together as single class or (ii) the then outstanding shares of Series C
Preferred Stock so elect by giving written notice thereof to the Corporation at
least three days before the effective date of such event, then such merger,
consolidation or asset sale shall be deemed to be a liquidation of the
Corporation with respect to all of the Series Preferred Stock, and all
consideration payable to the holders of shares of Series Preferred Stock (in the
case of a merger or consolidation), or all consideration payable to the
Corporation and allocable to the holders of shares of Series Preferred Stock,
together with all other available assets of the Corporation which are allocable
to the holders of shares of Series Preferred Stock (in the case of an asset
sale), shall be distributed to the holders of shares of Series Preferred Stock
in accordance with Subsection 2.a. above. The Corporation shall promptly provide
to the holders of shares of Series Preferred Stock such information concerning
the terms of such merger, consolidation or asset sale and the value of the
assets of the Corporation as may reasonably be requested by the holders of
Series Preferred Stock in order to assist them in determining whether to make
such an election. If the holders of the Series Preferred Stock make such an
election, the Corporation shall use its best efforts to amend the agreement or
plan of merger or consolidation to adjust the rate at which the shares of
capital stock of the Corporation are converted into or exchanged for cash, new
securities or other property to give effect to such election. The amount deemed
distributed to the holders of Series Preferred Stock upon any such merger or
consolidation shall be the cash or the value of the property, rights or
securities distributed to such holders by the acquiring person, firm or other
entity. The value of such 


                                       5.


<PAGE>

property, rights or other securities shall be determined in good faith by the 
Board of Directors of the Corporation. Upon the distribution of assets to the 
holders of Series Preferred Stock making the election under this Subsection 
2.c., the shares of Series Preferred Stock held by such holders shall be 
deemed surrendered and shall be canceled. If no notice of the election 
permitted by this Subsection 2.c. is given, the provisions of Subsection 4.f. 
shall apply.

                  3. VOTING.

                           a. Each holder of outstanding shares of Series
Preferred Stock shall be entitled at any meeting of stockholders, or pursuant to
an action by written consent in lieu of a meeting, to the number of votes equal
to the number of whole shares of Common Stock into which the shares of Series
Preferred Stock held by such holder would be reclassified had the issuance of
the Special Dividend and the expiry of the preferences or the conversion, as the
case may be, of the Series Preferred Stock pursuant to Section C.5. herein
occurred immediately prior to the record date for such meeting of stockholders
of the Corporation (and written actions of stockholders in lieu of meetings)
with respect to any and all matters presented to the stockholders of the
Corporation for their action or consideration. Except as provided by law or by
the provisions of Subsections 3.b. through 3.e. below, holders of Series A
Preferred Stock, Series B Preferred Stock, Series C Preferred Stock, Series D
Preferred Stock and Series E Preferred Stock shall vote together with the
holders of Common Stock as a single class.

                           b. Subject to Section C.5. herein, the Corporation
shall not amend, alter or repeal the preferences, special rights or other powers
of any series of the Series Preferred Stock so as to affect adversely any series
of Series Preferred Stock, without the written consent or affirmative vote of
holders of at least two-thirds (2/3) of the then outstanding shares of (i)
Series A, B, D and E Preferred Stock taken together as a single class and (ii)
Series C Preferred Stock, given in writing or by vote at a meeting, each
consenting or voting (as the case may be) separately as a class, including but
not limited to any of the following:

                                    (i) authorizing any shares of capital stock
with preference or priority over any series of the Series Preferred Stock or,
except with respect to shares authorized for and issued to Corporate Partners
(defined below) as provided in Subsection 3.c. below, on a parity with, any
series of the Series Preferred Stock as to voting or the right to receive either
dividends or amounts distributable upon liquidation, dissolution or winding up
of the Corporation;

                                    (ii) any sale, conveyance, or other
disposition of or encumbrance (other than pursuant to a credit arrangement in
the ordinary course of business) of all or substantially all of the
Corporation's property or business or merging into or consolidating with any
other corporation (other than a wholly owned subsidiary corporation) or
effecting any transaction or series of related transactions in which more than
50% of the voting power of the Corporation is disposed of or effecting any
reorganization or recapitalization of the Corporation, in each case involving a
transaction in which the value of the Corporation immediately prior to the
effective date thereof (determined based on the aggregate cash consideration
paid to the Corporation and its stockholders on such effective date in respect
of such transaction) (the "Company Valuation") is less than $42.6 million;


                                       6.


<PAGE>

                                    (iii) increasing the authorized number of
shares of any series of Series Preferred Stock or, except with respect to shares
authorized for and issued to Corporate Partners as provided in Subsection 3.c.
below, the total number of shares of Preferred Stock; or

                                    (iv) except with respect to shares
authorized for and issued to Corporate Partners as provided in Subsection 3.c.
below or a change in the authorized number of shares of Common Stock necessary
in connection with any adjustment pursuant to the antidilution protections or
Special Dividend provisions hereof, increasing the authorized number of shares
of Common Stock.

                           c. Subject to Section C.5. herein, the Corporation
shall not amend, alter or repeal the preferences, special rights or other powers
of any series of the Series Preferred Stock so as to affect adversely any series
of Series Preferred Stock, without the written consent or affirmative vote of
holders of at least two-thirds (2/3) of the then outstanding shares of Series A,
B, C, D and E Preferred Stock taken together as a single class, given in writing
or by vote at a meeting, consenting or voting (as the case may be) separately as
a class, including but not limited to any of the following:

                                    (i) authorizing any shares of capital stock
on a parity with any series of the Series Preferred Stock as to voting or the
right to receive either dividends or amounts distributable upon liquidation,
dissolution or winding up of the Corporation, which shares are authorized for
and issued to a Corporate Partner;

                                    (ii) any sale, conveyance, or other
disposition of or encumbrance (other than pursuant to a credit arrangement in
the ordinary course of business) of all or substantially all of the
Corporation's property or business or merging into or consolidating with any
other corporation (other than a wholly owned subsidiary corporation) or
effecting any transaction or series of related transactions in which more than
50% of the voting power of the Corporation is disposed of or effecting any
reorganization or recapitalization of the Corporation, in each case at a Company
Valuation of at least $42.6 million; or

                                    (iii) increasing the authorized number of
shares of Preferred Stock, which shares are authorized for and issued to a
Corporate Partner; or

                                    (iv) increasing the authorized number of
shares of Common Stock, which shares are authorized for issuance upon conversion
of shares issued to a Corporate Partner.

For purposes of this Section C.3, the term "Corporate Partner" shall mean a
third party with whom the Corporation has entered into a strategic relationship
pursuant to a written BONA FIDE collaboration agreement involving payments to
the Company and diligence obligations by such third party.

                           d. The Corporation shall not, without the written
consent or affirmative vote of the holders of at least sixty-seven percent (67%)
of the then outstanding shares of Series C Preferred Stock, given in writing or
by vote at a meeting, consenting or voting (as the case may be) separately as a
class, increase the maximum number of directors constituting the Board of
Directors to a number in excess of nine (9).


                                       7.


<PAGE>


                           e. The holders of the Series C Preferred Stock,
voting together as a separate class, shall be entitled to elect one (1) director
of the Corporation. The holders of the Series E Preferred Stock, voting together
as a separate class, shall be entitled to elect one (1) director of the
Corporation. The holders of the Series Preferred Stock together with the holders
of Common Stock shall be entitled to elect up to seven (7) directors of the
Corporation. At any meeting (or in a written consent in lieu thereof) held for
the purpose of electing directors, the presence in person or by proxy (or the
written consent) of the holders of a majority of the shares of the Series C
Preferred Stock then outstanding shall constitute a quorum of the Series C
Preferred Stock for the election of the director to be elected solely by the
holders of the Series C Preferred Stock and the presence in person or by proxy
(or the written consent) of the holders of a majority of the shares of the
Series E Preferred Stock then outstanding shall constitute a quorum of the
Series E Preferred Stock for the election of the director to be elected solely
by the holders of the Series E Preferred Stock. A vacancy in any directorship
elected by the holders of the Series C Preferred Stock shall be filled only by
vote or written consent of the holders of the Series C Preferred Stock, a
vacancy in any directorship elected by the holders of the Series E Preferred
Stock shall be filled only by vote or written consent of the holders of the
Series E Preferred Stock and a vacancy in any directorship elected by the
holders of the Series Preferred and the Common Stock shall be filled only by
vote or written consent of such holders. A director elected by the holders of
Series C Preferred Stock may be removed without cause only by vote of the
holders of a majority of the outstanding shares of Series C Preferred Stock, a
director elected by the holders of Series E Preferred Stock may be removed
without cause only by vote of the holders of a majority of the outstanding
shares of Series E Preferred Stock and a director elected by the holders of the
Series Preferred and the Common Stock may be removed without cause only by vote
of the holders of a majority of the outstanding shares of the Series Preferred
and the Common Stock taken together as a single class.

                  4. ADJUSTMENT FACTOR

                  The Corporation shall at all times calculate an adjustment
factor (the "Adjustment Factor"). The Adjustment Factor with respect to the
Series A Preferred Stock shall initially be $2.55 (the "Series A Adjustment
Factor"); the Adjustment Factor with respect to the Series B Preferred Stock
shall initially be $4.00 (the "Series B Adjustment Factor"); the Adjustment
Factor with respect to the Series C Preferred Stock shall initially be $6.00
(the "Series C Adjustment Factor"); the Adjustment Factor with respect to the
Series D Preferred Stock shall initially be $6.75 (the "Series D Adjustment
Factor") and the Adjustment Factor with respect to the Series E Preferred Stock
shall initially be $7.50 (the "Series E Adjustment Factor"). Such initial
Adjustment Factor shall be subject to adjustment as provided below.

                           a. ADJUSTMENTS TO ADJUSTMENT FACTOR FOR DILUTING
ISSUES:

                                    (i) SPECIAL DEFINITIONS. For purposes of
this Section 4, the following definitions shall apply:

                                             (a) "OPTION" shall mean rights,
options or warrants to subscribe for, purchase or otherwise acquire Common Stock
or Convertible Securities, excluding options or warrants described in subsection
4.a.(i)(d)(4) below.


                                       8.


<PAGE>

                                             (b) "ORIGINAL ISSUE DATE" with
respect to each series of Series Preferred Stock shall mean the date on which
such series of Series Preferred Stock was first issued.

                                             (c) "CONVERTIBLE SECURITIES" shall
mean any evidences of indebtedness, shares or other securities directly or
indirectly convertible into or exchangeable for Common Stock.

                                             (d) "ADDITIONAL SHARES OF COMMON
STOCK" shall mean all shares of Common Stock issued (or, pursuant to Subsection
4.a(iii) below, deemed to be issued) by the Corporation after the Original Issue
Date, other than shares of Common Stock issued or issuable:

                                                    (1) upon conversion of any
Convertible Securities outstanding on the Original Issue Date, or upon exercise
of any Option outstanding on the Original Issue Date (including Options issued
on such Date);

                                                    (2) as a dividend or 
distribution on Series Preferred Stock or in connection with the
reclassification or conversion, as the case may be, of the Series Preferred
Stock pursuant to Section C.5. herein;

                                                    (3) by reason of a dividend,
stock split, split-up or other distribution on shares of Common Stock that is
covered by Subsection 4.b. or 4.c. below;

                                                    (4) to employees or
directors of, or consultants to, the Corporation pursuant to a plan or
arrangement adopted by the Board of Directors of the Corporation;

                                                    (5) in connection with bona
fide strategic transactions involving the Company and other entities, including
(i) joint ventures, manufacturing, marketing or distribution arrangements, or
(ii) collaboration or technology transfer arrangements; provided that each such
transaction and the issuance of shares pursuant thereto has been approved by the
Company's Board of Directors and the arrangement involves due diligence
obligations (if applicable);

                                                    (6) upon the exercise of 
warrants to purchase Common Stock at an exercise price of $12.00 per share for
an aggregate 237,257 shares, issued by the Company to certain of its
stockholders on February 3, 1997; or

                                                    (7) upon the exercise of 
warrants to purchase Common Stock at an exercise price of $15.00 per share for
an aggregate 202,043 shares, issued by the Company to certain of its
stockholders on March 31, 1998.

                                    (ii) NO ADJUSTMENT OF ADJUSTMENT FACTOR. No
adjustment in the Adjustment Factor shall be made under this Section 4.a unless
(a) the consideration per share (determined pursuant to Subsection 4.a(v)) for
an Additional Share of Common Stock issued or deemed to be issued by the
Corporation is less than the applicable Adjustment Factor with 


                                       9.


<PAGE>

respect to the applicable series of Series Preferred Stock in effect on the 
date of, and immediately prior to, the issue of such Additional Shares of 
Common Stock, and (b) prior to such issuance, the Corporation did not receive 
written consent from the holders of all the then outstanding shares of the 
applicable series of Series Preferred Stock otherwise subject to such 
adjustment that no such adjustment shall be made as the result of the 
issuance of Additional Shares of Common Stock.

                                    (iii) DEEMED ISSUANCE OF ADDITIONAL SHARES
OF COMMON STOCK. If the Corporation at any time or from time to time after the
Original Issue Date shall issue any Options or Convertible Securities or shall
fix a record date for the determination of holders of any class of securities
entitled to receive any such Options or Convertible Securities, then the maximum
number of shares of Common Stock (as set forth in the instrument relating
thereto without regard to any provision contained therein for a subsequent
adjustment of such number) issuable upon the exercise of such Options or, in the
case of Convertible Securities and Options therefor, the conversion or exchange
of such Convertible Securities, shall be deemed to be Additional Shares of
Common Stock issued as of the time of such issue or, in case such a record date
shall have been fixed, as of the close of business on such record date, provided
that Additional Shares of Common Stock shall not be deemed to have been issued
unless the consideration per share (determined pursuant to Subsection 4.a(v)
hereof) of such Additional Shares of Common Stock would be less than the
applicable Adjustment Factor in effect on the date of and immediately prior to
such issue, or such record date, as the case may be, and provided further that
in any such case in which Additional Shares of Common Stock are deemed to be
issued:

                                             (a) No further adjustment in the
Adjustment Factor shall be made upon the subsequent issue of Convertible
Securities or shares of Common Stock upon the exercise of such Options or
conversion or exchange of such Convertible Securities;

                                             (b) If such Options or Convertible
Securities by their terms provide, with the passage of time or otherwise, for
any increase in the consideration payable to the Corporation, upon the exercise,
conversion or exchange thereof, the Adjustment Factor computed upon the original
issue thereof (or upon the occurrence of a record date with respect thereto),
and any subsequent adjustments based thereon, shall, upon any such increase
becoming effective, be recomputed to reflect such increase insofar as it affects
such Options or the rights of conversion or exchange under such Convertible
Securities;

                                             (c) Upon the expiration or
termination of any unexercised Option, the Adjustment Factor shall not be
readjusted, but the Additional Shares of Common Stock deemed issued as the
result of the original issue of such Option shall not be deemed issued for the
purposes of any subsequent adjustment of the Adjustment Factor;

                                             (d) In the event of any change in
the number of shares of Common Stock issuable upon the exercise, conversion or
exchange of any Option or Convertible Security, including, but not limited to, a
change resulting from the anti-dilution provisions thereof, the Adjustment
Factor then in effect shall forthwith be readjusted to such Adjustment Factor as
would have been obtained had the adjustment which was made upon the 


                                       10.


<PAGE>


issuance of such Option or Convertible Security not exercised or converted 
prior to such change been made upon the basis of such change; and

                                             (e) No readjustment pursuant to
clause (b) or (d) above shall have the effect of increasing the Adjustment
Factor to an amount which exceeds the lower of (i) the Adjustment Factor on the
original adjustment date, or (ii) the Adjustment Factor that would have resulted
from any issuance of Additional Shares of Common Stock between the original
adjustment date and such readjustment date.

         In the event the Corporation, after the Original Issue Date, amends the
terms of any Options or Convertible Securities (whether such Options or
Convertible Securities were outstanding on the Original Issue Date or were
issued after the Original Issue Date), then such Options or Convertible
Securities, as so amended, shall be deemed to have been issued after the
Original Issue Date and the provisions of this Subsection 4.a. shall apply.

                                    (iv) ADJUSTMENT OF ADJUSTMENT FACTOR UPON
ISSUANCE OF ADDITIONAL SHARES OF COMMON STOCK. In the event the Corporation
shall at any time after the Original Issue Date issue Additional Shares of
Common Stock (including Additional Shares of Common Stock deemed to be issued
pursuant to Subsection 4.a(iii), but excluding shares issued as a stock split or
combination as provided in Subsection 4.b or upon a dividend or distribution as
provided in Subsection 4.c), without consideration or for a consideration per
share less than the applicable Adjustment Factor in effect on the date of and
immediately prior to such issue, then and in such event, such Adjustment Factor
shall be reduced, concurrently with such issue, to a price (calculated to the
nearest cent) determined by multiplying such Adjustment Factor by a fraction,
(A) the numerator of which shall be (1) the number of shares of Common Stock
outstanding immediately prior to such issue plus (2) the number of shares of
Common Stock which the aggregate consideration received or to be received by the
Corporation for the total number of Additional Shares of Common Stock so issued
would purchase at such Adjustment Factor; and (B) the denominator of which shall
be the number of shares of Common Stock outstanding immediately prior to such
issue plus the number of such Additional Shares of Common Stock so issued;
PROVIDED THAT, (i) for the purpose of this subsection 4.a(iv), all shares of
Common Stock issuable upon exercise or conversion of options or Convertible
Securities outstanding immediately prior to such issue shall be deemed to be
outstanding, and (ii) the number of shares of Common Stock deemed issuable upon
exercise or conversion of such outstanding options and Convertible Securities
shall not give effect to any adjustments to the exercise price or conversion
rate of such options or Convertible Securities resulting from the issuance of
Additional Shares of Common Stock that is the subject of this calculation.

                                    (v) DETERMINATION OF CONSIDERATION. For
purposes of this Subsection 4.a, the consideration received by the Corporation
for the issue of any Additional Shares of Common Stock shall be computed as
follows:

                                             (a) CASH AND PROPERTY: Such
consideration shall:

                                                    (1) insofar as it consists 
of cash, be computed at the aggregate of cash received by the Corporation,
excluding amounts paid or payable for accrued interest;


                                       11.


<PAGE>

                                                    (2) insofar as it consists 
of property other than cash, be computed at the fair market value thereof at the
time of such issue, as determined in good faith by the Board of Directors; and

                                                    (3) in the event Additional
Shares of Common Stock are issued together with other shares or securities or
other assets of such Corporation for consideration which covers both, be the
proportion of such consideration so received, computed as provided in clauses
(1) and (2) above, as determined in good faith by the Board of Directors.

                                             (b) OPTIONS AND CONVERTIBLE
SECURITIES. The consideration per share received by the Corporation for
Additional Shares of Common Stock deemed to have been issued pursuant to
Subsection 4.a.(iii), relating to Options and Convertible Securities, shall be
determined by dividing:

                                             (x) the total amount, if any,
received or receivable by the Corporation as consideration for the issue of such
Options or Convertible Securities, plus the minimum aggregate amount of
additional consideration (as set forth in the instruments relating thereto,
without regard to any provision contained therein for a subsequent adjustment of
such consideration) payable to the Corporation upon the exercise of such Options
or the conversion or exchange of such Convertible Securities, or in the case of
Options for Convertible Securities, the exercise of such Options for Convertible
Securities and the conversion or exchange of such Convertible Securities, by

                                             (y) the maximum number of shares of
Common Stock (as set forth in the instruments relating thereto, without regard
to any provision contained therein for a subsequent adjustment of such number)
issuable upon the exercise of such Options or the conversion or exchange of such
Convertible Securities.

                                    (vi) MULTIPLE CLOSING DATES. In the event
the Corporation shall issue on more than one date Additional Shares of Common
Stock which are comprised of shares of the same series or class of Preferred
Stock, and such issuance dates occur within a period of no more than 120 days,
then the Adjustment Factor shall be adjusted only once on account of such
issuances, with such adjustment to occur upon the final such issuance and to
give effect to all such issuances as if they occurred on the date of the final
such issuance.

                           b. ADJUSTMENT FOR STOCK SPLITS AND COMBINATIONS. If
the Corporation shall at any time or from time to time after the Original Issue
Date effect a subdivision of the outstanding Common Stock, the Adjustment
Factors then in effect immediately before that subdivision shall be
proportionately decreased. If the Corporation shall at any time or from time to
time after the Original Issue Date combine the outstanding shares of Common
Stock, the Adjustment Factors then in effect immediately before the combination
shall be proportionately increased. Any adjustment under this paragraph shall
become effective at the close of business on the date the subdivision or
combination becomes effective.

                           c. ADJUSTMENT FOR CERTAIN DIVIDENDS AND
DISTRIBUTIONS. In the event the Corporation at any time, or from time to time
after the Original Issue Date shall make or issue, or fix a record date for the
determination of holders of Common Stock entitled to 


                                      12.


<PAGE>

receive, a dividend or other distribution payable in additional shares of 
Common Stock, then and in each such event the Adjustment Factors then in 
effect shall be decreased as of the time of such issuance or, in the event 
such a record date shall have been fixed, as of the close of business on such 
record date, by multiplying the Adjustment Factors then in effect by a 
fraction:

                                    (i) the numerator of which shall be the
total number of shares of Common Stock issued and outstanding immediately prior
to the time of such issuance or the close of business on such record date, and

                                    (ii) the denominator of which shall be the
total number of shares of Common Stock issued and outstanding immediately prior
to the time of such issuance or the close of business on such record date plus
the number of shares of Common Stock issuable in payment of such dividend or
distribution;

provided, however if such record date shall have been fixed and such dividend is
not fully paid or if such distribution is not fully made on the date fixed
therefor, the Adjustment Factor shall be recomputed accordingly as of the close
of business on such record date and thereafter the Adjustment Factor shall be
adjusted pursuant to this paragraph as of the time of actual payment of such
dividends or distributions.

                           d. ADJUSTMENTS FOR OTHER DIVIDENDS AND DISTRIBUTIONS.
In the event the Corporation at any time or from time to time after the Original
Issue Date for the Series Preferred Stock shall make or issue, or fix a record
date for the determination of holders of Common Stock entitled to receive a
dividend or other distribution payable in securities of the Corporation other
than shares of Common Stock, then and in each such event provision shall be made
so that the holders of the Series Preferred Stock shall receive upon the
issuance of the Special Dividend in addition to the number of shares of Series
Preferred Stock receivable thereupon, the amount of securities of the
Corporation that they would have received had the issuance of the Special
Dividend occurred and the preferences of the Series Preferred Stock expired or
converted, as the case may be, pursuant to Section C.5. herein immediately
before the record date of such event and had they thereafter, during the period
from the date of such event to and including the date of issue of the Special
Dividend, retained such securities receivable by them as aforesaid during such
period, giving application to all adjustments called for during such period
under this paragraph with respect to the rights of the holders of the Series
Preferred Stock.

                           e. ADJUSTMENT FOR RECLASSIFICATION, EXCHANGE, OR
SUBSTITUTION. If the Common Stock shall be changed into the same or a different
number of shares of any class or classes of stock, whether by capital
reorganization, reclassification, or otherwise (other than a subdivision or
combination of shares or stock dividend provided for above, or a reorganization,
merger, consolidation, or sale of assets provided for below), then and in each
such event upon the expiry of the preferences or conversion, as the case may be,
of the Series Preferred Stock pursuant to Section C.5. herein each such share of
Series Preferred Stock shall have the rights, privileges and obligations of the
kind and amount of shares of stock and other securities and property receivable
upon such reorganization, reclassification, or other change, by holders of the
number of shares of Common Stock into which such shares of Series Preferred
Stock have been transformed had the issue of the Special Dividend and the expiry
of the preferences or conversion, as the case may be, of the Series Preferred
Stock pursuant to Section C.5. herein 


                                      13.


<PAGE>

occurred immediately prior to such reorganization, reclassification, or 
change, all subject to further adjustment as provided herein.

                           f. ADJUSTMENT FOR MERGER OR REORGANIZATION, ETC. In
case of any consolidation or merger of the Corporation with or into another
corporation or the sale of all or substantially all of the assets of the
Corporation to another corporation (other than a consolidation, merger or sale
which is covered by Subsection 2.c.), each holder of shares of Series Preferred
Stock will be entitled to receive in the merger, consolidation or sale the kind
and amount of shares of stock or other securities to which such holder would be
entitled if (x), with respect to the holders of Series A, Series B, Series D and
Series E Preferred Stock, the Special Dividend had been declared and paid
immediately before the effective date of such merger, consolidation or sale; and
(y) such holder was, on the effective date of such merger, consolidation or
sale, the holder of that number of shares of Common Stock into which the
holder's shares of Series Preferred Stock are convertible or the number of
shares of Common Stock equal to the sum of the number of its Series Preferred
Stock and the number of shares of Series Preferred Stock it would have received
pursuant to the Special Dividend, as the case may be.

                           g. NO IMPAIRMENT. The Corporation will not, by
amendment of this Certificate of Incorporation or through any reorganization,
transfer of assets, consolidation, merger, dissolution, issue or sale of
securities or any other voluntary action, avoid or seek to avoid the observance
or performance of any of the terms to be observed or performed hereunder by the
Corporation, but will at all times in good faith assist in the carrying out of
all the provisions of this Section 4 and in the taking of all such action as may
be necessary or appropriate in order to protect the rights of the holders of the
Series Preferred Stock against impairment.

                           h. CERTIFICATE AS TO ADJUSTMENTS. Upon the occurrence
of each adjustment or readjustment of the Adjustment Factor pursuant to this
Section 4, the Corporation at its expense shall promptly compute such adjustment
or readjustment in accordance with the terms hereof and furnish to each holder
of Series Preferred Stock a certificate setting forth such adjustment or
readjustment and showing in detail the facts upon which such adjustment or
readjustment is based. The Corporation shall, upon the written request at any
time of any holder of Series Preferred Stock, furnish or cause to be furnished
to such holder a similar certificate setting forth (i) such adjustments and
readjustments, (ii) the applicable Adjustment Factor then in effect, and (iii)
the number of shares of Series Preferred Stock and the amount, if any, of other
property which then would be received upon the declaration and payment of the
Special Dividend.

                           i. NOTICE OF RECORD DATE. In the event:

                                    (i) that the Corporation declares a dividend
(or any other distribution) on its Common Stock payable in Common Stock or other
securities of the Corporation;

                                    (ii) that the Corporation subdivides or
combines its outstanding shares of Common Stock;


                                      14.


<PAGE>

                                    (iii) of any reclassification of the Common
Stock of the Corporation (other than a subdivision or combination of its
outstanding shares of Common Stock or a stock dividend or stock distribution
thereon), or of any consolidation or merger of the Corporation into or with
another corporation, or of the sale of all or substantially all of the assets of
the Corporation; or

                                    (iv) of the involuntary or voluntary
dissolution, liquidation or winding up of the Corporation;

then the Corporation shall cause to be filed at its principal office or at the
office of the transfer agent of the Series Preferred Stock, and shall cause to
be mailed to the holders of the Series Preferred Stock at their last addresses
as shown on the records of the Corporation or such transfer agent, at least ten
days prior to the date specified in (a) below or twenty days before the date
specified in (b) below, a notice stating

                                             (a) the record date of such
dividend, distribution, subdivision or combination, or, if a record is not to be
taken, the date as of which the holders of Common Stock of record to be entitled
to such dividend, distribution, subdivision or combination are to be determined,
or

                                             (b) the date on which such
reclassification, consolidation, merger, sale, dissolution, liquidation or
winding up is expected to become effective, and the date as of which it is
expected that holders of Common Stock of record shall be entitled to exchange
their shares of Common Stock for securities or other property deliverable upon
such reclassification, consolidation, merger, sale, dissolution or winding up.

                  5. EXPIRY OF PREFERENCES OF SERIES A, B, D AND E PREFERRED
STOCK; CONVERSION OF SERIES C PREFERRED STOCK.

                           a. EXPIRY OF PREFERENCES OF SERIES A AND B PREFERRED
STOCK. Upon the closing of the sale of shares of Common Stock, at a price of at
least $7.50 per share (subject to appropriate adjustment for stock splits, stock
dividends, combinations and other similar recapitalizations affecting such
shares), in a public offering pursuant to an effective registration statement
under the Securities Act of 1933, as amended (the "Act"), resulting in at least
$7,500,000 of gross proceeds to the Corporation, (i) each and every preference
or senior right of the Series A and B Preferred Stock relative to the Common
Stock, including without limitation as set forth in Sections C.1, C.2, C.3 and
C.4 herein, shall expire and be of no further force or effect and (ii) the
Corporation may reclassify all shares of Series A and Series B Preferred Stock
having rights and privileges on a parity with the Common Stock as Common Stock
whereupon the number of authorized shares of Preferred Stock shall be
automatically reduced by a number of shares of Preferred Stock that had been
designated as Series A and B Preferred Stock, and all provisions included under
the caption "Series Preferred Stock", and all references to the Series Preferred
Stock, shall be of no further force or effect with respect to the Series A and B
Preferred Stock.

                                    (i) All holders of record of shares of
Series A and B Preferred Stock shall be given written notice of the effective
date or the expiry of the preferences of the 


                                      15.


<PAGE>

Series A and B Preferred Stock, no less than 60 days in advance thereof. Such 
notice shall be sent by first class or registered mail, postage prepaid, to 
each record holder of Series A and B Preferred Stock at such holder's address 
last shown on the records of the transfer agent for the Series A and B 
Preferred Stock (or the records of the Corporation, if it serves as its own 
transfer agent). The notice shall include a calculation of the Special 
Dividend in detail sufficient to permit the holders of Series A and B 
Preferred Stock to verify the conformity of the amount of the dividend to the 
terms hereof. Within 30 days of receipt of such notice, the Board of 
Directors shall forward to each holder of Series A and B Preferred Stock a 
certificate for the number of shares of Series A and B Preferred Stock to 
which such holder is entitled pursuant to the Special Dividend. Upon receipt 
of such shares, each holder of shares of Series A and B Preferred Stock may 
surrender his or its certificate or certificates for all such shares to the 
Corporation at the place designated in such notice, and shall thereafter at 
the option of such holder, receive either (i) the certificate(s) for such 
shares duly endorsed to evidence the expiry of any preference rights, or (ii) 
certificates for a comparable number of shares of Common Stock. After the 
expiry of the preferences of Series A and B Preferred Stock the Corporation 
may demand, in connection with the reclassification of such shares pursuant 
to Section C.5.a. herein, that all holders of certificates for Series A and B 
Preferred Stock so expired surrender to the Corporation their certificate or 
certificates for Series A and B Preferred Stock, the Corporation shall cause 
to be issued and delivered to such holder, a certificate or certificates for 
a comparable number of full shares of Common Stock.

                                    (ii) All certificates evidencing shares of
Series A and B Preferred Stock, from and after the expiry of the preferences of
the Series A and B Preferred Stock, shall be deemed to represent shares of
Common Stock for all purposes, notwithstanding the failure of the holder or
holders thereof to surrender such certificates on or prior to such date. The
Corporation may thereafter take such appropriate action (without the need for
stockholder action) as may be necessary to reduce the authorized Series A and B
Preferred Stock accordingly.

                           b. CONVERSION OF SERIES C PREFERRED STOCK. The
holders of the Series C Preferred Stock shall have conversion rights as follows
(the "Conversion Rights"):

                                    (i) OPTIONAL CONVERSION. Each share of
Series C Preferred Stock shall be convertible at the option of the holder
thereof, without payment of additional consideration at any time, at the office
of the Corporation or any transfer agent for the Series C Preferred Stock, into
such number of fully paid and nonassessable shares of Common Stock as is
determined by dividing $6.00 by the Series C Adjustment Factor then in effect
for such share; PROVIDED, HOWEVER, that the Adjustment Factor for the Series C
Preferred Stock shall be subject to adjustment as set forth in subsection C.4.

                                    (ii) AUTOMATIC CONVERSION. Each share of
Series C Preferred Stock shall automatically be converted into the number of
shares of Common Stock into which such share of Series C Preferred Stock is then
convertible pursuant to Section 5.b.(i): (1) in the event that the holders of
not less than sixty-seven percent (67%) of the outstanding Series C Preferred
Stock consent to such conversion, or (2) upon the closing of a firm commitment
underwritten public offering pursuant to an effective registration statement
under the Act, covering the offer and sale by the Corporation of Common Stock to
the public at an aggregate 


                                      16.


<PAGE>

offering price of not less than $15,000,000 (prior to underwriters' discounts 
and expenses), and at a public offering price not less than $12.00 per share, 
subject to adjustment for stock splits, stock dividends, reorganizations and 
the like with respect to the Common Stock.

                                    (iii) MECHANICS OF CONVERSION. No fractional
shares of Common Stock shall be issued upon conversion of the Series C Preferred
Stock. In lieu of any fractional share, the Corporation shall pay cash equal to
such fraction multiplied by the then current fair market value of a share of
Common Stock as determined in good faith by the Board of Directors of the
Corporation. Before any holder of Series C Preferred Stock shall be entitled to
convert the same into shares of Common Stock, it shall surrender the certificate
or certificates therefor, duly endorsed, at the office of the Corporation or of
any transfer agent for the Series C Preferred Stock, and shall give written
notice to the Corporation at such office that it elects to convert the same
(except that no such written notice of election to convert shall be necessary in
the event of an automatic conversion pursuant to Section 5.b.(ii)). The
Corporation shall, as soon as practicable thereafter, issue and deliver at such
office to such holder of Series C Preferred Stock a certificate or certificates,
registered in such names as specified by the holder, for the number of shares of
Common Stock to which such holder shall be entitled as aforesaid, and a check
payable to the holder in the amount of any amounts payable for fractional shares
and any declared and unpaid dividends on the converted Series C Preferred Stock.
Such conversion shall be deemed to have been made immediately prior to the close
of business on the date of such surrender of the shares of the Series C
Preferred Stock to be converted, and the person or persons entitled to receive
the shares of Common Stock issuable upon such conversion shall be treated for
all purposes as the record holder or holders of such shares of Common Stock on
such date (except that in the event of an automatic conversion pursuant to
Section 5.b.(ii)(1), such conversion shall be deemed to have been made at the
close of business on the date fixed in the vote approving such automatic
conversion and in the event of automatic conversion pursuant to Section
5.b.(ii)(2), such conversion shall be deemed to have been made immediately prior
to the closing of the offering referred to in Section 5.b.(ii)(2). If the
conversion is in connection with an underwritten offer of securities registered
pursuant to the Act, the conversion may, at the option of any holder tendering
Series C Preferred Stock for conversion, be conditioned upon the closing with
the underwriter of the sale of securities pursuant to such offering, in which
event the person(s) entitled to receive the Common Stock issuable upon such
conversion of Series C Preferred Stock shall not be deemed to have converted
such Series C Preferred Stock until immediately prior to the closing of such
sale of securities. If such conversion is in connection with a merger,
consolidation or sale of assets which would be treated as a liquidation,
dissolution or winding up of the Corporation in accordance with and for purposes
of Section C.2., the conversion may, at the option of the holder tendering
Series C Preferred Stock for conversion, be conditioned upon the consummation of
such transaction, in which event the person(s) entitled to receive the Common
Stock issuable upon such conversion of Series C Preferred Stock shall not be
deemed to have converted such Series C Preferred Stock until immediately prior
to the consummation of such transaction.


                                      17.


<PAGE>

                                    (iv) RESERVATION OF STOCK ISSUABLE UPON
CONVERSION. This Corporation shall at all times reserve and keep available out
of its authorized but unissued shares of Common Stock solely for the purpose of
effecting the conversion of the shares of Series C Preferred Stock such number
of its shares of Common Stock as shall from time to time be sufficient to effect
the conversion of all outstanding shares of Series C Preferred Stock; and if at
any time the number of authorized but unissued shares of Common Stock shall not
be sufficient to effect the conversion of all then outstanding shares of Series
C Preferred Stock in addition to such other remedies as shall be available to
the holder of such Series C Preferred Stock, this Corporation will take such
corporate action as may, in the opinion of its counsel, be necessary to increase
its authorized but unissued shares of Common Stock to such number of shares as
shall be sufficient for such purposes.

                           c. EXPIRY OF PREFERENCES OF SERIES D PREFERRED STOCK.
Upon the closing of the sale of shares of Common Stock, at a price of at least
$12.00 per share (subject to appropriate adjustment for stock splits, stock
dividends, combinations and other similar recapitalizations affecting such
shares), in a public offering pursuant to an effective registration statement
under the Act, resulting in at least $15,000,000 of gross proceeds to the
Corporation, (i) each and every preference or senior right of the Series D
Preferred Stock relative to the Common Stock, including without limitation as
set forth in Sections C.1, C.2, C.3 and C.4 herein, shall expire and be of no
further force or effect and (ii) the Corporation may reclassify all shares of
Series D Preferred Stock having rights and privileges on a parity with the
Common Stock as Common Stock whereupon the number of authorized shares of
Preferred Stock shall be automatically reduced by a number of shares of
Preferred Stock that had been designated as Series D Preferred Stock, and all
provisions included under the caption "Series Preferred Stock", and all
references to the Series Preferred Stock, shall be of no further force or effect
with respect to the Series D Preferred Stock.

                                    (i) All holders of record of shares of
Series D Preferred Stock shall be given written notice of the effective date or
the expiry of the preferences of the Series D Preferred Stock, no less than 60
days in advance thereof. Such notice shall be sent by first class or registered
mail, postage prepaid, to each record holder of Series D Preferred Stock at such
holder's address last shown on the records of the transfer agent for the Series
D Preferred Stock (or the records of the Corporation, if it serves as its own
transfer agent). The notice shall include a calculation of the Special Dividend
in detail sufficient to permit the holders of Series D Preferred Stock to verify
the conformity of the amount of the dividend to the terms hereof. Within 30 days
of receipt of such notice, the Board of Directors shall forward to each holder
of Series D Preferred Stock a certificate for the number of shares of Series D
Preferred Stock to which such holder is entitled pursuant to the Special
Dividend. Upon receipt of such shares, each holder of shares of Series D
Preferred Stock may surrender his or its certificate or certificates for all
such shares to the Corporation at the place designated in such notice, and shall
thereafter at the option of such holder, receive either (i) the certificate(s)
for such shares duly endorsed to evidence the expiry of any preference rights,
or (ii) certificates for a comparable number of shares of Common Stock. After
the expiry of the preferences of Series D Preferred Stock the Corporation may
demand, in connection with the reclassification of such shares pursuant to
Section C.5.c. herein, that all holders of certificates for Series D Preferred
Stock so expired surrender to the Corporation their certificate or certificates
for Series D Preferred Stock, 


                                      18.


<PAGE>

the Corporation shall cause to be issued and delivered to such holder, a 
certificate or certificates for a comparable number of full shares of Common 
Stock.

                                    (ii) All certificates evidencing shares of
Series D Preferred Stock, from and after the expiry of the preferences of the
Series D Preferred Stock, shall be deemed to represent shares of Common Stock
for all purposes, notwithstanding the failure of the holder or holders thereof
to surrender such certificates on or prior to such date. The Corporation may
thereafter take such appropriate action (without the need for stockholder
action) as may be necessary to reduce the authorized Series D Preferred Stock
accordingly.

                           d. EXPIRY OF PREFERENCES OF SERIES E PREFERRED STOCK.
Upon the closing of the sale of shares of Common Stock, at a price of at least
$15.00 per share (subject to appropriate adjustment for stock splits, stock
dividends, combinations and other similar recapitalizations affecting such
shares), in a public offering pursuant to an effective registration statement
under the Act, resulting in at least $20,000,000 of gross proceeds to the
Corporation, (i) each and every preference or senior right of the Series E
Preferred Stock relative to the Common Stock, including without limitation as
set forth in Sections C.1, C.2, C.3 and C.4 herein, shall expire and be of no
further force or effect and (ii) the Corporation may reclassify all shares of
Series E Preferred Stock having rights and privileges on a parity with the
Common Stock as Common Stock whereupon the number of authorized shares of
Preferred Stock shall be automatically reduced by a number of shares of
Preferred Stock that had been designated as Series E Preferred Stock, and all
provisions included under the caption "Series Preferred Stock", and all
references to the Series Preferred Stock, shall be of no further force or effect
with respect to the Series E Preferred Stock.

                                    (i) All holders of record of shares of
Series E Preferred Stock shall be given written notice of the effective date or
the expiry of the preferences of the Series E Preferred Stock, no less than 60
days in advance thereof. Such notice shall be sent by first class or registered
mail, postage prepaid, to each record holder of Series E Preferred Stock at such
holder's address last shown on the records of the transfer agent for the Series
E Preferred Stock (or the records of the Corporation, if it serves as its own
transfer agent). The notice shall include a calculation of the Special Dividend
in detail sufficient to permit the holders of Series E Preferred Stock to verify
the conformity of the amount of the dividend to the terms hereof. Within 30 days
of receipt of such notice, the Board of Directors shall forward to each holder
of Series E Preferred Stock a certificate for the number of shares of Series E
Preferred Stock to which such holder is entitled pursuant to the Special
Dividend. Upon receipt of such shares, each holder of shares of Series E
Preferred Stock may surrender his or its certificate or certificates for all
such shares to the Corporation at the place designated in such notice, and shall
thereafter at the option of such holder, receive either (i) the certificate(s)
for such shares duly endorsed to evidence the expiry of any preference rights,
or (ii) certificates for a comparable number of shares of Common Stock. After
the expiry of the preferences of Series E Preferred Stock the Corporation may
demand, in connection with the reclassification of such shares pursuant to
Section C.5.c. herein, that all holders of certificates for Series E Preferred
Stock so expired surrender to the Corporation their certificate or certificates
for Series E Preferred Stock, the Corporation shall cause to be issued and
delivered to such holder, a certificate or certificates for a comparable number
of full shares of Common Stock.


                                     19.


<PAGE>

                                    (ii) All certificates evidencing shares of
Series E Preferred Stock, from and after the expiry of the preferences of the
Series E Preferred Stock, shall be deemed to represent shares of Common Stock
for all purposes, notwithstanding the failure of the holder or holders thereof
to surrender such certificates on or prior to such date. The Corporation may
thereafter take such appropriate action (without the need for stockholder
action) as may be necessary to reduce the authorized Series E Preferred Stock
accordingly.

                                       V.

         In furtherance of and not in limitation of powers conferred by statute,
it is further provided:

                           1. Election of directors need not be by written
                           ballot.

                           2. The Board of Directors is expressly authorized to
                           adopt, amend or repeal the By-Laws of the
                           Corporation.

                                      VI.

         Except to the extent that the General Corporation Law of Delaware
prohibits the elimination or limitation of liability of directors for breaches
of fiduciary duty, no director of the Corporation shall be personally liable to
the Corporation or its stockholders for monetary damages for any breach of
fiduciary duty as a director, notwithstanding any provision of law imposing such
liability. No amendment to or repeal of this provision shall apply to or have
any effect on the liability or alleged liability of any director of the
Corporation for or with respect to any acts or omissions of such director
occurring prior to such amendment.

                                      VII.

         A. ACTIONS, SUITS AND PROCEEDINGS OTHER THAN BY OR IN THE RIGHT OF 
THE CORPORATION. The Corporation shall indemnify each person who was or is a 
party or is threatened to be made a party to any threatened, pending or 
completed action, suit or proceeding, whether civil, criminal, administrative 
or investigative (other than an action by or in the right of the 
Corporation), by reason of the fact that he is or was, or has agreed to 
become, a director or officer of the Corporation, or is or was serving, or 
has agreed to serve, at the request of the Corporation, as a director, 
officer or trustee of, or in a similar capacity with, another corporation, 
partnership, joint venture, trust or other enterprise (including any employee 
benefit plan) (all such persons being referred to hereafter as an 
"Indemnitee"), or by reason of any action alleged to have been taken or 
omitted in such capacity, against all expenses (including attorneys' fees), 
judgments, fines and amounts paid in settlement actually and reasonably 
incurred by him or on his behalf in connection with such action, suit or 
proceeding and any appeal therefrom, if he acted in good faith and in a 
manner he reasonably believed to be in, or not opposed to, the best interests 
of the Corporation, and, with respect to any criminal action or proceeding, 
had no reasonable cause to believe his conduct was unlawful. The termination 
of any action, suit or proceeding by judgment, order, settlement, conviction 
or upon a plea of NOLO CONTENDERE or its equivalent, shall not, of itself, 
create a presumption that the person did not act in good faith and in a 
manner which he reasonably believed to be in, or not opposed to, the best 
interests of the Corporation, and, with respect to any criminal action or 
proceeding, had reasonable cause to 

                                     20.


<PAGE>

believe that his conduct was unlawful. Notwithstanding anything to the 
contrary in this Article, except as set forth in Section G below, the 
Corporation shall not indemnify an Indemnitee seeking indemnification in 
connection with a proceeding (or part thereof) initiated by the Indemnitee 
unless the initiation thereof was approved by the Board of Directors of the 
Corporation. Notwithstanding anything to the contrary in this Article, the 
Corporation shall not indemnify an Indemnitee to the extent such Indemnitee 
is reimbursed from the proceeds of insurance, and in the event the 
Corporation makes any indemnification payments to an Indemnitee and such 
Indemnitee is subsequently reimbursed from the proceeds of insurance, such 
Indemnitee shall promptly refund such indemnification payments to the 
Corporation to the extent of such insurance reimbursement.

         B. ACTIONS OR SUITS BY OR IN THE RIGHT OF THE CORPORATION. The
Corporation shall indemnify any Indemnitee who was or is a party or is
threatened to be made a party to any threatened, pending or completed action or
suit by or in the right of the Corporation to procure a judgment in its favor by
reason of the fact that he is or was, or has agreed to become, a director or
officer of the Corporation, or is or was serving, or has agreed to serve, at the
request of the Corporation, as a director, officer or trustee of, or in a
similar capacity with, another corporation, partnership, joint venture, trust or
other enterprise (including any employee benefit plan), or by reason of any
action alleged to have been taken or omitted in such capacity, against all
expenses (including attorneys' fees) and, to the extent permitted by law,
amounts paid in settlement actually and reasonably incurred by him or on his
behalf in connection with such action, suit or proceeding and any appeal
therefrom, if he acted in good faith and in a manner he reasonably believed to
be in, or not opposed to, the best interests of the Corporation, except that no
indemnification shall be made in respect of any claim, issue or matter as to
which such person shall have been adjudged to be liable to the Corporation
unless and only to the extent that the Court of Chancery of Delaware shall
determine upon application that, despite the adjudication of such liability but
in view of all the circumstances of the case, such person is fairly and
reasonably entitled to indemnity for such expenses (including attorneys' fees)
which the Court of Chancery of Delaware shall deem proper.

         C. INDEMNIFICATION FOR EXPENSES OF SUCCESSFUL PARTY. Notwithstanding
the other provisions of this Article, to the extent that an Indemnitee has been
successful, on the merits or otherwise, in defense of any action, suit or
proceeding referred to in Sections A and B of this Article, or in defense of any
claim, issue or matter therein, or on appeal from any such action, suit or
proceeding, he shall be indemnified against all expenses (including attorneys'
fees) actually and reasonably incurred by him or on his behalf in connection
therewith. Without limiting the foregoing, if any action, suit or proceeding is
disposed of, on the merits or otherwise (including a disposition without
prejudice), without (i) the disposition being adverse to the Indemnitee, (ii) an
adjudication that the Indemnitee was liable to the Corporation, (iii) a plea of
guilty or NOLO CONTENDERE by the Indemnitee, (iv) an adjudication that the
Indemnitee did not act in good faith and in a manner he reasonably believed to
be in or not opposed to the best interests of the Corporation, and (v) with
respect to any criminal proceeding, an adjudication that the Indemnitee had
reasonable cause to believe his conduct was unlawful, the Indemnitee shall be
considered for the purposes hereof to have been wholly successful with respect
thereto.

         D. NOTIFICATION AND DEFENSE OF CLAIM. As a condition precedent to his
right to be indemnified, the Indemnitee must notify the Corporation in writing
as soon as practicable of any 


                                      21.


<PAGE>

action, suit, proceeding or investigation involving him for which indemnity 
will or could be sought. With respect to any action, suit, proceeding or 
investigation of which the Corporation is so notified, the Corporation will 
be entitled to participate therein at its own expense and/or to assume the 
defense thereof at its own expense, with legal counsel reasonably acceptable 
to the Indemnitee. After notice from the Corporation to the Indemnitee of its 
election so to assume such defense, the Corporation shall not be liable to 
the Indemnitee for any legal or other expenses subsequently incurred by the 
Indemnitee in connection with such claim, other than as provided below in 
this Section D. The Indemnitee shall have the right to employ his own counsel 
in connection with such claim, but the fees and expenses of such counsel 
incurred after notice from the Corporation of its assumption of the defense 
thereof shall be at the expense of the Indemnitee unless (i) the employment 
of counsel by the Indemnitee has been authorized by the Corporation, (ii) 
counsel to the Indemnitee shall have reasonably concluded that there may be a 
conflict of interest or position on any significant issue between the 
Corporation and the Indemnitee in the conduct of the defense of such action 
or (iii) the Corporation shall not in fact have employed counsel to assume 
the defense of such action, in each of which cases the fees and expenses of 
counsel for the Indemnitee shall be at the expense of the Corporation, except 
as otherwise expressly provided by this Article. The Corporation shall not be 
entitled, without the consent of the Indemnitee, to assume the defense of any 
claim brought by or in the right of the Corporation or as to which counsel 
for the Indemnitee shall have reasonably made the conclusion provided for in 
clause (ii) above.

         E. ADVANCE OF EXPENSES. Subject to the provisions of Section F below,
in the event that the Corporation does not assume the defense pursuant to
Section D of this Article of any action, suit, proceeding or investigation of
which the Corporation receives notice under this Article, any expenses
(including attorneys' fees ) incurred by an Indemnitee in defending a civil or
criminal action, suit, proceeding or investigation or any appeal therefrom shall
be paid by the Corporation in advance of the final disposition of such matter;
PROVIDED, HOWEVER, that the payment of such expenses incurred by an Indemnitee
in advance of the final disposition of such matter shall be made only upon
receipt of an undertaking by or on behalf of the Indemnitee to repay all amounts
so advanced in the event that it shall ultimately be determined that the
Indemnitee is not entitled to be indemnified by the Corporation as authorized in
this Article. Such undertaking shall be accepted without reference to the
financial ability of the Indemnitee to make such repayment.

         F. PROCEDURE FOR INDEMNIFICATION. In order to obtain indemnification or
advancement of expenses pursuant to Section A, B, C or E of this Article, the
Indemnitee shall submit to the Corporation a written request, including in such
request such documentation and information as is reasonably available to the
Indemnitee and is reasonably necessary to determine whether and to what extent
the Indemnitee is entitled to indemnification or advancement of expenses. Any
such indemnification or advancement of expenses shall be made promptly, and in
any event within 60 days after receipt by the Corporation of the written request
of the Indemnitee, unless with respect to requests under Section A, B or E the
Corporation determines within such 60-day period that the Indemnitee did not
meet the applicable standard of conduct set forth in Section A or B, as the case
may be. Such determination shall be made in each instance by (a) a majority vote
of the directors of the Corporation consisting of persons who are not at the
time parties to the action, suit or proceeding in questions ("disinterested
directors"), whether or not a quorum, (b) a majority vote of a quorum of the
outstanding shares of stock of all 


                                      22.


<PAGE>

classes entitled to vote for directors, voting as a single class, which 
quorum shall consist of stockholders who are not at that time parties to the 
action, suit or proceeding in question, (c) independent legal counsel (who 
may, to the extent permitted by law, be regular counsel to the Corporation), 
or (d) a court of competent jurisdiction.

         G. REMEDIES. The right to indemnification or advances as granted by
this Article shall be enforceable by the Indemnitee in any court of competent
jurisdiction if the Corporation denies such request, in whole or in part, or if
no disposition thereof is made within the 60-day period, referred to above in
Section F. Unless otherwise required by law, the burden of proving that the
Indemnitee is not entitled to indemnification or advancement of expenses under
this Article shall be on the Corporation. Neither the failure of the Corporation
to have made a determination prior to the commencement of such action that
indemnification is proper in the circumstances because the Indemnitee has met
the applicable standard of conduct, nor an actual determination by the
Corporation pursuant to Section F that the Indemnitee has not met such
applicable standard of conduct, shall be a defense to the action or create a
presumption that the Indemnitee has not met the applicable standard of conduct.
The Indemnitee's expenses (including attorneys' fees) incurred in connection
with successfully establishing his right to indemnification, in whole or in
part, in any such proceeding shall also be indemnified by the Corporation.

         H. SUBSEQUENT AMENDMENT. No amendment, termination or repeal of this
Article or the relevant provisions of the General Corporation Law of Delaware or
any other applicable laws shall affect or diminish in any way the rights of any
Indemnitee to indemnification under the provisions hereof with respect to any
action, suit, proceeding or investigation arising out of or relating to any
actions, transactions or facts occurring prior to the final adoption of such
amendment, termination or repeal.

         I. OTHER RIGHTS. The indemnification and advancement of expenses
provided by this Article shall not be deemed exclusive of any other rights to
which an Indemnitee seeking indemnification or advancement of expenses may be
entitled under any law (common or statutory), agreement or vote of stockholders
or disinterested directors or otherwise, both as to action in his official
capacity and as to action in any other capacity while holding office for the
Corporation, and shall continue as to an Indemnitee who has ceased to be a
director or officer, and shall inure to the benefit of the estate, heirs,
executors and administrators of the Indemnitee. Nothing contained in this
Article shall be deemed to prohibit, and the Corporation is specifically
authorized to enter into, agreements with officers and directors providing
indemnification rights and procedures different from those set forth in this
Article. In addition, the Corporation may, to the extent authorized from time to
time by its Board of Directors, grant indemnification rights to other employees
or agents of the Corporation or other persons serving the Corporation and such
rights may be equivalent to, or greater or less than, those set forth in this
Article.

         J. PARTIAL INDEMNIFICATION. If an Indemnitee is entitled under any
provision of this Article to indemnification by the Corporation for some or a
portion of the expenses (including attorneys' fees), judgments, fines or amounts
paid in settlement actually and reasonably incurred by him or on his behalf in
connection with any action, suit, proceeding or investigation and any appeal
therefrom but not, however, for the total amount thereof, the Corporation shall


                                     23.


<PAGE>

nevertheless indemnify the Indemnitee for the portion of such expenses
(including attorneys' fees), judgments, fines or amounts paid in settlement to
which the Indemnitee is entitled.

         K. INSURANCE. The Corporation may purchase and maintain insurance, at
its expense, to protect itself and any director, officer, employee or agent of
the Corporation or another corporation, partnership, joint venture, trust or
other enterprise (including any employee benefit plan) against any expense,
liability or loss incurred by him in any such capacity, or arising out of his
status as such, whether or not the Corporation would have the power to indemnify
such person against such expense, liability or loss under the General
Corporation Law of Delaware.

         L. MERGER OR CONSOLIDATION. If the Corporation is merged into or
consolidated with another corporation and the Corporation is not the surviving
corporation, the surviving corporation shall assume the obligations of the
Corporation under this Article with respect to any action, suit, proceeding or
investigation arising out of or relating to any actions, transactions or facts
occurring prior to the date of such merger or consolidation.

         M. SAVINGS CLAUSE. If this Article or any portion hereof shall be
invalidated on any ground by any court of competent jurisdiction, then the
Corporation shall nevertheless indemnify each Indemnitee as to any expenses
(including attorneys' fees), judgments, fines and amounts paid in settlement in
connection with any action, suit, proceeding or investigation, whether civil,
criminal or administrative, including an action by or in the right of the
Corporation, to the fullest extent permitted by any applicable portion of this
Article that shall not have been invalidated and to the fullest extent permitted
by applicable law.

         N. DEFINITIONS. Terms used herein and defined in Section 145(h) and
Section 145(i) of the General Corporation Law of Delaware shall have the
respective meanings assigned to such terms in such Section 145(h) and Section
145(i).

         O. SUBSEQUENT LEGISLATION. If the General Corporation Law of Delaware
is amended after adoption of this Article to expand further the indemnification
permitted to Indemnitees, then the Corporation shall indemnify such persons to
the fullest extent permitted by the General Corporation Law of Delaware, as so
amended.

                                     VIII.

         The Corporation reserves the right to amend, alter, change or repeal
any provision contained in this Certificate of Incorporation, in the manner now
or hereafter prescribed by statute and this Certificate of Incorporation, and
all rights conferred upon stockholders herein are granted subject to this
reservation.


                                     24.




<PAGE>

                                                     [FORM OF POST-IPO CHARTER]


                              AMENDED AND RESTATED
                          CERTIFICATE OF INCORPORATION
                                       OF
                           ACADIA PHARMACEUTICALS INC.


         ACADIA Pharmaceuticals Inc., a corporation organized and existing under
and by virtue of the General Corporation Law of the State of Delaware (the
"Corporation"), does hereby certify as follows:

                  FIRST: The name of the Corporation is: ACADIA Pharmaceuticals
Inc.

                  SECOND: The Corporation's original Certificate of
Incorporation was filed with the Secretary of State on January 16, 1997 under
the name Receptor Technologies, Inc.

                  THIRD: The Amended and Restated Certificate of Incorporation
of this Corporation, in the form attached hereto as Exhibit A, has been duly
adopted by the Board of Directors and stockholders in accordance with the
provisions of Sections 228, 242 and 245 of the General Corporation Law of the
State of Delaware. At least two-thirds of each of the outstanding Series A,
Series B, Series C, Series D and Series E Preferred Stock of the Corporation,
each voting as a separate class, at least two-thirds of the outstanding Series
A, Series B, Series D and Series E Preferred Stock of the Corporation, voting as
a separate class, and at least 50% of the outstanding Common Stock and Series A,
Series B, Series
 C, Series D and Series E Preferred Stock of the Corporation,
voting as a separate class, approved this Restated Certificate of Incorporation
by written consent in accordance with Section 228 of the General Corporation Law
of the State of Delaware and written notice of such was given by the Corporation
in accordance with said Section 228.

                  FOURTH: The Amended and Restated Certificate of Incorporation
so adopted reads in full as set forth in Exhibit A attached hereto and is hereby
incorporated by reference.

                  IN WITNESS WHEREOF, ACADIA Pharmaceuticals Inc. has caused
this Amended and Restated Certificate of Incorporation to be signed by its Chief
Executive Officer this ____ day of ____________, 2001.

                                               ACADIA PHARMACEUTICALS INC.



                                               By:                              
                                                  ------------------------------
                                                     Uli Hacksell, Ph.D.,
                                                     Chief Executive Officer


                                       1.

<PAGE>


                                    EXHIBIT A


                              AMENDED AND RESTATED
                          CERTIFICATE OF INCORPORATION
                                       OF
                           ACADIA PHARMACEUTICALS INC.



                                       I.

         The name of this Corporation is ACADIA PHARMACEUTICALS INC.

                                       II.

         The address of its registered office in the State of Delaware is
Corporation Service Company, 1013 Centre Road, in the City of Wilmington, County
of New Castle. The name of its registered agent at such address is Corporation
Service Company.

                                      III.

         The nature of the business or purposes to be conducted or promoted by
the Corporation is as follows:

         To engage in any lawful act or activity for which corporations may be
organized under the General Corporation Law of Delaware (the "DGCL").

                                       IV.

         A. This Corporation is authorized to issue two classes of stock to be
designated, respectively, "Common Stock" and "Preferred Stock." The total number
of shares which the corporation is authorized to issue is Fifty-Five Million
(55,000,000) shares. Fifty Million (50,000,000) shares shall be Common Stock,
each having a par value of one-hundredth of one cent ($.0001). Five Million
(5,000,000) shares shall be Preferred Stock, each having a par value of
one-hundredth of one cent ($.0001).

         B. The Preferred Stock may be issued from time to time in one or more
series. The Board of Directors is hereby authorized, by filing a certificate
pursuant to the DGCL, to fix or alter from time to time the designation, powers,
preferences and rights of the shares of each such series and the qualifications,
limitations or restrictions of any wholly unissued series of Preferred Stock,
and to establish from time to time the number of shares constituting any such
series or any of them; and to increase or decrease the number of shares of any
series subsequent to the issuance of shares of that series, but not below the
number of shares of such series then outstanding. In case the number of shares
of any series shall be decreased in accordance with the foregoing sentence, the
shares constituting such decrease shall resume the status that they had prior to
the adoption of the resolution originally fixing the number of shares of such
series.


                                       1.

<PAGE>

         C. Each outstanding share of Common Stock shall entitle the holder
thereof to one vote on each matter properly submitted to the stockholders of the
Corporation for their vote; provided, however, that, except as otherwise
required by law, holders of Common Stock shall not be entitled to vote on any
amendment to this Certificate of Incorporation (including any certificate of
designation filed with respect to any series of Preferred Stock) that relates
solely to the terms of one or more outstanding series of Preferred Stock if the
holders of such affected series of Preferred Stock are entitled, either
separately or together as a class with the holders of one or more other series
of Preferred Stock, to vote thereon by law or pursuant to this Certificate of
Incorporation (including any certificate of designation filed with respect to
any series of Preferred Stock).

                                       V.

         For the management of the business and for the conduct of the affairs
of the Corporation, and in further definition, limitation and regulation of the
powers of the Corporation, of its directors and of its stockholders or any class
thereof, as the case may be, it is further provided that:

         A. BOARD OF DIRECTORS.

                  1. POWERS AND NUMBERS OF DIRECTORS. The management of the
business and the conduct of the affairs of the Corporation shall be vested in
its Board of Directors. The number of directors which shall constitute the whole
Board of Directors shall be fixed exclusively by one or more resolutions adopted
by the Board of Directors and not inconsistent with the Certificate of
Incorporation of the Corporation.

                  2. BOARD OF DIRECTORS. Subject to the rights of the holders of
any series of Preferred Stock to elect directors under specified circumstances,
following the closing of the initial public offering pursuant to an effective
registration statement under the Act, covering the offer and sale of Common
Stock to the public (the "Initial Public Offering"), the directors shall be
divided into three classes designated as Class I, Class II and Class III,
respectively. Directors shall be assigned to each class in accordance with a
resolution or resolutions adopted by the Board of Directors. At the first annual
meeting of stockholders following the closing of the Initial Public Offering,
the term of office of the Class I directors shall expire and Class I directors
shall be elected for a full term of three years. At the second annual meeting of
stockholders following the closing of the Initial Public Offering, the term of
office of the Class II directors shall expire and Class II directors shall be
elected for a full term of three years. At the third annual meeting of
stockholders following the closing of the Initial Public Offering, the term of
office of the Class III directors shall expire and Class III directors shall be
elected for a full term of three years. At each succeeding annual meeting of
stockholders, directors shall be elected for a full term of three years to
succeed the directors of the class whose terms expire at such annual meeting.

                  Notwithstanding the foregoing provisions of this section, each
director shall serve until his successor is duly elected and qualified or until
his death, resignation or removal. No decrease in the number of directors
constituting the Board of Directors shall shorten the term of any incumbent
director.


                                       2.

<PAGE>

                  3. REMOVAL OF DIRECTORS.

                           a. Subject to the rights of any series of Preferred
Stock to elect additional directors under specified circumstances, following the
closing of the Initial Public Offering, neither the Board of Directors nor any
individual director may be removed without cause.

                           b. Subject to any limitation imposed by law, any
individual director or directors may be removed with cause by the affirmative
vote of the holders of a majority of the voting power of all then-outstanding
shares of capital stock of the corporation entitled to vote generally at an
election of directors.

                  4. VACANCIES.

                           a. Subject to the rights of the holders of any series
of Preferred Stock, any vacancies on the Board of Directors resulting from
death, resignation, disqualification, removal or other causes and any newly
created directorships resulting from any increase in the number of directors,
shall, unless the Board of Directors determines by resolution that any such
vacancies or newly created directorships shall be filled by the stockholders,
except as otherwise provided by law, be filled only by the affirmative vote of a
majority of the directors then in office, even though less than a quorum of the
Board of Directors, and not by the stockholders. Any director elected in
accordance with the preceding sentence shall hold office for the remainder of
the full term of the director for which the vacancy was created or occurred and
until such director's successor shall have been elected and qualified.

                           b. If at the time of filling any vacancy or any newly
created directorship, the directors then in office shall constitute less than a
majority of the whole board (as constituted immediately prior to any such
increase), the Delaware Court of Chancery may, upon application of any
stockholder or stockholders holding at least ten percent (10%) of the total
number of the shares at the time outstanding having the right to vote for such
directors, summarily order an election to be held to fill any such vacancies or
newly created directorships, or to replace the directors chosen by the directors
then in offices as aforesaid, which election shall be governed by Section 211 of
the DGCL.

         B. BYLAWS.

                  1. Subject to paragraph (h) of Section 42 of the Bylaws and
subject to the rights of the holders of any series of Preferred Stock, the
Bylaws may be altered or amended or new Bylaws adopted by the affirmative vote
of at least sixty-six and two-thirds percent (66-2/3%) of the voting power of
all of the then-outstanding shares of the voting stock of the Corporation
entitled to vote. The Board of Directors shall also have the power to adopt,
amend, or repeal Bylaws.

                  2. The directors of the Corporation need not be elected by
written ballot unless the Bylaws so provide.

                  3. No action shall be taken by the stockholders of the
Corporation except at an annual or special meeting of stockholders called in
accordance with the Bylaws or by written 


                                       3.

<PAGE>

consent of stockholders in accordance with the Bylaws prior to the closing of
the Initial Public Offering and following the closing of the Initial Public
Offering no action shall be taken by the stockholders by written consent.

                  4. Advance notice of stockholder nominations for the election
of directors and of business to be brought by stockholders before any meeting of
the stockholders of the Corporation shall be given in the manner provided in the
Bylaws of the Corporation.

                                       VI.

         A. The liability of the directors for monetary damages shall be
eliminated to the fullest extent under applicable law.

         B. Any repeal or modification of this Article VI shall be prospective
and shall not affect the rights under this Article VI in effect at the time of
the alleged occurrence of any act or omission to act giving rise to liability or
indemnification.

                                      VII.

         A. The Corporation reserves the right to amend, alter, change or repeal
any provision contained in this Certificate of Incorporation, in the manner now
or hereafter prescribed by statute, except as provided in paragraph B. of this
Article VII, and all rights conferred upon the stockholders herein are granted
subject to this reservation.

         B. Notwithstanding any other provisions of this Certificate of
Incorporation or any provision of law which might otherwise permit a lesser vote
or no vote, but in addition to any affirmative vote of the holders of any
particular class or series of the Corporation required by law, this Certificate
of Incorporation or any certificate of designation filed with respect to a
series of Preferred Stock, the affirmative vote of the holders of at least
sixty-six and two-thirds percent (66-2/3%) of the voting power of all of the
then-outstanding shares of capital stock of the Corporation entitled to vote
generally in the election of directors, voting together as a single class, shall
be required to alter, amend or repeal Articles V, VI and VII.


                                       4.



<PAGE>


                                     BY-LAWS


                                       OF


                           ACADIA PHARMACEUTICALS INC.


                     (FORMERLY RECEPTOR TECHNOLOGIES, INC.)




<PAGE>

                                                        BY-LAWS

                                                   TABLE OF CONTENTS


<TABLE>
<CAPTION>

                                                                                                               PAGE
<S>                                                                                                            <C>
ARTICLE 1         STOCKHOLDERS....................................................................................1

         1.1      Place of Meetings...............................................................................1

         1.2      Annual Meeting..................................................................................1

         1.3      Special Meetings................................................................................1

         1.4      Notice of Meetings..............................................................................1

         1.5      Voting List.....................................................................................1

         1.6      Quorum..........................................................................................2

         1.7      Adjournments....................................................................................2

         1.8      Voting and Proxies..............................................................................2

         1.9      Action at Meeting...............................................................................2

         1.10     Action without Meeting..........................................................................2

ARTICLE 2         DIRECTORS.......................................................................................3

         2.1      General Powers..................................................................................3

         2.2      Number; Election and Qualification..............................................................3

         2.3      Enlargement of the Board........................................................................3

         2.4      Tenure..........................................................................................3

         2.5      Vacancies.......................................................................................3

         2.6      Resignation.....................................................................................3

         2.7      Regular Meetings................................................................................3

         2.8      Special Meetings................................................................................3

         2.9      Notice of Special Meetings......................................................................4

         2.10     Meetings by Telephone Conference Calls..........................................................4

         2.11     Quorum..........................................................................................4

         2.12     Action at Meeting...............................................................................4

         2.13     Action by Consent...............................................................................4

         2.14     Removal.........................................................................................4

         2.15     Committees......................................................................................4

         2.16     Compensation of Directors.......................................................................5

ARTICLE 3         OFFICERS........................................................................................5

         3.1      Enumeration.....................................................................................5

         3.2      Election........................................................................................5


                                      i.


<PAGE>

                                                   TABLE OF CONTENTS
                                                     (CONTINUED)

         3.3      Qualification...................................................................................5

         3.4      Tenure..........................................................................................5

         3.5      Resignation and Removal.........................................................................5

         3.6      Vacancies.......................................................................................6

         3.7      Chairman of the Board and Vice-Chairman of the Board............................................6

         3.8      Chief Executive Officer.........................................................................6

         3.9      President.......................................................................................6

         3.10     Vice Presidents.................................................................................6

         3.11     Secretary and Assistant Secretaries.............................................................7

         3.12     Treasurer and Assistant Treasurers..............................................................7

         3.13     Salaries........................................................................................7

ARTICLE 4         CAPITAL STOCK...................................................................................7

         4.1      Issuance of Stock...............................................................................7

         4.2      Certificates of Stock...........................................................................8


         4.3      Transfers.......................................................................................8

         4.4      Lost, Stolen or Destroyed Certificates..........................................................8

         4.5      Record Date.....................................................................................9

ARTICLE 5         GENERAL PROVISIONS..............................................................................9

         5.1      Fiscal Year.....................................................................................9

         5.2      Corporate Seal..................................................................................9

         5.3      Waiver of Notice................................................................................9

         5.4      Voting of Securities............................................................................9

         5.5      Evidence of Authority..........................................................................10

         5.6      Certificate of Incorporation...................................................................10

         5.7      Transactions with Interested Parties...........................................................10

         5.8      Severability...................................................................................10

         5.9      Pronouns.......................................................................................10

         5.10     Affect of Stockholders Agreement...............................................................11

ARTICLE 6         AMENDMENTS.....................................................................................11

         6.1      By the Board of Directors......................................................................11

         6.2      By the Stockholders............................................................................11
</TABLE>


                                      ii.


<PAGE>

                                     BY-LAWS

                                       OF

                           ACADIA PHARMACEUTICALS INC.


                                    ARTICLE 1

                                  STOCKHOLDERS

         1.1 PLACE OF MEETINGS. All meetings of stockholders shall be held at
such place within or without the State of Delaware as may be designated from
time to time by the Board of Directors or the President or, if not so
designated, at the registered office of the corporation.

         1.2 ANNUAL MEETING. The annual meeting of stockholders for the election
of directors and for the transaction of such other business as may properly be
brought before the meeting shall be held on a date to be fixed by the Board of
Directors or the President (which date shall not be a legal holiday in the place
where the meeting is to be held) at the time and place to be fixed by the Board
of Directors or the President and stated in the notice of the meeting. If no
annual meeting is held in accordance with the foregoing provisions, the Board of
Directors shall cause the meeting to be held as soon thereafter as convenient.
If no annual meeting is held in accordance with the foregoing provisions, a
special meeting may be held in lieu of the annual meeting, and any action taken
at that special meeting shall have the same effect as if it had been taken at
the annual meeting, and in such case all references in these By-laws to the
annual meeting of the stockholders shall be deemed to refer to such special
meeting.

         1.3 SPECIAL MEETINGS. Special meetings of stockholders may be called at
any time by the President or by the Board of Directors. Business transacted at
any special meeting of stockholders shall be limited to matters relating to the
purpose or purposes stated in the notice of meeting.

         1.4 NOTICE OF MEETINGS. Except as otherwise provided by law, written
notice of each meeting of stockholders, whether annual or special, shall be
given not less than 10 nor more than 60 days before the date of the meeting to
each stockholder entitled to vote at such meeting. The notices of all meetings
shall state the place, date and hour of the meeting. The notice of a special
meeting shall state, in addition, the purpose or purposes for which the meeting
is called. If mailed, notice is given when deposited in the United States mail,
postage prepaid, directed to the stockholder at his address as it appears on the
records of the corporation.

         1.5 VOTING LIST. The officer who has charge of the stock ledger of the
corporation shall prepare, at least 10 days before every meeting of
stockholders, a complete list of the stockholders entitled to vote at the
meeting, arranged in alphabetical order, and showing the address of each
stockholder and the number of shares registered in the name of each stockholder.
Such list shall be open to the examination of any stockholder, for any purpose
germane to the meeting, during ordinary business hours, for a period of at least
10 days prior to the meeting, at a 


                                       1.



<PAGE>

place within the city where the meeting is to be held. Upon request, a copy 
of such list will be provided by mail or facsimile to any stockholder within 
3 days of a request therefor. The list shall also be produced and kept at the 
time and place of the meeting during the whole time of the meeting, and may 
be inspected by any stockholder who is present.

         1.6 QUORUM. Except as otherwise provided by law, the Certificate of
Incorporation or these By-laws, the holders of a majority of the shares of the
capital stock of the corporation issued and outstanding and entitled to vote at
the meeting, present in person or represented by proxy, shall constitute a
quorum for the transaction of business.

         1.7 ADJOURNMENTS. Any meeting of stockholders may be adjourned to any
other time and to any other place at which a meeting of stockholders may be held
under these Bylaws by the stockholders present or represented at the meeting and
entitled to vote, although less than a quorum, or, if no stockholder is present,
by any officer entitled to preside at or to act as Secretary of such meeting. It
shall not be necessary to notify any stockholder of any adjournment of less than
30 days if the time and place of the adjourned meeting are announced at the
meeting at which adjournment is taken, unless after the adjournment a new record
date is fixed for the adjourned meeting. At the adjourned meeting, the
corporation may transact any business which might have been transacted at the
original meeting.

         1.8 VOTING AND PROXIES. Each stockholder shall have one vote for each
share of stock entitled to vote held of record by such stockholder, unless
otherwise provided in the Certificate of Incorporation. Each stockholder of
record entitled to vote at a meeting of stockholders, or to express consent or
dissent to corporate action in writing without a meeting, may vote or express
such consent or dissent in person or may authorize another person or persons to
vote or act for him by written proxy executed by the stockholder or his
authorized agent and delivered to the Secretary of the corporation. No such
proxy shall be voted or acted upon after three years from the date of its
execution, unless the proxy expressly provides for a longer period.

         1.9 ACTION AT MEETING. When a quorum is present at any meeting, the
holders of shares of stock representing a majority of the votes cast on a matter
(or if there are two or more classes of stock entitled to vote as separate
classes, then in the case of each such class, the holders of shares of stock of
that class representing a majority of the votes cast on a matter) shall decide
any matter to be voted upon by the stockholders at such meeting, except when a
different vote is required by express provision of law, the Certificate of
Incorporation or these By-Laws. When a quorum is present at any meeting, any
election by stockholders shall be determined by a plurality of the votes cast on
the election.

         1.10 ACTION WITHOUT MEETING. Any action required or permitted to be
taken at any annual or special meeting of stockholders of the corporation may be
taken without a meeting, without prior notice and without a vote, if a consent
in writing, setting forth the action so taken, is signed by the holders of
outstanding stock having not less than the minimum number of votes that would be
necessary to authorize or take such action at a meeting at which all shares
entitled to vote on such action were present and voted. Prompt notice of the
taking of corporate action without a meeting by less than unanimous written
consent shall be given to those stockholders who have not consented in writing.


                                      2.


<PAGE>


                                    ARTICLE 2

                                    DIRECTORS

         2.1 GENERAL POWERS. The business and affairs of the corporation shall
be managed by or under the direction of a Board of Directors, who may exercise
all of the powers of the corporation except as otherwise provided by law or the
Certificate of Incorporation. In the event of a vacancy in the Board of
Directors, the remaining directors, except as otherwise provided by law, may
exercise the powers of the full Board until the vacancy is filled.

         2.2 NUMBER; ELECTION AND QUALIFICATION. The number of directors which
shall constitute the whole Board of Directors shall be determined by resolution
of the stockholders or the Board of Directors, but in no event shall be less
than one. The number of directors may be decreased at any time and from time to
time either by the stockholders or by a majority of the directors then in
office, but only to eliminate vacancies existing by reason of the death,
resignation, removal or expiration of the term of one or more directors. The
directors shall be elected at the annual meeting of stockholders by such
stockholders as have the right to vote on such election. Directors need not be
stockholders of the corporation.

         2.3 ENLARGEMENT OF THE BOARD. The number of directors may be increased
at any time and from time to time by the stockholders or by a majority of the
directors then in office.

         2.4 TENURE. Each director shall hold office until the next annual
meeting and until his successor is elected and qualified, or until his earlier
death, resignation or removal.

         2.5 VACANCIES. Unless and until filled by the stockholders, any vacancy
in the Board of Directors, however occurring, including a vacancy resulting from
an enlargement of the Board, may be filled by vote of a majority of the
directors then in office, although less than a quorum, or by a sole remaining
director. A director elected to fill a vacancy shall be elected for the
unexpired term of his predecessor in office, and a director chosen to fill a
position resulting from an increase in the number of directors shall hold office
until the next annual meeting of stockholders and until his successor is elected
and qualified, or until his earlier death, resignation or removal.

         2.6 RESIGNATION. Any director may resign by delivering his written
resignation to the corporation at its principal office or to the President or
Secretary. Such resignation shall be effective upon receipt unless it is
specified to be effective at some other time or upon the happening of some other
event.

         2.7 REGULAR MEETINGS. Regular meetings of the Board of Directors may be
held without notice at such time and place, either within or without the State
of Delaware, as shall be determined from time to time by the Board of Directors;
provided that any director who is absent when such a determination is made shall
be given notice of the determination. A regular meeting of the Board of
Directors may be held without notice immediately after and at the same place as
the annual meeting of stockholders.

         2.8 SPECIAL MEETINGS. Special meetings of the Board of Directors may be
held at any time and place, within or without the State of Delaware, designated
in a call by the Chairman of 


                                     3.


<PAGE>

the Board, President, two or more directors, or by one director in the event 
that there is only a single director in office.

         2.9 NOTICE OF SPECIAL MEETINGS. Notice of any special meeting of
directors shall be given to each director by the Secretary or by the officer or
one of the directors calling the meeting. Notice shall be duly given to each
director (i) by giving notice to such director in person or by telephone at
least 48 hours in advance of the meeting, (ii) by sending a telegram, telex or
telecopy or delivering written notice by hand, to his last known business or
home address at least 48 hours in advance of the meeting, or (iii) by mailing
written notice to his last known business or home address at least 72 hours in
advance of the meeting. A notice or waiver of notice of a meeting of the Board
of Directors need not specify the purposes of the meeting.

         2.10 MEETINGS BY TELEPHONE CONFERENCE CALLS. Directors or any members
of any committee designated by the directors may participate in a meeting of the
Board of Directors or such committee by means of conference telephone or similar
communications equipment by means of which all persons participating in the
meeting can hear each other, and participation by such means shall constitute
presence in person at such meeting.

         2.11 QUORUM. A majority of the total number of the whole Board of
Directors shall constitute a quorum at all meetings of the Board of Directors.
In the event one or more of the directors shall be disqualified to vote at any
meeting, then the required quorum shall be reduced by one for each such director
so disqualified; provided, however, that in no case shall less than one-third
(1/3) of the number so fixed constitute a quorum. In the absence of a quorum at
any such meeting, a majority of the directors present may adjourn the meeting
from time to time without further notice other than announcement at the meeting,
until a quorum shall be present.

         2.12 ACTION AT MEETING. At any meeting of the Board of Directors at
which a quorum is present, the vote of a majority of those present shall be
sufficient to take any action, unless a different vote is specified by law, the
Certificate of Incorporation or these By-Laws.

         2.13 ACTION BY CONSENT. Any action, required or permitted to be taken
at any meeting of the Board of Directors or of any committee of the Board of
Directors may be taken without a meeting, if all members of the Board or
committee, as the case may be, consent to the action in writing, and the written
consents are filed with the minutes of proceedings of the Board or committee.

         2.14 REMOVAL. Except as otherwise provided by the General Corporation
Law of Delaware, any one or more or all of the directors may be removed, with or
without cause, by the holders of a majority of the shares then entitled to vote
at an election of directors, except that the directors elected by the holders of
a particular class or series of stock may be removed without cause only by vote
of the holders of a majority of the outstanding shares of such class or series.

         2.15 COMMITTEES. The Board of Directors may, by resolution passed by a
majority of the whole Board, designate one or more committees, each committee to
consist of one or more of the directors of the corporation. The Board may
designate one or more directors as alternate members of any committee, who may
replace any absent or disqualified member at any meeting of the committee. In
the absence or disqualification of a member of a committee, the member or


                                      4.


<PAGE>


members of the committee present at any meeting and not disqualified from
voting, whether or not he or they constitute a quorum, may unanimously appoint
another member of the Board of Directors to act at the meeting in the place of
any such absent or disqualified member. Any such committee, to the extent
provided in the resolution of the Board of Directors and subject to the
provisions of the General Corporation Law of the State of Delaware, shall have
and may exercise all the powers and authority of the Board of Directors in the
management of the business and affairs of the corporation and may authorize the
seal of the corporation to be affixed to all papers which may require it. Each
such committee shall keep minutes and make such reports as the Board of
Directors may from time to time request. Except as the Board of Directors may
otherwise determine, any committee may make rules for the conduct of its
business, but unless otherwise provided by the directors or in such rules, its
business shall be conducted as nearly as possible in the same manner as is
provided in these By-laws for the Board of Directors.

         2.16 COMPENSATION OF DIRECTORS. Directors may be paid such compensation
for their services and such reimbursement for expenses of attendance at meetings
as the Board of Directors may from time to time determine. No such payment shall
preclude any director from serving the corporation or any of its parent or
subsidiary corporations in any other capacity and receiving compensation for
such service.

                                    ARTICLE 3

                                    OFFICERS

         3.1 ENUMERATION. The officers of the corporation shall consist of a
Chief Executive Officer, President, a Secretary, a Treasurer and such other
officers with such other titles as the Board of Directors shall determine,
including a Chairman of the Board, a Vice Chairman of the Board, and one or more
Vice Presidents, Assistant Treasurers, and Assistant Secretaries. The Board of
Directors may appoint such other officers as it may deem appropriate.

         3.2 ELECTION. The Chief Executive Officer, President, Treasurer and
Secretary shall be elected annually by the Board of Directors at its first
meeting following the annual meeting of stockholders. Other officers may be
appointed by the Board of Directors at such meeting or at any other meeting.

         3.3 QUALIFICATION. No officer need be a stockholder. Any two or more
offices may be held by the same person.

         3.4 TENURE. Except as otherwise provided by law, by the Certificate of
Incorporation or by these By-laws, each officer shall hold office until his
successor is elected and qualified, unless a different term is specified in the
vote choosing or appointing him, or until his earlier death, resignation or
removal.

         3.5 RESIGNATION AND REMOVAL. Any officer may resign by delivering his
written resignation to the corporation at its principal office or to the
President or Secretary. Such resignation shall be effective upon receipt unless
it is specified to be effective at some other time or upon the happening of some
other event.


                                      5.


<PAGE>


         Any officer may be removed at any time, with or without cause, by vote
of a majority of the entire number of directors then in office.

         Except as the Board of Directors may otherwise determine, no officer
who resigns or is removed shall have any right to any compensation as an officer
for any period following his resignation or removal, or any right to damages on
account of such removal, whether his compensation be by the month or by the year
or otherwise, unless such compensation is expressly provided in a duly
authorized written agreement with the corporation.

         3.6 VACANCIES. The Board of Directors may fill any vacancy occurring in
any office for any reason and may, in its discretion, leave unfilled for such
period as it may determine any offices other than those of President, Treasurer
and Secretary. Each such successor shall hold office for the unexpired term of
his predecessor and until his successor is elected and qualified, or until his
earlier death, resignation or removal.

         3.7 CHAIRMAN OF THE BOARD AND VICE-CHAIRMAN OF THE BOARD. The Board of
Directors may appoint a Chairman of the Board and may designate the Chairman of
the Board as Chief Executive Officer. If the Board of Directors appoints a
Chairman of the Board, he shall perform such duties and possess such powers as
are assigned to him by the Board of Directors. If the Board of Directors
appoints a Vice Chairman of the Board, he shall, in the absence or disability of
the Chairman of the Board, perform the duties and exercise the powers of the
Chairman of the Board and shall perform such other duties and possess such other
powers as may from time to time be vested in him by the Board of Directors.

         3.8 CHIEF EXECUTIVE OFFICER. The Board of Directors may designate a
chief executive officer who shall have general supervision over the property,
business, and affairs of the Company and perform all duties incident to such
office, subject to the direction of the Board of Directors.

         3.9 PRESIDENT. The President shall have such duties and authority as
shall be assigned by the Board of Directors. In the absence of the Chairman or
the Chief Executive Officer, the President shall preside at all meetings of the
stockholders and, if he is a director, at all meetings of the Board of
Directors. Unless the Board of Directors has designated a Chief Executive
Officer, the President shall be the Chief Executive Officer of the corporation.
The President shall perform such other duties and shall have such other powers
as the Board of Directors may from time to time prescribe.

         3.10 VICE PRESIDENTS. Any Vice President shall perform such duties and
possess such powers as the Board of Directors or the President may from time to
time prescribe. In the event of the absence, inability or refusal to act of the
President, the Vice President (or if there shall be more than one, the Vice
Presidents in the order determined by the Board of Directors) shall perform the
duties of the President and when so performing shall have all the powers of and
be subject to all the restrictions upon the President. The Board of Directors
may assign to any Vice President the title of Executive Vice President, Senior
Vice President or any other title selected by the Board of Directors.


                                      6.


<PAGE>

         3.11 SECRETARY AND ASSISTANT SECRETARIES. The Secretary shall perform
such duties and shall have such powers as the Board of Directors or the
President may from time to time prescribe. In addition, the Secretary shall
perform such duties and have such powers as are incident to the office of the
secretary, including without limitation the duty and power to give notices of
all meetings of stockholders and special meetings of the Board of Directors, to
attend all meetings of stockholders and the Board of Directors and keep a record
of the proceedings, to maintain a stock ledger and prepare lists of stockholders
and their addresses as required, to be custodian of corporate records and the
corporate seal and to affix and attest to the same on documents.

         Any Assistant Secretary shall perform such duties and possess such
powers as the Board of Directors, the President or the Secretary may from time
to time prescribe. In the event of the absence, inability or refusal to act of
the Secretary, the Assistant Secretary, (or if there shall be more than one, the
Assistant Secretaries in the order determined by the Board of Directors) shall
perform the duties and exercise the powers of the Secretary.

         In the absence of the Secretary or any Assistant Secretary at any
meeting of stockholders or directors, the person presiding at the meeting shall
designate a temporary secretary to keep a record of the meeting.

         3.12 TREASURER AND ASSISTANT TREASURERS. The Treasurer shall perform
such duties and shall have such powers as may from time to time be assigned to
him by the Board of Directors or the President. In addition, the Treasurer shall
perform such duties and have such powers as are incident to the office of
treasurer, including without limitation the duty and power to keep and be
responsible for all funds and securities of the corporation, to deposit funds of
the corporation in depositories selected in accordance with these By-laws, to
disburse such funds as ordered by the Board of Directors, to make proper
accounts of such funds, and to render as required by the Board of Directors
statements of all such transactions and of the financial condition of the
corporation.

         The Assistant Treasurers shall perform such duties and possess such
powers as the Board of Directors, the President or the Treasurer may from time
to time prescribe. In the event of the absence, inability or refusal to act of
the Treasurer, the Assistant Treasurer, (or if there shall be more than one, the
Assistant Treasurers in the order determined by the Board of Directors) shall
perform the duties and exercise the powers of the Treasurer.

         3.13 SALARIES. Officers of the corporation shall be entitled to such
salaries, compensation or reimbursement as shall be fixed or allowed from time
to time by the Board of Directors.

                                    ARTICLE 4

                                  CAPITAL STOCK

         4.1 ISSUANCE OF STOCK. Unless otherwise voted by the stockholders and
subject to the provisions of the Certificate of Incorporation, the whole or any
part of any unissued balance of the authorized capital stock of the corporation
or the whole or any part of any unissued balance 


                                      7.


<PAGE>

of the authorized capital stock of the corporation held in its treasury may 
be issued, sold, transferred or otherwise disposed of by vote of the Board of 
Directors in such manner, for such consideration and on such terms as the 
Board of Directors may determine.

         4.2 CERTIFICATES OF STOCK. Every holder of stock of the corporation
shall be entitled to have a certificate, in such form as may be prescribed by
law and by the Board of Directors, certifying the number and class of shares
owned by him in the corporation. Each such certificate shall be signed by, or in
the name of the corporation by, the Chairman or Vice-Chairman, if any, of the
Board of Directors, or the President or a Vice President, and the Treasurer or
an Assistant Treasurer, or the Secretary or an Assistant Secretary of the
corporation. Any or all of the signatures on the certificate may be a facsimile.

         Each certificate for shares of stock which are subject to any
restriction on transfer pursuant to the Certificate of Incorporation, the
By-laws, applicable securities laws or any agreement among any number of
shareholders or among such holders and the corporation shall have conspicuously
noted on the face or back of the certificate either the full text of the
restriction or a statement of the existence of such restriction.

         If the corporation shall be authorized to issue more than one class of
stock or more than one series of any class, the powers, designations,
preferences and relative, participating, optional or other special rights of
each class of stock or series thereof and the qualifications, limitations or
restrictions of such preferences and/or rights shall be set forth in full or
summarized on the face or back of each certificate representing shares of such
class or series of stock, provided that in lieu of the foregoing requirements
there may be set forth on the face or back of each certificate representing
shares of such class or series of stock a statement that the corporation will
furnish without charge to each stockholder who so requests a copy of the full
text of the powers, designations, preferences and relative, participating,
optional or other special rights of each class of stock or series thereof and
the qualifications, limitations or restrictions of such preferences and/or
rights.

         4.3 TRANSFERS. Except as otherwise established by rules and regulations
adopted by the Board of Directors, and subject to applicable law, shares of
stock may be transferred on the books of the corporation by the surrender to the
corporation or its transfer agent of the certificate representing such shares
properly endorsed or accompanied by a written assignment or power of attorney
properly executed, and with such proof of authority or the authenticity of
signature as the corporation or its transfer agent may reasonably require.
Except as may be otherwise required by law, by the Certificate of Incorporation
or by these By-laws, the corporation shall be entitled to treat the record
holder of stock as shown on its books as the owner of such stock for all
purposes, including the payment of dividends and the right to vote with respect
to such stock, regardless of any transfer, pledge or other disposition of such
stock until the shares have been transferred on the books of the corporation in
accordance with the requirements of these By-laws.

         4.4 LOST, STOLEN OR DESTROYED CERTIFICATES. The corporation may issue a
new certificate of stock in place of any previously issued certificate alleged
to have been lost, stolen, or destroyed, upon such terms and conditions as the
Board of Directors may prescribe, including the presentation of reasonable
evidence of such loss, theft or destruction and the giving of such 


                                      8.


<PAGE>

indemnity as the Board of Directors may require for the protection of the 
corporation or any transfer agent or registrar.

         4.5 RECORD DATE. The Board of Directors may fix in advance a date as a
record date for the determination of the stockholders entitled to notice of or
to vote at any meeting of stockholders or to express consent (or dissent) to
corporate action in writing without a meeting, or entitled to receive payment of
any dividend or other distribution or allotment of any rights in respect of any
change, conversion or exchange of stock, or for the purpose of any other lawful
action. Such record date shall not be more than 60 nor less than 10 days before
the date of such meeting, nor more than 10 days after the date of adoption of a
record date for a written consent without a meeting, nor more than 60 days prior
to any other action to which such record date relates.

         If no record date is fixed, the record date for determining
stockholders entitled to notice of or to vote at a meeting of stockholders shall
be at the close of business on the day before the day on which notice is given,
or, if notice is waived, at the close of business on the day before the day on
which the meeting is held. The record date for determining stockholders entitled
to express consent to corporate action in writing without a meeting, when no
prior action by the Board of Directors is necessary, shall be the day on which
the first written consent is properly delivered to the corporation. The record
date for determining stockholders for any other purpose shall be at the close of
business on the day on which the Board of Directors adopts the resolution
relating to such purpose.

         A determination of stockholders of record entitled to notice of or to
vote at a meeting of stockholders shall apply to any adjournment of the meeting;
provided, however, that the Board of Directors may fix a new record date for the
adjourned meeting.

                                    ARTICLE 5

                               GENERAL PROVISIONS

         5.1 FISCAL YEAR. Except as from time to time otherwise designated by
the Board of Directors, the fiscal year of the corporation shall begin on the
first day of January in each year and end on the last day of December in each
year.

         5.2 CORPORATE SEAL. The corporate seal shall be in such form as shall
be approved by the Board of Directors.

         5.3 WAIVER OF NOTICE. Whenever any notice whatsoever is required to be
given by law, by the Certificate of Incorporation or by these By-laws, a waiver
of such notice either in writing signed by the person entitled to such notice or
such person's duly authorized attorney, or by telegraph, cable or any other
available method, whether before, at or after the time stated in such waiver, or
the appearance of such person or persons at such meeting in person or by proxy,
shall be deemed equivalent to such notice.

         5.4 VOTING OF SECURITIES. Except as the directors may otherwise
designate, the President or Treasurer may waive notice of, and act as, or
appoint any person or persons to act as, proxy or attorney-in-fact for this
corporation (with or without power of substitution) at, any 


                                      9.


<PAGE>

meeting of stockholders or shareholders of any other corporation or 
organization, the securities of which may be held by this corporation.

         5.5 EVIDENCE OF AUTHORITY. A certificate by the Secretary, or an
Assistant Secretary, or a temporary Secretary, as to any action taken by the
stockholders, directors, a committee or any officer or representative of the
corporation shall as to all persons who rely on the certificate in good faith be
conclusive evidence of such action.

         5.6 CERTIFICATE OF INCORPORATION. All references in these By-laws to
the Certificate of Incorporation shall be deemed to refer to the Certificate of
Incorporation of the corporation, as amended and in effect from time to time.

         5.7 TRANSACTIONS WITH INTERESTED PARTIES. No contract or transaction
between the corporation and one or more of the directors or officers, or between
the corporation and other corporation, partnership, association, or other
organization in which one or more of the directors or officers are directors or
officers, or have a financial interest shall be void or voidable solely for this
reason, or solely because the director or officer is present at or participates
in the meeting of the Board of Directors or a committee of the Board of
Directors which authorizes the contract or transaction or solely because his or
their votes are counted for such purpose, if:

                  (1) The material facts as to his relationship or interest and
         as to the contract or transaction are disclosed or are known to the
         Board of Directors or the committee, and the Board or committee in good
         faith authorizes the contract or transaction by the affirmative votes
         of a majority of the disinterested directors, even though the
         disinterested directors be less than a quorum;

                  (2) The material facts as to his relationship or interest and
         as to the contract or transaction are disclosed or are known to the
         stockholders entitled to vote thereon, and the contract or transaction
         is specifically approved in good faith by vote of the stockholders; or

                  (3) The contract or transaction is fair as to the corporation
         as of the time it is authorized, approved or ratified, by the Board of
         Directors, a committee of the Board of Directors, or the stockholders.

         Common or interested directors may be counted in determining the
presence of a quorum at a meeting of the Board of Directors or of a committee
which authorizes the contract or transaction.

         5.8 SEVERABILITY. Any determination that any provision of these By-laws
is for any reason inapplicable, illegal or ineffective shall not affect or
invalidate any other provision of these By-laws.

         5.9 PRONOUNS. All pronouns used in these By-laws shall be deemed to
refer to the masculine, feminine or neuter, singular or plural, as the identity
of the person or persons may require.


                                     10.


<PAGE>

         5.10 AFFECT OF STOCKHOLDERS AGREEMENT. Notwithstanding anything to the
contrary set forth herein or in the Certificate of Incorporation (as amended
from time to time), in the event of any conflict or inconsistency between the
provisions of the By Laws or the Certificate of Incorporation, on the one hand,
and the provisions of that certain Stockholders Agreement dated February __,
1997, (the "Stockholders Agreement"), by and among the Company and certain of
its stockholders, the provisions of the Stockholders Agreement shall control.

                                    ARTICLE 6

                                   AMENDMENTS

         6.1 BY THE BOARD OF DIRECTORS. These By-laws may be altered, amended or
repealed or new by-laws may be adopted by the affirmative vote of a majority of
the directors present at any regular or special meeting of the Board of
Directors at which a quorum is present.

         6.2 BY THE STOCKHOLDERS. These By-laws may be altered, amended or
repealed or new by-laws may be adopted by the affirmative vote of the holders of
a majority of the shares of the capital stock of the corporation issued and
outstanding and entitled to Vote at any regular meeting of stockholders, or at
any special meeting of stockholders, provided notice of such alteration,
amendment, repeal or adoption of new by-laws shall have been stated in the
notice of such special meeting.


                                     11.



<PAGE>



                           ACADIA PHARMACEUTICALS INC.

                              AMENDMENT TO BY-LAWS

         5.10 EFFECT OF STOCKHOLDERS AGREEMENT. Notwithstanding anything to the
contrary set forth herein or in the Certificate of Incorporation, as amended (as
may be further amended from time to time), in the event of any conflict or
inconsistency between the provisions of the By-Laws or the Certificate of
Incorporation, as amended, on the one hand, and the provisions of that certain
Amended and Restated Stockholders Agreement dated August 12, 1997, (the
"Stockholders Agreement"), by and among the Company and certain of its
stockholders, the provisions of the Stockholders Agreement shall control.


                                      1.




<PAGE>




                                     BYLAWS

                                       OF

                           ACADIA PHARMACEUTICALS INC.


        


<PAGE>

                                                   TABLE OF CONTENTS


<TABLE>
<CAPTION>
                                                                                                               PAGE
<S>                                                                                                            <C>

ARTICLE I             OFFICES.....................................................................................1

         Section 1.        Registered Office......................................................................1

         Section 2.        Other Offices..........................................................................1

ARTICLE II            CORPORATE SEAL..............................................................................1

         Section 3.        Corporate Seal.........................................................................1

ARTICLE III           STOCKHOLDERS' MEETINGS......................................................................1

         Section 4.        Place Of Meetings......................................................................1

         Section 5.        Annual Meetings........................................................................1

         Section 6.        Special Meetings.......................................................................3

         Section 7.        Notice Of Meetings.....................................................................4

         Section 8.        Quorum.................................................................................5

         Section 9.        Adjournment And Notice Of Adjourned Meetings...........................................5

         Section 10.       Voting Rights..........................................................................5

         Section 11.       Joint Owners Of Stock..................................................................6

         Section 12.       List Of Stockholders...................................................................6

         Section 13.       Action Without Meeting.................................................................6

         Section 14.       Organization...........................................................................7

ARTICLE IV            DIRECTORS...................................................................................7

         Section 15.       Number And Term Of Office..............................................................7

         Section 16.       Powers.................................................................................8

         Section 17.       Classes of Directors...................................................................8

         Section 18.       Vacancies..............................................................................8

         Section 19.       Resignation............................................................................9

         Section 20.       Meetings...............................................................................9

         Section 21.       Quorum And Voting.....................................................................10

         Section 22.       Action Without Meeting................................................................10

         Section 23.       Fees And Compensation.................................................................10

         Section 24.       Committees............................................................................10

         Section 25.       Organization..........................................................................12

ARTICLE V             OFFICERS...................................................................................12

                                                         i.


<PAGE>

                                                   TABLE OF CONTENTS
                                                      (CONTINUED)

         Section 26.       Officers Designated...................................................................12

         Section 27.       Tenure And Duties Of Officers.........................................................12

         Section 28.       Delegation Of Authority...............................................................13

         Section 29.       Resignations..........................................................................13

         Section 30.       Removal...............................................................................14

ARTICLE VI            EXECUTION OF CORPORATE INSTRUMENTS
 AND VOTING OF SECURITIES OWNED BY THE
                      CORPORATION................................................................................14

         Section 31.       Execution Of Corporate Instruments....................................................14

         Section 32.       Voting Of Securities Owned By The Corporation.........................................14

ARTICLE VII           SHARES OF STOCK............................................................................14

         Section 33.       Form And Execution Of Certificates....................................................14

         Section 34.       Lost Certificates.....................................................................15

         Section 35.       Transfers.............................................................................15

         Section 36.       Fixing Record Dates...................................................................15

         Section 37.       Registered Stockholders...............................................................16

ARTICLE VIII          OTHER SECURITIES OF THE CORPORATION........................................................17

         Section 38.       Execution Of Other Securities.........................................................17

ARTICLE IX            DIVIDENDS..................................................................................17

         Section 39.       Declaration Of Dividends..............................................................17

         Section 40.       Dividend Reserve......................................................................17

ARTICLE X             FISCAL YEAR................................................................................18

         Section 41.       Fiscal Year...........................................................................18

ARTICLE XI            INDEMNIFICATION............................................................................18

         Section 42.       Indemnification Of Directors, Executive Officers, Other Officers, Employees
                           And Other Agents......................................................................18

ARTICLE XII           NOTICES....................................................................................21

         Section 43.       Notices...............................................................................21

ARTICLE XIII          AMENDMENTS.................................................................................22

         Section 44.       Amendments............................................................................22

ARTICLE XIV           LOANS TO OFFICERS..........................................................................23


                                                         ii.


<PAGE>

                                                   TABLE OF CONTENTS
                                                     (CONTINUED)

         Section 45.       Loans To Officers.....................................................................23

ARTICLE XV            TRANSFERS OF COMMON STOCK..................................................................23

         Section 46.       Prohibition of Transfers..............................................................23

         Section 47.       Exempt Transfers......................................................................23

         Section 48.       Notice................................................................................23

         Section 49.       Right of First Refusal................................................................23

         Section 50.       Expiration............................................................................24

</TABLE>


                                                         iii.


<PAGE>



                                     BYLAWS

                                       OF

                           ACADIA PHARMACEUTICALS INC.



                                    ARTICLE I

                                     OFFICES

         SECTION 1. REGISTERED OFFICE. The registered office of the corporation
in the State of Delaware shall be in the City of Wilmington, County of New
Castle.

         SECTION 2. OTHER OFFICES. The corporation shall also have and maintain
an office or principal place of business at such place as may be fixed by the
Board of Directors, and may also have offices at such other places, both within
and without the State of Delaware as the Board of Directors may from time to
time determine or the business of the corporation may require.

                                   ARTICLE II

                                 CORPORATE SEAL

         SECTION 3. CORPORATE SEAL. The corporate seal shall consist of a die
bearing the name of the corporation and the inscription, "Corporate
Seal-Delaware." Said seal may be used by causing it or a facsimile thereof to be
impressed or affixed or reproduced or otherwise.

                                   ARTICLE III

                             STOCKHOLDERS' MEETINGS

         SECTION 4. PLACE OF MEETINGS. Meetings of the stockholders of the
corporation shall be held at such place, either within or without the State of
Delaware, as may be designated from time to time by the Board of Directors, or,
if not so designated, then at the office of the corporation required to be
maintained pursuant to Section 2 hereof.

         SECTION 5. ANNUAL MEETINGS.

                  (a) The annual meeting of the stockholders of the corporation,
for the purpose of election of directors and for such other business as may
lawfully come before it, shall be held on such date and at such time as may be
designated from time to time by the Board of Directors. Nominations of persons
for election to the Board of Directors of the corporation and the proposal of
business to be considered by the stockholders may be made at an annual meeting
of stockholders: (i) pursuant to the corporation's notice of meeting of
stockholders; (ii) by or at the direction of the Board of Directors; or (iii) by
any stockholder of the corporation who was a 


                                     1.


<PAGE>

stockholder of record at the time of giving of notice provided for in the 
following paragraph, who is entitled to vote at the meeting and who complied 
with the notice procedures set forth in Section 5.

                  (b) At an annual meeting of the stockholders, only such
business shall be conducted as shall have been properly brought before the
meeting. For nominations or other business to be properly brought before an
annual meeting by a stockholder pursuant to clause (iii) of Section 5(a) of
these Bylaws, (i) the stockholder must have given timely notice thereof in
writing to the Secretary of the corporation, (ii) such other business must be a
proper matter for stockholder action under the Delaware General Corporation Law
("DGCL"), (iii) if the stockholder, or the beneficial owner on whose behalf any
such proposal or nomination is made, has provided the corporation with a
Solicitation Notice (as defined in this Section 5(b)), such stockholder or
beneficial owner must, in the case of a proposal, have delivered a proxy
statement and form of proxy to holders of at least the percentage of the
corporation's voting shares required under applicable law to carry any such
proposal, or, in the case of a nomination or nominations, have delivered a proxy
statement and form of proxy to holders of a percentage of the corporation's
voting shares reasonably believed by such stockholder or beneficial owner to be
sufficient to elect the nominee or nominees proposed to be nominated by such
stockholder, and must, in either case, have included in such materials the
Solicitation Notice, and (iv) if no Solicitation Notice relating thereto has
been timely provided pursuant to this section, the stockholder or beneficial
owner proposing such business or nomination must not have solicited a number of
proxies sufficient to have required the delivery of such a Solicitation Notice
under this Section 5. To be timely, a stockholder's notice shall be delivered to
the Secretary at the principal executive offices of the Corporation not later
than the close of business on the ninetieth (90th) day nor earlier than the
close of business on the one hundred twentieth (120th) day prior to the first
anniversary of the preceding year's annual meeting; provided, however, that in
the event that the date of the annual meeting is advanced more than thirty (30)
days prior to or delayed by more than thirty (30) days after the anniversary of
the preceding year's annual meeting, notice by the stockholder to be timely must
be so delivered not earlier than the close of business on the one hundred
twentieth (120th) day prior to such annual meeting and not later than the close
of business on the later of the ninetieth (90th) day prior to such annual
meeting or the tenth (10th) day following the day on which public announcement
of the date of such meeting is first made. In no event shall the public
announcement of an adjournment of an annual meeting commence a new time period
for the giving of a stockholder's notice as described above. Such stockholder's
notice shall set forth: (A) as to each person whom the stockholder proposed to
nominate for election or reelection as a director all information relating to
such person that is required to be disclosed in solicitations of proxies for
election of directors in an election contest, or is otherwise required, in each
case pursuant to Regulation 14A under the Securities Exchange Act of 1934, as
amended (the "1934 Act") and Rule 14a-11 thereunder (including such person's
written consent to being named in the proxy statement as a nominee and to
serving as a director if elected); (B) as to any other business that the
stockholder proposes to bring before the meeting, a brief description of the
business desired to be brought before the meeting, the reasons for conducting
such business at the meeting and any material interest in such business of such
stockholder and the beneficial owner, if any, on whose behalf the proposal is
made; and (C) as to the stockholder giving the notice and the beneficial owner,
if any, on whose behalf the nomination or proposal is made (i) the name and
address of such stockholder, as they appear on the corporation's books, 


                                     2.


<PAGE>

and of such beneficial owner, (ii) the class and number of shares of the 
corporation which are owned beneficially and of record by such stockholder 
and such beneficial owner, and (iii) whether either such stockholder or 
beneficial owner intends to deliver a proxy statement and form of proxy to 
holders of, in the case of the proposal, at least the percentage of the 
corporation's voting shares required under applicable law to carry the 
proposal or, in the case of a nomination or nominations, a sufficient number 
of holders of the corporation's voting shares to elect such nominee or 
nominees (an affirmative statement of such intent, a "Solicitation Notice").

                  (c) Notwithstanding anything in the second sentence of Section
5(b) of these Bylaws to the contrary, in the event that the number of directors
to be elected to the Board of Directors of the Corporation is increased and
there is no public announcement naming all of the nominees for director or
specifying the size of the increased Board of Directors made by the corporation
at least one hundred (100) days prior to the first anniversary of the preceding
year's annual meeting, a stockholder's notice required by this Section 5 shall
also be considered timely, but only with respect to nominees for any new
positions created by such increase, if it shall be delivered to the Secretary at
the principal executive offices of the corporation not later than the close of
business on the tenth (10th) day following the day on which such public
announcement is first made by the corporation.

                  (d) Only such persons who are nominated in accordance with the
procedures set forth in this Section 5 shall be eligible to serve as directors
and only such business shall be conducted at a meeting of stockholders as shall
have been brought before the meeting in accordance with the procedures set forth
in this Section 5. Except as otherwise provided by law, the Chairman of the
meeting shall have the power and duty to determine whether a nomination or any
business proposed to be brought before the meeting was made, or proposed, as the
case may be, in accordance with the procedures set forth in these Bylaws and, if
any proposed nomination or business is not in compliance with these Bylaws, to
declare that such defective proposal or nomination shall not be presented for
stockholder action at the meeting and shall be disregarded.

                  (e) Notwithstanding the foregoing provisions of this Section
5, in order to include information with respect to a stockholder proposal in the
proxy statement and form of proxy for a stockholders' meeting, stockholders must
provide notice as required by the regulations promulgated under the 1934 Act.
Nothing in these Bylaws shall be deemed to affect any rights of stockholders to
request inclusion of proposals in the corporation proxy statement pursuant to
Rule 14a-8 under the 1934 Act.

                  (f) For purposes of this Section 5, "public announcement"
shall mean disclosure in a press release reported by the Dow Jones News Service,
Associated Press or comparable national news service or in a document publicly
filed by the corporation with the Securities and Exchange Commission pursuant to
Section 13, 14 or 15(d) of the 1934 Act.

         SECTION 6. SPECIAL MEETINGS.

                  (a) Special meetings of the stockholders of the corporation
may be called, for any purpose or purposes, by (i) the Chairman of the Board of
Directors, (ii) the Chief Executive Officer, or (iii) the Board of Directors
pursuant to a resolution adopted by a majority of the total 


                                     3.


<PAGE>

number of authorized directors (whether or not there exist any vacancies in 
previously authorized directorships at the time any such resolution is 
presented to the Board of Directors for adoption).

                  (b) If a special meeting is properly called by any person or
persons other than the Board of Directors, the request shall be in writing,
specifying the general nature of the business proposed to be transacted, and
shall be delivered personally or sent by registered mail or by telegraphic or
other facsimile transmission to the Chairman of the Board of Directors, the
Chief Executive Officer, or the Secretary of the corporation. No business may be
transacted at such special meeting otherwise than specified in such notice. The
Board of Directors shall determine the time and place of such special meeting,
which shall be held not less than thirty-five (35) nor more than one hundred
twenty (120) days after the date of the receipt of the request. Upon
determination of the time and place of the meeting, the officer receiving the
request shall cause notice to be given to the stockholders entitled to vote, in
accordance with the provisions of Section 7 of these Bylaws. If the notice is
not given within one hundred (100) days after the receipt of the request, the
person or persons properly requesting the meeting may set the time and place of
the meeting and give the notice. Nothing contained in this paragraph (b) shall
be construed as limiting, fixing, or affecting the time when a meeting of
stockholders called by action of the Board of Directors may be held.

                  (c) Nominations of persons for election to the Board of
Directors may be made at a special meeting of stockholders at which directors
are to be elected pursuant to the corporation's notice of meeting (i) by or at
the direction of the Board of Directors or (ii) by any stockholder of the
corporation who is a stockholder of record at the time of giving notice provided
for in these Bylaws who shall be entitled to vote at the meeting and who
complies with the notice procedures set forth in this Section 6(c). In the event
the corporation calls a special meeting of stockholders for the purpose of
electing one or more directors to the Board of Directors, any such stockholder
may nominate a person or persons (as the case may be), for election to such
position(s) as specified in the corporation's notice of meeting, if the
stockholder's notice required by Section 5(b) of these Bylaws shall be delivered
to the Secretary at the principal executive offices of the corporation not
earlier than the close of business on the one hundred twentieth (120th) day
prior to such special meeting and not later than the close of business on the
later of the ninetieth (90th) day prior to such meeting or the tenth (10th) day
following the day on which public announcement is first made of the date of the
special meeting and of the nominees proposed by the Board of Directors to be
elected at such meeting. In no event shall the public announcement of an
adjournment of a special meeting commence a new time period for the giving of a
stockholder's notice as described above.

         SECTION 7. NOTICE OF MEETINGS. Except as otherwise provided by law or
the Certificate of Incorporation, written notice of each meeting of stockholders
shall be given not less than ten (10) nor more than sixty (60) days before the
date of the meeting to each stockholder entitled to vote at such meeting, such
notice to specify the place, date and hour and purpose or purposes of the
meeting. Notice of the time, place and purpose of any meeting of stockholders
may be waived in writing, signed by the person entitled to notice thereof,
either before or after such meeting, and will be waived by any stockholder by
his attendance thereat in person or by proxy, except when the stockholder
attends a meeting for the express purpose of objecting, at the beginning of the
meeting, to the transaction of any business because the meeting 


                                      4.


<PAGE>

is not lawfully called or convened. Any stockholder so waiving notice of such 
meeting shall be bound by the proceedings of any such meeting in all respects 
as if due notice thereof had been given.

         SECTION 8. QUORUM. At all meetings of stockholders, except where
otherwise provided by statute or by the Certificate of Incorporation, or by
these Bylaws, the presence, in person or by proxy duly authorized, of the
holders of a majority of the outstanding shares of stock entitled to vote shall
constitute a quorum for the transaction of business. In the absence of a quorum,
any meeting of stockholders may be adjourned, from time to time, either by the
chairman of the meeting or by vote of the holders of a majority of the shares
represented thereat, but no other business shall be transacted at such meeting.
The stockholders present at a duly called or convened meeting, at which a quorum
is present, may continue to transact business until adjournment, notwithstanding
the withdrawal of enough stockholders to leave less than a quorum. Except as
otherwise provided by statute, the Certificate of Incorporation or these Bylaws,
in all matters other than the election of directors, the affirmative vote of the
majority of shares present in person or represented by proxy at the meeting and
entitled to vote on the subject matter shall be the act of the stockholders.
Except as otherwise provided by statute, the Certificate of Incorporation or
these Bylaws, directors shall be elected by a plurality of the votes of the
shares present in person or represented by proxy at the meeting and entitled to
vote on the election of directors. Where a separate vote by a class or classes
or series is required, except where otherwise provided by the statute or by the
Certificate of Incorporation or these Bylaws, a majority of the outstanding
shares of such class or classes or series, present in person or represented by
proxy, shall constitute a quorum entitled to take action with respect to that
vote on that matter and, except where otherwise provided by the statute or by
the Certificate of Incorporation or these Bylaws, the affirmative vote of the
majority (plurality, in the case of the election of directors) of the votes cast
by the holders of shares of such class or classes or series shall be the act of
such class or classes or series.

         SECTION 9. ADJOURNMENT AND NOTICE OF ADJOURNED MEETINGS. Any meeting of
stockholders, whether annual or special, may be adjourned from time to time
either by the chairman of the meeting or by the vote of a majority of the shares
casting votes. When a meeting is adjourned to another time or place, notice need
not be given of the adjourned meeting if the time and place thereof are
announced at the meeting at which the adjournment is taken. At the adjourned
meeting, the corporation may transact any business which might have been
transacted at the original meeting. If the adjournment is for more than thirty
(30) days or if after the adjournment a new record date is fixed for the
adjourned meeting, a notice of the adjourned meeting shall be given to each
stockholder of record entitled to vote at the meeting.

         SECTION 10. VOTING RIGHTS. For the purpose of determining those
stockholders entitled to vote at any meeting of the stockholders, except as
otherwise provided by law, only persons in whose names shares stand on the stock
records of the corporation on the record date, as provided in Section 12 of
these Bylaws, shall be entitled to vote at any meeting of stockholders. Every
person entitled to vote shall have the right to do so either in person or by an
agent or agents authorized by a proxy granted in accordance with Delaware law.
An agent so appointed need not be a stockholder. No proxy shall be voted after
three (3) years from its date of creation unless the proxy provides for a longer
period.


                                     5.


<PAGE>

         SECTION 11. JOINT OWNERS OF STOCK. If shares or other securities having
voting power stand of record in the names of two (2) or more persons, whether
fiduciaries, members of a partnership, joint tenants, tenants in common, tenants
by the entirety, or otherwise, or if two (2) or more persons have the same
fiduciary relationship respecting the same shares, unless the Secretary is given
written notice to the contrary and is furnished with a copy of the instrument or
order appointing them or creating the relationship wherein it is so provided,
their acts with respect to voting shall have the following effect: (a) if only
one (1) votes, his act binds all; (b) if more than one (1) votes, the act of the
majority so voting binds all; (c) if more than one (1) votes, but the vote is
evenly split on any particular matter, each faction may vote the securities in
question proportionally, or may apply to the Delaware Court of Chancery for
relief as provided in the DGCL, Section 217(b). If the instrument filed with the
Secretary shows that any such tenancy is held in unequal interests, a majority
or even-split for the purpose of subsection (c) shall be a majority or
even-split in interest.

         SECTION 12. LIST OF STOCKHOLDERS. The Secretary shall prepare and make,
at least ten (10) days before every meeting of stockholders, a complete list of
the stockholders entitled to vote at said meeting, arranged in alphabetical
order, showing the address of each stockholder and the number of shares
registered in the name of each stockholder. Such list shall be open to the
examination of any stockholder, for any purpose germane to the meeting, during
ordinary business hours, for a period of at least ten (10) days prior to the
meeting, either at a place within the city where the meeting is to be held,
which place shall be specified in the notice of the meeting, or, if not
specified, at the place where the meeting is to be held. The list shall be
produced and kept at the time and place of meeting during the whole time thereof
and may be inspected by any stockholder who is present.

         SECTION 13. ACTION WITHOUT MEETING.

                  (a) Unless otherwise provided in the Certificate of
Incorporation, any action required by statute to be taken at any annual or
special meeting of the stockholders, or any action which may be taken at any
annual or special meeting of the stockholders, may be taken without a meeting,
without prior notice and without a vote, if a consent in writing, setting forth
the action so taken, shall be signed by the holders of outstanding stock having
not less than the minimum number of votes that would be necessary to authorize
or take such action at a meeting at which all shares entitled to vote thereon
were present and voted.

                  (b) Every written consent shall bear the date of signature of
each stockholder who signs the consent, and no written consent shall be
effective to take the corporate action referred to therein unless, within sixty
(60) days of the earliest dated consent delivered to the corporation in the
manner herein required, written consents signed by a sufficient number of
stockholders to take action are delivered to the corporation by delivery to its
registered office in the State of Delaware, its principal place of business or
an officer or agent of the corporation having custody of the book in which
proceedings of meetings of stockholders are recorded. Delivery made to a
corporation's registered office shall be by hand or by certified or registered
mail, return receipt requested.

                  (c) Prompt notice of the taking of the corporate action
without a meeting by less than unanimous written consent shall be given to those
stockholders who have not consented 


                                      6.


<PAGE>

in writing and who, if the action had been taken at a meeting, would have 
been entitled to notice of the meeting if the record date for such meeting 
had been the date that written consents signed by a sufficient number of 
stockholders to take action were delivered to the corporation as provided in 
Section 228 (c) of the DGCL. If the action which is consented to is such as 
would have required the filing of a certificate under any section of the DGCL 
if such action had been voted on by stockholders at a meeting thereof, then 
the certificate filed under such section shall state, in lieu of any 
statement required by such section concerning any vote of stockholders, that 
written consent has been given in accordance with Section 228 of the DGCL.

                  (d) Notwithstanding the foregoing, no such action by written
consent may be taken following the closing of the initial public offering
pursuant to an effective registration statement under the Securities Act of
1933, as amended (the "1933 Act"), covering the offer and sale of Common Stock
of the corporation (the "Initial Public Offering").

         SECTION 14. ORGANIZATION.

                  (a) At every meeting of stockholders, the Chairman of the
Board of Directors, or, if a Chairman has not been appointed or is absent, the
President, or, if the President is absent, a chairman of the meeting chosen by a
majority in interest of the stockholders entitled to vote, present in person or
by proxy, shall act as chairman. The Secretary, or, in his absence, an Assistant
Secretary directed to do so by the President, shall act as secretary of the
meeting.

                  (b) The Board of Directors of the corporation shall be
entitled to make such rules or regulations for the conduct of meetings of
stockholders as it shall deem necessary, appropriate or convenient. Subject to
such rules and regulations of the Board of Directors, if any, the chairman of
the meeting shall have the right and authority to prescribe such rules,
regulations and procedures and to do all such acts as, in the judgment of such
chairman, are necessary, appropriate or convenient for the proper conduct of the
meeting, including, without limitation, establishing an agenda or order of
business for the meeting, rules and procedures for maintaining order at the
meeting and the safety of those present, limitations on participation in such
meeting to stockholders of record of the corporation and their duly authorized
and constituted proxies and such other persons as the chairman shall permit,
restrictions on entry to the meeting after the time fixed for the commencement
thereof, limitations on the time allotted to questions or comments by
participants and regulation of the opening and closing of the polls for
balloting on matters which are to be voted on by ballot. Unless and to the
extent determined by the Board of Directors or the chairman of the meeting,
meetings of stockholders shall not be required to be held in accordance with
rules of parliamentary procedure.

                                   ARTICLE IV

                                    DIRECTORS

         SECTION 15. NUMBER AND TERM OF OFFICE. The authorized number of
directors of the corporation shall be fixed in accordance with the Certificate
of Incorporation. Directors need not be stockholders unless so required by the
Certificate of Incorporation. If for any reason, the directors shall not have
been elected at an annual meeting, they may be elected as soon thereafter 


                                     7.


<PAGE>

as convenient at a special meeting of the stockholders called for that 
purpose in the manner provided in these Bylaws.

         SECTION 16. POWERS. The powers of the corporation shall be exercised,
its business conducted and its property controlled by the Board of Directors,
except as may be otherwise provided by statute or by the Certificate of
Incorporation.

         SECTION 17. CLASSES OF DIRECTORS. Subject to the rights of the holders
of any series of Preferred Stock to elect additional directors under specified
circumstances, following the closing of the Initial Public Offering, the
directors shall be divided into three classes designated as Class I, Class II
and Class III, respectively. Directors shall be assigned to each class in
accordance with a resolution or resolutions adopted by the Board of Directors.
At the first annual meeting of stockholders following the closing of the Initial
Public Offering, the term of office of the Class I directors shall expire and
Class I directors shall be elected for a full term of three years. At the second
annual meeting of stockholders following the closing of the Initial Public
Offering, the term of office of the Class II directors shall expire and Class II
directors shall be elected for a full term of three years. At the third annual
meeting of stockholders following the closing of the Initial Public Offering,
the term of office of the Class III directors shall expire and Class III
directors shall be elected for a full term of three years. At each succeeding
annual meeting of stockholders, directors shall be elected for a full term of
three years to succeed the directors of the class whose terms expire at such
annual meeting.

         Notwithstanding the foregoing provisions of this section, each director
shall serve until his successor is duly elected and qualified or until his
death, resignation or removal. No decrease in the number of directors
constituting the Board of Directors shall shorten the term of any incumbent
director.

         SECTION 18. VACANCIES.

                  (a) Unless otherwise provided in the Certificate of
Incorporation, any vacancies on the Board of Directors resulting from death,
resignation, disqualification, removal or other causes and any newly created
directorships resulting from any increase in the number of directors shall,
unless the Board of Directors determines by resolution that any such vacancies
or newly created directorships shall be filled by stockholders, be filled only
by the affirmative vote of a majority of the directors then in office, even
though less than a quorum of the Board of Directors. Any director elected in
accordance with the preceding sentence shall hold office for the remainder of
the full term of the director for which the vacancy was created or occurred and
until such director's successor shall have been elected and qualified. A vacancy
in the Board of Directors shall be deemed to exist under this Section 18 in the
case of the death, removal or resignation of any director.

                  (b) If at the time of filling any vacancy or any newly created
directorship, the directors then in office shall constitute less than a majority
of the whole board (as constituted immediately prior to any such increase), the
Delaware Court of Chancery may, upon application of any stockholder or
stockholders holding at least ten percent (10%) of the total number of the
shares at the time outstanding having the right to vote for such directors,
summarily order an election to be held to fill any such vacancies or newly
created directorships, or to replace the 


                                      8.


<PAGE>

directors chosen by the directors then in offices as aforesaid, which 
election shall be governed by Section 211 of the DGCL.

         SECTION 19. RESIGNATION. Any director may resign at any time by
delivering his written resignation to the Secretary, such resignation to specify
whether it will be effective at a particular time, upon receipt by the Secretary
or at the pleasure of the Board of Directors. If no such specification is made,
it shall be deemed effective at the pleasure of the Board of Directors. When one
or more directors shall resign from the Board of Directors, effective at a
future date, a majority of the directors then in office, including those who
have so resigned, shall have power to fill such vacancy or vacancies, the vote
thereon to take effect when such resignation or resignations shall become
effective, and each Director so chosen shall hold office for the unexpired
portion of the term of the Director whose place shall be vacated and until his
successor shall have been duly elected and qualified.

         SECTION 20. MEETINGS.

                  (a) ANNUAL MEETINGS. The annual meeting of the Board of
Directors shall be held immediately before or after the annual meeting of
stockholders and at the place where such meeting is held. No notice of an annual
meeting of the Board of Directors shall be necessary and such meeting shall be
held for the purpose of electing officers and transacting such other business as
may lawfully come before it.

                  (b) REGULAR MEETINGS. Unless otherwise restricted by the
Certificate of Incorporation, regular meetings of the Board of Directors may be
held at any time or date and at any place within or without the State of
Delaware which has been designated by the Board of Directors and publicized
among all directors. No formal notice shall be required for regular meetings of
the Board of Directors.

                  (c) SPECIAL MEETINGS. Unless otherwise restricted by the
Certificate of Incorporation, special meetings of the Board of Directors may be
held at any time and place within or without the State of Delaware whenever
called by the Chairman of the Board, the President or any two of the directors.

                  (d) TELEPHONE MEETINGS. Any member of the Board of Directors,
or of any committee thereof, may participate in a meeting by means of conference
telephone or similar communications equipment by means of which all persons
participating in the meeting can hear each other, and participation in a meeting
by such means shall constitute presence in person at such meeting.

                  (e) NOTICE OF MEETINGS. Notice of the time and place of all
meetings of the Board of Directors shall be orally or in writing, by telephone,
including a voice messaging system or other system or technology designed to
record and communicate messages, facsimile, telegraph or telex, or by electronic
mail or other electronic means, during normal business hours, at least
twenty-four (24) hours before the date and time of the meeting, or sent in
writing to each director by first class mail, charges prepaid, at least three
(3) days before the date of the meeting. Notice of any meeting may be waived in
writing at any time before or after the meeting and will be waived by any
director by attendance thereat, except when the director attends the meeting for


                                      9.


<PAGE>

the express purpose of objecting, at the beginning of the meeting, to the
transaction of any business because the meeting is not lawfully called or
convened.

                  (f) WAIVER OF NOTICE. The transaction of all business at any
meeting of the Board of Directors, or any committee thereof, however called or
noticed, or wherever held, shall be as valid as though had at a meeting duly
held after regular call and notice, if a quorum be present and if, either before
or after the meeting, each of the directors not present shall sign a written
waiver of notice. All such waivers shall be filed with the corporate records or
made a part of the minutes of the meeting.

         SECTION 21. QUORUM AND VOTING.

                  (a) Unless the Certificate of Incorporation requires a greater
number and except with respect to indemnification questions arising under
Section 43 hereof, for which a quorum shall be one-third of the exact number of
directors fixed from time to time in accordance with the Certificate of
Incorporation, a quorum of the Board of Directors shall consist of a majority of
the exact number of directors fixed from time to time by the Board of Directors
in accordance with the Certificate of Incorporation; PROVIDED, HOWEVER, at any
meeting whether a quorum be present or otherwise, a majority of the directors
present may adjourn from time to time until the time fixed for the next regular
meeting of the Board of Directors, without notice other than by announcement at
the meeting.

                  (b) At each meeting of the Board of Directors at which a
quorum is present, all questions and business shall be determined by the
affirmative vote of a majority of the directors present, unless a different vote
be required by law, the Certificate of Incorporation or these Bylaws.

         SECTION 22. ACTION WITHOUT MEETING. Unless otherwise restricted by the
Certificate of Incorporation or these Bylaws, any action required or permitted
to be taken at any meeting of the Board of Directors or of any committee thereof
may be taken without a meeting, if all members of the Board of Directors or
committee, as the case may be, consent thereto in writing, and such writing or
writings are filed with the minutes of proceedings of the Board of Directors or
committee.

         SECTION 23. FEES AND COMPENSATION. Directors shall be entitled to such
compensation for their services as may be approved by the Board of Directors,
including, if so approved, by resolution of the Board of Directors, a fixed sum
and expenses of attendance, if any, for attendance at each regular or special
meeting of the Board of Directors and at any meeting of a committee of the Board
of Directors. Nothing herein contained shall be construed to preclude any
director from serving the corporation in any other capacity as an officer,
agent, employee, or otherwise and receiving compensation therefor.

         SECTION 24. COMMITTEES.

                  (a) EXECUTIVE COMMITTEE. The Board of Directors may appoint an
Executive Committee to consist of one (1) or more members of the Board of
Directors. The Executive Committee, to the extent permitted by law and provided
in the resolution of the Board of 


                                     10.


<PAGE>

Directors shall have and may exercise all the powers and authority of the 
Board of Directors in the management of the business and affairs of the 
corporation, and may authorize the seal of the corporation to be affixed to 
all papers which may require it; but no such committee shall have the power 
or authority in reference to (i) approving or adopting, or recommending to 
the stockholders, any action or matter expressly required by the DGCL to be 
submitted to stockholders for approval, or (ii) adopting, amending or 
repealing any bylaw of the corporation.

                  (b) OTHER COMMITTEES. The Board of Directors may, from time to
time, appoint such other committees as may be permitted by law. Such other
committees appointed by the Board of Directors shall consist of one (1) or more
members of the Board of Directors and shall have such powers and perform such
duties as may be prescribed by the resolution or resolutions creating such
committees, but in no event shall any such committee have the powers denied to
the Executive Committee in these Bylaws.

                  (c) TERM. Each member of a committee of the Board of Directors
shall serve a term on the committee coexistent with such member's term on the
Board of Directors. The Board of Directors, subject to any requirements of any
outstanding series of preferred Stock and the provisions of subsections (a) or
(b) of this Bylaw, may at any time increase or decrease the number of members of
a committee or terminate the existence of a committee. The membership of a
committee member shall terminate on the date of his death or voluntary
resignation from the committee or from the Board of Directors. The Board of
Directors may at any time for any reason remove any individual committee member
and the Board of Directors may fill any committee vacancy created by death,
resignation, removal or increase in the number of members of the committee. The
Board of Directors may designate one or more directors as alternate members of
any committee, who may replace any absent or disqualified member at any meeting
of the committee, and, in addition, in the absence or disqualification of any
member of a committee, the member or members thereof present at any meeting and
not disqualified from voting, whether or not he or they constitute a quorum, may
unanimously appoint another member of the Board of Directors to act at the
meeting in the place of any such absent or disqualified member.

                  (d) MEETINGS. Unless the Board of Directors shall otherwise
provide, regular meetings of the Executive Committee or any other committee
appointed pursuant to this Section 25 shall be held at such times and places as
are determined by the Board of Directors, or by any such committee, and when
notice thereof has been given to each member of such committee, no further
notice of such regular meetings need be given thereafter. Special meetings of
any such committee may be held at any place which has been determined from time
to time by such committee, and may be called by any director who is a member of
such committee, upon written notice to the members of such committee of the time
and place of such special meeting given in the manner provided for the giving of
written notice to members of the Board of Directors of the time and place of
special meetings of the Board of Directors. Notice of any special meeting of any
committee may be waived in writing at any time before or after the meeting and
will be waived by any director by attendance thereat, except when the director
attends such special meeting for the express purpose of objecting, at the
beginning of the meeting, to the transaction of any business because the meeting
is not lawfully called or convened. A majority of the authorized number of
members of any such committee shall 


                                     11.


<PAGE>

constitute a quorum for the transaction of business, and the act of a 
majority of those present at any meeting at which a quorum is present shall 
be the act of such committee.

         SECTION 25. ORGANIZATION. At every meeting of the directors, the
Chairman of the Board of Directors, or, if a Chairman has not been appointed or
is absent, the President (if a director), or if the President is absent, the
most senior Vice President (if a director), or, in the absence of any such
person, a chairman of the meeting chosen by a majority of the directors present,
shall preside over the meeting. The Secretary, or in his absence, any Assistant
Secretary directed to do so by the President, shall act as secretary of the
meeting.

                                    ARTICLE V

                                    OFFICERS

         SECTION 26. OFFICERS DESIGNATED. The officers of the corporation shall
include, if and when designated by the Board of Directors, the Chairman of the
Board of Directors, the Chief Executive Officer, the President, one or more Vice
Presidents, the Secretary, the Chief Financial Officer, the Treasurer and the
Controller, all of whom shall be elected at the annual organizational meeting of
the Board of Directors. The Board of Directors may also appoint one or more
Assistant Secretaries, Assistant Treasurers, Assistant Controllers and such
other officers and agents with such powers and duties as it shall deem
necessary. The Board of Directors may assign such additional titles to one or
more of the officers as it shall deem appropriate. Any one person may hold any
number of offices of the corporation at any one time unless specifically
prohibited therefrom by law. The salaries and other compensation of the officers
of the corporation shall be fixed by or in the manner designated by the Board of
Directors.

         SECTION 27. TENURE AND DUTIES OF OFFICERS.

                  (a) GENERAL. All officers shall hold office at the pleasure of
the Board of Directors and until their successors shall have been duly elected
and qualified, unless sooner removed. Any officer elected or appointed by the
Board of Directors may be removed at any time by the Board of Directors. If the
office of any officer becomes vacant for any reason, the vacancy may be filled
by the Board of Directors.

                  (b) DUTIES OF CHAIRMAN OF THE BOARD OF DIRECTORS. The Chairman
of the Board of Directors, when present, shall preside at all meetings of the
stockholders and the Board of Directors. The Chairman of the Board of Directors
shall perform other duties commonly incident to his office and shall also
perform such other duties and have such other powers, as the Board of Directors
shall designate from time to time. If there is no President, then the Chairman
of the Board of Directors shall also serve as the Chief Executive Officer of the
corporation and shall have the powers and duties prescribed in paragraph (c) of
this Section 28.

                  (c) DUTIES OF PRESIDENT. The President shall preside at all
meetings of the stockholders and at all meetings of the Board of Directors,
unless the Chairman of the Board of Directors has been appointed and is present.
Unless some other officer has been elected Chief Executive Officer of the
corporation, the President shall be the chief executive officer of the
corporation and shall, subject to the control of the Board of Directors, have
general supervision, 


                                     12.


<PAGE>

direction and control of the business and officers of the corporation. The 
President shall perform other duties commonly incident to his office and 
shall also perform such other duties and have such other powers, as the Board 
of Directors shall designate from time to time.

                  (d) DUTIES OF VICE PRESIDENTS. The Vice Presidents may assume
and perform the duties of the President in the absence or disability of the
President or whenever the office of President is vacant. The Vice Presidents
shall perform other duties commonly incident to their office and shall also
perform such other duties and have such other powers as the Board of Directors
or the President shall designate from time to time.

                  (e) DUTIES OF SECRETARY. The Secretary shall attend all
meetings of the stockholders and of the Board of Directors and shall record all
acts and proceedings thereof in the minute book of the corporation. The
Secretary shall give notice in conformity with these Bylaws of all meetings of
the stockholders and of all meetings of the Board of Directors and any committee
thereof requiring notice. The Secretary shall perform all other duties given him
in these Bylaws and other duties commonly incident to his office and shall also
perform such other duties and have such other powers, as the Board of Directors
shall designate from time to time. The President may direct any Assistant
Secretary to assume and perform the duties of the Secretary in the absence or
disability of the Secretary, and each Assistant Secretary shall perform other
duties commonly incident to his office and shall also perform such other duties
and have such other powers as the Board of Directors or the President shall
designate from time to time.

                  (f) DUTIES OF CHIEF FINANCIAL OFFICER. The Chief Financial
Officer shall keep or cause to be kept the books of account of the corporation
in a thorough and proper manner and shall render statements of the financial
affairs of the corporation in such form and as often as required by the Board of
Directors or the President. The Chief Financial Officer, subject to the order of
the Board of Directors, shall have the custody of all funds and securities of
the corporation. The Chief Financial Officer shall perform other duties commonly
incident to his office and shall also perform such other duties and have such
other powers as the Board of Directors or the President shall designate from
time to time. The President may direct the Treasurer or any Assistant Treasurer,
or the Controller or any Assistant Controller to assume and perform the duties
of the Chief Financial Officer in the absence or disability of the Chief
Financial Officer, and each Treasurer and Assistant Treasurer and each
Controller and Assistant Controller shall perform other duties commonly incident
to his office and shall also perform such other duties and have such other
powers as the Board of Directors or the President shall designate from time to
time.

         SECTION 28. DELEGATION OF AUTHORITY. The Board of Directors may from
time to time delegate the powers or duties of any officer to any other officer
or agent, notwithstanding any provision hereof.

         SECTION 29. RESIGNATIONS. Any officer may resign at any time by giving
written notice to the Board of Directors or to the President or to the
Secretary. Any such resignation shall be effective when received by the person
or persons to whom such notice is given, unless a later time is specified
therein, in which event the resignation shall become effective at such later
time. Unless otherwise specified in such notice, the acceptance of any such
resignation shall not 


                                     13.


<PAGE>

be necessary to make it effective. Any resignation shall be without prejudice 
to the rights, if any, of the corporation under any contract with the 
resigning officer.

         SECTION 30. REMOVAL. Any officer may be removed from office at any
time, either with or without cause, by the affirmative vote of a majority of the
directors in office at the time, or by the unanimous written consent of the
directors in office at the time, or by any committee or superior officers upon
whom such power of removal may have been conferred by the Board of Directors.

                                   ARTICLE VI

      EXECUTION OF CORPORATE INSTRUMENTS AND VOTING OF SECURITIES OWNED BY
                                THE CORPORATION

         SECTION 31. EXECUTION OF CORPORATE INSTRUMENTS. The Board of Directors
may, in its discretion, determine the method and designate the signatory officer
or officers, or other person or persons, to execute on behalf of the corporation
any corporate instrument or document, or to sign on behalf of the corporation
the corporate name without limitation, or to enter into contracts on behalf of
the corporation, except where otherwise provided by law or these Bylaws, and
such execution or signature shall be binding upon the corporation.

         All checks and drafts drawn on banks or other depositaries on funds to
the credit of the corporation or in special accounts of the corporation shall be
signed by such person or persons as the Board of Directors shall authorize so to
do.

         Unless authorized or ratified by the Board of Directors or within the
agency power of an officer, no officer, agent or employee shall have any power
or authority to bind the corporation by any contract or engagement or to pledge
its credit or to render it liable for any purpose or for any amount.

         SECTION 32. VOTING OF SECURITIES OWNED BY THE CORPORATION. All stock
and other securities of other corporations owned or held by the corporation for
itself, or for other parties in any capacity, shall be voted, and all proxies
with respect thereto shall be executed, by the person authorized so to do by
resolution of the Board of Directors, or, in the absence of such authorization,
by the Chairman of the Board of Directors, the Chief Executive Officer, the
President, or any Vice President.

                                   ARTICLE VII

                                 SHARES OF STOCK

         SECTION 33. FORM AND EXECUTION OF CERTIFICATES. Certificates for the
shares of stock of the corporation shall be in such form as is consistent with
the Certificate of Incorporation and applicable law. Every holder of stock in
the corporation shall be entitled to have a certificate signed by or in the name
of the corporation by the Chairman of the Board of Directors, or the President
or any Vice President and by the Treasurer or Assistant Treasurer or the
Secretary or Assistant Secretary, certifying the number of shares owned by him
in the corporation. Any or all 


                                     14.


<PAGE>

of the signatures on the certificate may be facsimiles. In case any officer, 
transfer agent, or registrar who has signed or whose facsimile signature has 
been placed upon a certificate shall have ceased to be such officer, transfer 
agent, or registrar before such certificate is issued, it may be issued with 
the same effect as if he were such officer, transfer agent, or registrar at 
the date of issue. Each certificate shall state upon the face or back 
thereof, in full or in summary, all of the powers, designations, preferences, 
and rights, and the limitations or restrictions of the shares authorized to 
be issued or shall, except as otherwise required by law, set forth on the 
face or back a statement that the corporation will furnish without charge to 
each stockholder who so requests the powers, designations, preferences and 
relative, participating, optional, or other special rights of each class of 
stock or series thereof and the qualifications, limitations or restrictions 
of such preferences and/or rights. Within a reasonable time after the 
issuance or transfer of uncertificated stock, the corporation shall send to 
the registered owner thereof a written notice containing the information 
required to be set forth or stated on certificates pursuant to this section 
or otherwise required by law or with respect to this section a statement that 
the corporation will furnish without charge to each stockholder who so 
requests the powers, designations, preferences and relative participating, 
optional or other special rights of each class of stock or series thereof and 
the qualifications, limitations or restrictions of such preferences and/or 
rights. Except as otherwise expressly provided by law, the rights and 
obligations of the holders of certificates representing stock of the same 
class and series shall be identical.

         SECTION 34. LOST CERTIFICATES. A new certificate or certificates shall
be issued in place of any certificate or certificates theretofore issued by the
corporation alleged to have been lost, stolen, or destroyed, upon the making of
an affidavit of that fact by the person claiming the certificate of stock to be
lost, stolen, or destroyed. The corporation may require, as a condition
precedent to the issuance of a new certificate or certificates, the owner of
such lost, stolen, or destroyed certificate or certificates, or his legal
representative, to agree to indemnify the corporation in such manner as it shall
require or to give the corporation a surety bond in such form and amount as it
may direct as indemnity against any claim that may be made against the
corporation with respect to the certificate alleged to have been lost, stolen,
or destroyed.

         SECTION 35. TRANSFERS.

                  (a) Transfers of record of shares of stock of the corporation
shall be made only upon its books by the holders thereof, in person or by
attorney duly authorized, and upon the surrender of a properly endorsed
certificate or certificates for a like number of shares.

                  (b) The corporation shall have power to enter into and perform
any agreement with any number of stockholders of any one or more classes of
stock of the corporation to restrict the transfer of shares of stock of the
corporation of any one or more classes owned by such stockholders in any manner
not prohibited by the DGCL.

         SECTION 36. FIXING RECORD DATES.

                  (a) In order that the corporation may determine the
stockholders entitled to notice of or to vote at any meeting of stockholders or
any adjournment thereof, the Board of Directors may fix, in advance, a record
date, which record date shall not precede the date upon which the resolution
fixing the record date is adopted by the Board of Directors, and which 


                                     15.


<PAGE>

record date shall, subject to applicable law, not be more than sixty (60) nor 
less than ten (10) days before the date of such meeting. If no record date is 
fixed by the Board of Directors, the record date for determining stockholders 
entitled to notice of or to vote at a meeting of stockholders shall be at the 
close of business on the day next preceding the day on which notice is given, 
or if notice is waived, at the close of business on the day next preceding 
the day on which the meeting is held. A determination of stockholders of 
record entitled to notice of or to vote at a meeting of stockholders shall 
apply to any adjournment of the meeting; PROVIDED, HOWEVER, that the Board of 
Directors may fix a new record date for the adjourned meeting.

                  (b) Prior to the Initial Public Offering, in order that the
corporation may determine the stockholders entitled to consent to corporate
action in writing without a meeting, the Board of Directors may fix a record
date, which record date shall not precede the date upon which the resolution
fixing the record date is adopted by the Board of Directors, and which date
shall not be more than ten (10) days after the date upon which the resolution
fixing the record date is adopted by the Board of Directors. Any stockholder of
record seeking to have the stockholders authorize or take corporate action by
written consent shall, by written notice to the Secretary, request the Board of
Directors to fix a record date. The Board of Directors shall promptly, but in
all events within ten (10) days after the date on which such a request is
received, adopt a resolution fixing the record date. If no record date has been
fixed by the Board of Directors within ten (10) days of the date on which such a
request is received, the record date for determining stockholders entitled to
consent to corporate action in writing without a meeting, when no prior action
by the Board of Directors is required by applicable law, shall be the first date
on which a signed written consent setting forth the action taken or proposed to
be taken is delivered to the corporation by delivery to its registered office in
the State of Delaware, its principal place of business or an officer or agent of
the corporation having custody of the book in which proceedings of meetings of
stockholders are recorded. Delivery made to the corporation's registered office
shall be by hand or by certified or registered mail, return receipt requested.
If no record date has been fixed by the Board of Directors and prior action by
the Board of Directors is required by law, the record date for determining
stockholders entitled to consent to corporate action in writing without a
meeting shall be at the close of business on the day on which the Board of
Directors adopts the resolution taking such prior action.

                  (c) In order that the corporation may determine the
stockholders entitled to receive payment of any dividend or other distribution
or allotment of any rights or the stockholders entitled to exercise any rights
in respect of any change, conversion or exchange of stock, or for the purpose of
any other lawful action, the Board of Directors may fix, in advance, a record
date, which record date shall not precede the date upon which the resolution
fixing the record date is adopted, and which record date shall be not more than
sixty (60) days prior to such action. If no record date is fixed, the record
date for determining stockholders for any such purpose shall be at the close of
business on the day on which the Board of Directors adopts the resolution
relating thereto.

         SECTION 37. REGISTERED STOCKHOLDERS. The corporation shall be entitled
to recognize the exclusive right of a person registered on its books as the
owner of shares to receive dividends, and to vote as such owner, and shall not
be bound to recognize any equitable or other 


                                      16.


<PAGE>

claim to or interest in such share or shares on the part of any other person 
whether or not it shall have express or other notice thereof, except as 
otherwise provided by the laws of Delaware.

                                  ARTICLE VIII

                       OTHER SECURITIES OF THE CORPORATION

         SECTION 38. EXECUTION OF OTHER SECURITIES. All bonds, debentures and
other corporate securities of the corporation, other than stock certificates
(covered in Section 34), may be signed by the Chairman of the Board of
Directors, the President or any Vice President, or such other person as may be
authorized by the Board of Directors, and the corporate seal impressed thereon
or a facsimile of such seal imprinted thereon and attested by the signature of
the Secretary or an Assistant Secretary, or the Chief Financial Officer or
Treasurer or an Assistant Treasurer; PROVIDED, HOWEVER, that where any such
bond, debenture or other corporate security shall be authenticated by the manual
signature, or where permissible facsimile signature, of a trustee under an
indenture pursuant to which such bond, debenture or other corporate security
shall be issued, the signatures of the persons signing and attesting the
corporate seal on such bond, debenture or other corporate security may be the
imprinted facsimile of the signatures of such persons. Interest coupons
appertaining to any such bond, debenture or other corporate security,
authenticated by a trustee as aforesaid, shall be signed by the Treasurer or an
Assistant Treasurer of the corporation or such other person as may be authorized
by the Board of Directors, or bear imprinted thereon the facsimile signature of
such person. In case any officer who shall have signed or attested any bond,
debenture or other corporate security, or whose facsimile signature shall appear
thereon or on any such interest coupon, shall have ceased to be such officer
before the bond, debenture or other corporate security so signed or attested
shall have been delivered, such bond, debenture or other corporate security
nevertheless may be adopted by the corporation and issued and delivered as
though the person who signed the same or whose facsimile signature shall have
been used thereon had not ceased to be such officer of the corporation.

                                   ARTICLE IX

                                    DIVIDENDS

         SECTION 39. DECLARATION OF DIVIDENDS. Dividends upon the capital stock
of the corporation, subject to the provisions of the Certificate of
Incorporation and applicable law, if any, may be declared by the Board of
Directors pursuant to law at any regular or special meeting. Dividends may be
paid in cash, in property, or in shares of the capital stock, subject to the
provisions of the Certificate of Incorporation and applicable law.

         SECTION 40. DIVIDEND RESERVE. Before payment of any dividend, there may
be set aside out of any funds of the corporation available for dividends such
sum or sums as the Board of Directors from time to time, in their absolute
discretion, think proper as a reserve or reserves to meet contingencies, or for
equalizing dividends, or for repairing or maintaining any property of the
corporation, or for such other purpose as the Board of Directors shall think
conducive to the interests of the corporation, and the Board of Directors may
modify or abolish any such reserve in the manner in which it was created.


                                    17.


<PAGE>

                                    ARTICLE X

                                   FISCAL YEAR

         SECTION 41. FISCAL YEAR. The fiscal year of the corporation shall be
fixed by resolution of the Board of Directors.

                                   ARTICLE XI

                                 INDEMNIFICATION

         SECTION 42. INDEMNIFICATION OF DIRECTORS, EXECUTIVE OFFICERS, OTHER
OFFICERS, EMPLOYEES AND OTHER AGENTS.

                  (a) DIRECTORS AND EXECUTIVE OFFICERS. The corporation shall
indemnify its directors and executive officers (for the purposes of this Article
XI, "executive officers" shall have the meaning defined in Rule 3b-7 promulgated
under the 1934 Act) to the fullest extent not prohibited by the DGCL or any
other applicable law; PROVIDED, HOWEVER, that the corporation may modify the
extent of such indemnification by individual contracts with its directors and
executive officers; and, PROVIDED, FURTHER, that the corporation shall not be
required to indemnify any director or executive officer in connection with any
proceeding (or part thereof) initiated by such person unless (i) such
indemnification is expressly required to be made by law, (ii) the proceeding was
authorized by the Board of Directors of the corporation, (iii) such
indemnification is provided by the corporation, in its sole discretion, pursuant
to the powers vested in the corporation under the DGCL or any other applicable
law or (iv) such indemnification is required to be made under subsection (d).

                  (b) EMPLOYEES AND OTHER AGENTS. The corporation shall have
power to indemnify its other officers, employees and other agents as set forth
in the DGCL or any other applicable law. The Board of Directors shall have the
power to delegate the determination of whether indemnification shall be given to
any such person except executive officers to such officers or other persons as
the Board of Directors shall determine.

                  (c) EXPENSES. The corporation shall advance to any person who
was or is a party or is threatened to be made a party to any threatened, pending
or completed action, suit or proceeding, whether civil, criminal, administrative
or investigative, by reason of the fact that he is or was a director or
executive officer, of the corporation, or is or was serving at the request of
the corporation as a director or executive officer of another corporation,
partnership, joint venture, trust or other enterprise, prior to the final
disposition of the proceeding, promptly following request therefor, all expenses
incurred by any director or executive officer in connection with such proceeding
upon receipt of an undertaking by or on behalf of such person to repay said
amounts if it should be determined ultimately that such person is not entitled
to be indemnified under this Section 42 or otherwise.

         Notwithstanding the foregoing, unless otherwise determined pursuant to
paragraph (e) of this Section 42, no advance shall be made by the corporation to
an executive officer of the corporation (except by reason of the fact that such
executive officer is or was a director of the 


                                    18.


<PAGE>

corporation in which event this paragraph shall not apply) in any action, 
suit or proceeding, whether civil, criminal, administrative or investigative, 
if a determination is reasonably and promptly made (i) by the Board of 
Directors by a majority vote of a quorum consisting of directors who were not 
parties to the proceeding, or (ii) if such quorum is not obtainable, or, even 
if obtainable, a quorum of disinterested directors so directs, by independent 
legal counsel in a written opinion, that the facts known to the 
decision-making party at the time such determination is made demonstrate 
clearly and convincingly that such person acted in bad faith or in a manner 
that such person did not believe to be in or not opposed to the best 
interests of the corporation.

                  (d) ENFORCEMENT. Without the necessity of entering into an
express contract, all rights to indemnification and advances to directors and
executive officers under this Bylaw shall be deemed to be contractual rights and
be effective to the same extent and as if provided for in a contract between the
corporation and the director. Any right to indemnification or advances granted
by this Section 42 to a director or executive officer shall be enforceable by or
on behalf of the person holding such right in any court of competent
jurisdiction if (i) the claim for indemnification or advances is denied, in
whole or in part, or (ii) no disposition of such claim is made within ninety
(90) days of request therefor. The claimant in such enforcement action, if
successful in whole or in part, shall be entitled to be paid also the expense of
prosecuting his claim. In connection with any claim for indemnification, the
corporation shall be entitled to raise as a defense to any such action that the
claimant has not met the standards of conduct that make it permissible under the
DGCL or any other applicable law for the corporation to indemnify the claimant
for the amount claimed. In connection with any claim by a director or an
executive officer of the corporation (except in any action, suit or proceeding,
whether civil, criminal, administrative or investigative, by reason of the fact
that such executive officer is or was a director of the corporation) for
advances, the corporation shall be entitled to raise a defense as to any such
action clear and convincing evidence that such person acted in bad faith or in a
manner that such person did not believe to be in or not opposed to the best
interests of the corporation, or with respect to any criminal action or
proceeding that such person acted without reasonable cause to believe that his
conduct was lawful. Neither the failure of the corporation (including its Board
of Directors, independent legal counsel or its stockholders) to have made a
determination prior to the commencement of such action that indemnification of
the claimant is proper in the circumstances because he has met the applicable
standard of conduct set forth in the DGCL or any other applicable law, nor an
actual determination by the corporation (including its Board of Directors,
independent legal counsel or its stockholders) that the claimant has not met
such applicable standard of conduct, shall be a defense to the action or create
a presumption that claimant has not met the applicable standard of conduct.

                  (e) NON-EXCLUSIVITY OF RIGHTS. The rights conferred on any
person by this Bylaw shall not be exclusive of any other right which such person
may have or hereafter acquire under any applicable statute, provision of the
Certificate of Incorporation, Bylaws, agreement, vote of stockholders or
disinterested directors or otherwise, both as to action in his official capacity
and as to action in another capacity while holding office. The corporation is
specifically authorized to enter into individual contracts with any or all of
its directors, officers, employees or agents respecting indemnification and
advances, to the fullest extent not prohibited by the Delaware General
Corporation Law, or by any other applicable law.


                                     19.


<PAGE>

                  (f) SURVIVAL OF RIGHTS. The rights conferred on any person by
this Bylaw shall continue as to a person who has ceased to be a director,
officer, employee or other agent and shall inure to the benefit of the heirs,
executors and administrators of such a person.

                  (g) INSURANCE. To the fullest extent permitted by the DGCL or
any other applicable law, the corporation, upon approval by the Board of
Directors, may purchase insurance on behalf of any person required or permitted
to be indemnified pursuant to this Section 42.

                  (h) AMENDMENTS. Any repeal or modification of this Section 42
shall only be prospective and shall not affect the rights under this Bylaw in
effect at the time of the alleged occurrence of any action or omission to act
that is the cause of any proceeding against any agent of the corporation.

                  (i) SAVING CLAUSE. If this Bylaw or any portion hereof shall
be invalidated on any ground by any court of competent jurisdiction, then the
corporation shall nevertheless indemnify each director and executive officer to
the full extent not prohibited by any applicable portion of this Section 42 that
shall not have been invalidated, or by any other applicable law. If this Section
42 shall be invalid due to the application of the indemnification provisions of
another jurisdiction, then the corporation shall indemnify each director and
executive officer to the full extent under any other applicable law.

                  (j) CERTAIN DEFINITIONS. For the purposes of this Bylaw, the
following definitions shall apply:

                           (1) The term "proceeding" shall be broadly construed
and shall include, without limitation, the investigation, preparation,
prosecution, defense, settlement, arbitration and appeal of, and the giving of
testimony in, any threatened, pending or completed action, suit or proceeding,
whether civil, criminal, administrative or investigative.

                           (2) The term "expenses" shall be broadly construed
and shall include, without limitation, court costs, attorneys' fees, witness
fees, fines, amounts paid in settlement or judgment and any other costs and
expenses of any nature or kind incurred in connection with any proceeding.

                           (3) The term the "corporation" shall include, in
addition to the resulting corporation, any constituent corporation (including
any constituent of a constituent) absorbed in a consolidation or merger which,
if its separate existence had continued, would have had power and authority to
indemnify its directors, officers, and employees or agents, so that any person
who is or was a director, officer, employee or agent of such constituent
corporation, or is or was serving at the request of such constituent corporation
as a director, officer, employee or agent of another corporation, partnership,
joint venture, trust or other enterprise, shall stand in the same position under
the provisions of this Section 42 with respect to the resulting or surviving
corporation as he would have with respect to such constituent corporation if its
separate existence had continued.


                                     20.


<PAGE>

                           (4) References to a "director," "executive officer,"
"officer," "employee," or "agent" of the corporation shall include, without
limitation, situations where such person is serving at the request of the
corporation as, respectively, a director, executive officer, officer, employee,
trustee or agent of another corporation, partnership, joint venture, trust or
other enterprise.

                           (5) References to "other enterprises" shall include
employee benefit plans; references to "fines" shall include any excise taxes
assessed on a person with respect to an employee benefit plan; and references to
"serving at the request of the corporation" shall include any service as a
director, officer, employee or agent of the corporation which imposes duties on,
or involves services by, such director, officer, employee, or agent with respect
to an employee benefit plan, its participants, or beneficiaries; and a person
who acted in good faith and in a manner he reasonably believed to be in the
interest of the participants and beneficiaries of an employee benefit plan shall
be deemed to have acted in a manner "not opposed to the best interests of the
corporation" as referred to in this Section 42.

                                   ARTICLE XII

                                     NOTICES

         SECTION 43. NOTICES.

                  (a) NOTICE TO STOCKHOLDERS. Whenever, under any provisions of
these Bylaws, notice is required to be given to any stockholder, it shall be
given in writing, timely and duly deposited in the United States mail, postage
prepaid, and addressed to his last known post office address as shown by the
stock record of the corporation or its transfer agent.

                  (b) NOTICE TO DIRECTORS. Any notice required to be given to
any director may be given by the method stated in subsection (a), or by
overnight delivery service, facsimile, telex or telegram, except that such
notice other than one which is delivered personally shall be sent to such
address as such director shall have filed in writing with the Secretary, or, in
the absence of such filing, to the last known post office address of such
director.

                  (c) AFFIDAVIT OF MAILING. An affidavit of mailing, executed by
a duly authorized and competent employee of the corporation or its transfer
agent appointed with respect to the class of stock affected, specifying the name
and address or the names and addresses of the stockholder or stockholders, or
director or directors, to whom any such notice or notices was or were given, and
the time and method of giving the same, shall in the absence of fraud, be prima
facie evidence of the facts therein contained.

                  (d) TIME NOTICES DEEMED GIVEN. All notices given by mail or by
overnight delivery service, as above provided, shall be deemed to have been
given as at the time of mailing, and all notices given by facsimile, telex or
telegram shall be deemed to have been given as of the sending time recorded at
time of transmission.

                  (e) METHODS OF NOTICE. It shall not be necessary that the same
method of giving notice be employed in respect of all directors, but one
permissible method may be 


                                      21.


<PAGE>

employed in respect of any one or more, and any other permissible method or 
methods may be employed in respect of any other or others.

                  (f) FAILURE TO RECEIVE NOTICE. The period or limitation of
time within which any stockholder may exercise any option or right, or enjoy any
privilege or benefit, or be required to act, or within which any director may
exercise any power or right, or enjoy any privilege, pursuant to any notice sent
him in the manner above provided, shall not be affected or extended in any
manner by the failure of such stockholder or such director to receive such
notice.

                  (g) NOTICE TO PERSON WITH WHOM COMMUNICATION IS UNLAWFUL.
Whenever notice is required to be given, under any provision of law or of the
Certificate of Incorporation or Bylaws of the corporation, to any person with
whom communication is unlawful, the giving of such notice to such person shall
not be required and there shall be no duty to apply to any governmental
authority or agency for a license or permit to give such notice to such person.
Any action or meeting which shall be taken or held without notice to any such
person with whom communication is unlawful shall have the same force and effect
as if such notice had been duly given. In the event that the action taken by the
corporation is such as to require the filing of a certificate under any
provision of the DGCL, the certificate shall state, if such is the fact and if
notice is required, that notice was given to all persons entitled to receive
notice except such persons with whom communication is unlawful.

                  (h) NOTICE TO PERSON WITH UNDELIVERABLE ADDRESS. Whenever
notice is required to be given, under any provision of law or the Certificate of
Incorporation or Bylaws of the corporation, to any stockholder to whom (i)
notice of two consecutive annual meetings, and all notices of meetings or of the
taking of action by written consent without a meeting to such person during the
period between such two consecutive annual meetings, or (ii) all, and at least
two, payments (if sent by first class mail) of dividends or interest on
securities during a twelve-month period, have been mailed addressed to such
person at his address as shown on the records of the corporation and have been
returned undeliverable, the giving of such notice to such person shall not be
required. Any action or meeting which shall be taken or held without notice to
such person shall have the same force and effect as if such notice had been duly
given. If any such person shall deliver to the corporation a written notice
setting forth his then current address, the requirement that notice be given to
such person shall be reinstated. In the event that the action taken by the
corporation is such as to require the filing of a certificate under any
provision of the DGCL, the certificate need not state that notice was not given
to persons to whom notice was not required to be given pursuant to this
paragraph.

                                  ARTICLE XIII

                                   AMENDMENTS

         SECTION 44. AMENDMENTS. Subject to paragraph (h) of Section 42 of the
Bylaws, the Bylaws may be altered or amended or new Bylaws adopted by the
affirmative vote of at least sixty-six and two-thirds percent (66-2/3%) of the
voting power of all of the then-outstanding shares of the voting stock of the
corporation entitled to vote. The Board of Directors shall also have the power
to adopt, amend, or repeal Bylaws.


                                     22.


<PAGE>

                                   ARTICLE XIV

                                LOANS TO OFFICERS

         SECTION 45. LOANS TO OFFICERS. The corporation may lend money to, or
guarantee any obligation of, or otherwise assist any officer or other employee
of the corporation or of its subsidiaries, including any officer or employee who
is a Director of the corporation or its subsidiaries, whenever, in the judgment
of the Board of Directors, such loan, guarantee or assistance may reasonably be
expected to benefit the corporation. The loan, guarantee or other assistance may
be with or without interest and may be unsecured, or secured in such manner as
the Board of Directors shall approve, including, without limitation, a pledge of
shares of stock of the corporation. Nothing in these Bylaws shall be deemed to
deny, limit or restrict the powers of guaranty or warranty of the corporation at
common law or under any statute.

                                   ARTICLE XV

                            TRANSFERS OF COMMON STOCK

         SECTION 46. PROHIBITION OF TRANSFERS. No holder of Common Stock (other
than Common Stock acquired upon conversion of Preferred Stock) of the Company
shall or transfer any shares of Common Stock of the Company except in accordance
with this Article XV.

         SECTION 47. EXEMPT TRANSFERS. The prohibition of transfers set forth in
Section 47 above shall not apply to (a) any pledge made by a holder of Common
Stock pursuant to a bona fide secured loan transaction, (b) any transfer by a
holder of Common Stock to his ancestors or descendants or spouse or to a trustee
for their benefit, (c) any transfer by a holder of Common Stock to his own
individual retirement account, (d) any transfer by a holder of Common Stock for
estate planning purposes, (e) any bona fide gift by a holder of Common Stock, or
(f) any sale or transfer of Common Stock which was issued upon conversion of
Preferred Stock. Any such transfer referred to in this Section 47 shall be
hereinafter referred to as a "Permitted Transfer."

         SECTION 48. NOTICE. In the event any holder of Common Stock (other than
Common Stock acquired upon conversion of Preferred Stock) of the Company (the
"Selling Common Stockholder") proposes to transfer, other than a Permitted
Transfer, or proposes to accept one or more bona fide offers (collectively, a
"Common Stock Purchase Offer') from any persons to purchase shares of Common
Stock from the Selling Common Stockholder, then the Selling Common Stockholder
shall promptly notify the Company of the terms and conditions of such Common
Stock Purchase Offer.

         SECTION 49. RIGHT OF FIRST REFUSAL. The Company or its assignee shall
have the right, exercisable upon written notice to the Selling Common
Stockholder within fifteen (15) days after receipt of the notice required under
Section 47 above (the "Company Notice"), to purchase from the Selling Common
Stockholder some or all of the shares of Common Stock offered pursuant to and
under the same terms and conditions specified in such Common Stock Purchase
Offer. The right of the Company shall be subject to the following terms and
conditions:


                                    23.


<PAGE>

                  (a) In the event the Company elects to acquire the Common
Stock as specified in the notice required under Section 47 above, the Company
shall so notify the Selling Common Stockholder and settlement thereof shall be
made in cash within five (5) days after the Selling Common Stockholder receives
notice of the Company's election to purchase such Common Stock; provided,
however, that if the terms of payment set forth in the Company Notice were other
than cash against delivery or promissory notes payable over time, the Company
shall pay the fair market value of such Common Stock as determined by the
Company's Board of Directors, which determination shall be final. The Selling
Common Stockholder shall deliver his stock certificate(s) to the Company with a
duly executed assignment thereof (in blank) on or prior to such settlement date
for transfer to the Company.

                  (b) If the Company elects not to purchase, or is unable to
purchase, some or all of the Shares specified in the Company Notice, the Selling
Common Stockholder may sell the Common Stock, subject to the restrictions set
forth in the Co-Sale Agreement entered into by and among the Company and certain
holders of the Company's Stock and Preferred Stock, to any person named in the
Company Notice upon terms and conditions no more favorable to the purchasers
than the terms specified in such notice, provided that such sale or transfer is
consummated within sixty (60) days from the date of the Company Notice, and
provided, further, that any such sale is in accordance with all the terms and
conditions hereof. Notwithstanding the foregoing, the Selling Common Stockholder
may not transfer Shares to any party whom the Company reasonably determines is a
competitor or potential competitor of the Company or to any party whom the
Company's Board of Director reasonably believes would have an adverse effect
upon the Company is such party were to become a shareholder of the Company.

         SECTION 50. EXPIRATION. The restrictions on transfer set forth in this
Article XV shall expire upon the closing of the Initial Public Offering.


                                      24.




<PAGE>

NUMBER                          INCORPORATED UNDER                     SHARES
*________*                THE LAWS OF THE STATE OF DELAWARE          *________*
                               ON JANUARY 16, 1997


                           ACADIA PHARMACEUTICALS INC.
                                  COMMON STOCK


                                     [SEAL]

THIS CERTIFIES THAT _______________ IS THE REGISTERED HOLDER OF _____________
(______) SHARES OF THE COMMON STOCK OF ACADIA PHARMACEUTICALS INC. TRANSFERABLE
ONLY ON THE BOOKS OF THE CORPORATION BY THE HOLDER HEREOF, IN PERSON OR BY DULY
AUTHORIZED ATTORNEY, UPON SURRENDER OF THIS CERTIFICATE PROPERLY ENDORSED OR
ASSIGNED.

A STATEMENT OF THE RIGHTS, PREFERENCES, PRIVILEGES AND RESTRICTIONS GRANTED TO
OR IMPOSED UPON THE RESPECTIVE CLASSES OR SERIES OF SHARES OF STOCK OF THE
CORPORATION AND UPON HOLDERS THEREOF AS ESTABLISHED BY THE CERTIFICATE OF
INCORPORATION, AND THE NUMBER OF SHARES CONSTITUTING EACH SERIES AND THE
DESIGNATIONS THEREOF, MAY BE OBTAINED BY ANY STOCKHOLDER UPON REQUEST AND
WITHOUT CHARGE AT THE PRINCIPAL OFFICE OF THE CORPORATION.

IN WITNESS WHEREOF, THE CORPORATION HAS CAUSED THIS CERTIFICATE TO BE SIGNED 
BY ITS DULY AUTHORIZED OFFICERS THIS ________ DAY OF ________ 20__.

________________                                             _________________
THOMAS H. AASEN                                              MARK R. BRANN
SECRETARY                                                    PRESIDENT

[SEAL]                                SHARES
                                       EACH


<PAGE>

FOR VALUE RECEIVED, _______________HEREBY SELL, ASSIGN AND TRANSFER UNTO ______
______________________________________________________________________________
____________________, SHARES OF THE COMMON STOCK OF THE WITHIN NAMED 
CORPORATION, REPRESENTED BY THE WITHIN CERTIFICATE
 AND DO HEREBY IRREVOCABLY 
CONSTITUTE AND APPOINT___________________________________________ ATTORNEY TO 
TRANSFER THE SAID SHARES OF SAID COMMON STOCK ON THE BOOKS OF THE SAID 
CORPORATION, PURSUANT TO THE PROVISIONS OF THE BY-LAWS THEREOF, WITH FULL 
POWERS OF SUBSTITUTION IN THE PREMISES.

                        DATED________________________________________A.D.
                             ____________________________________________

IN PRESENCE OF:
______________________________________________________

NOTICE: THE SIGNATURE TO THIS ASSIGNMENT MUST STRICTLY CORRESPOND WITH THE 
NAME AS WRITTEN UPON THE FACE OF THE CERTIFICATE IN EVERY PARTICULAR AND 
WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATEVER.




<PAGE>


                           ACADIA PHARMACEUTICALS INC.


                ________________________________________________



                   AMENDED AND RESTATED STOCKHOLDERS AGREEMENT


                ________________________________________________



                                   MAY 5, 2000




<PAGE>

                                                   TABLE OF CONTENTS


<TABLE>
<CAPTION>

                                                                                                               PAGE
<S>                                                                                                            <C>
ARTICLE 1         DEFINITIONS.....................................................................................2

ARTICLE 2         RIGHT OF FIRST REFUSAL..........................................................................2

         2.1      Generally.......................................................................................2

         2.2      Acceptance......................................................................................3

         2.3      Sale by Company.................................................................................3

         2.4      Decrease in Shares Sold.........................................................................3

         2.5      Purchase of Shares..............................................................................4

         2.6      Shares not Sold.................................................................................4

         2.7      Exclusions from First Refusal Right.............................................................4

         2.8      Applicability of this Agreement to Offered Securities...........................................5

ARTICLE 3         RESTRICTIONS ON TRANSFER........................................................................5

         3.1      Generally.......................................................................................5

         3.2      [Intentionally Omitted].........................................................................5

         3.3      Permitted Transfers.............................................................................5

         3.4      Offer for Sale; Notice of Proposed Sale.........................................................6

         3.5      Option to Purchase..............................................................................6

         3.6      Sale to Offerer; Closing........................................................................7

         3.7      Co-Sale Rights..................................................................................8

         3.8      Treatment of Sale Proceeds......................................................................8

ARTICLE 4         COME-ALONG OBLIGATIONS..........................................................................8

         4.1      Generally.......................................................................................8

         4.2      Notice..........................................................................................9

         4.3      Closing.........................................................................................9

         4.4      Stock Options..................................................................................10

ARTICLE 5         EVENTS OF DEFAULT..............................................................................10

         5.1      Events of Default..............................................................................10

         5.2      Remedies on Default............................................................................11

         5.3      Notice of Default..............................................................................11

         5.4      Specific Enforcement...........................................................................11

         5.5      Remedies not Waived............................................................................11


                                                         i.


<PAGE>

                                                   TABLE OF CONTENTS
                                                     (CONTINUED)

ARTICLE 6         GOVERNANCE.....................................................................................12

         6.1      Composition of the Board.......................................................................12

         6.2      Frequency, Quorum and Voting...................................................................13

         6.3      Notice of Meetings.............................................................................13

         6.4      Special Meetings...............................................................................13

         6.5      Composition of Committees......................................................................13

         6.6      Governance of Subsidiaries.....................................................................13

         6.7      Stockholders' Obligations to Take Certain Actions..............................................13

         6.8      Limitation
 on Directors' Actions...............................................................13

ARTICLE 7         AFFIRMATIVE COVENANTS OF THE COMPANY...........................................................14

         7.1      Material Changes and Litigation................................................................14

         7.2      Transactions with Affiliates...................................................................14

         7.3      Board Observer.................................................................................14

         7.4      Corporate Existence............................................................................14

         7.5      Financial Statements and Other Information.....................................................14

         7.6      Inspection of Books and Records................................................................15

         7.7      Payment of Taxes...............................................................................15

         7.8      Insurance......................................................................................15

         7.9      Patents and Intellectual Property..............................................................15

         7.10     Nondisclosure Agreements.......................................................................16

         7.11     Expenses and Compensation of Directors.........................................................16

         7.12     Reservation of Common Stock....................................................................16

         7.13     International Investment and Trade in Services Survey Act......................................16

         7.14     Copenhagen Lead Discovery Project..............................................................16

         7.15     Notice of Certain Breaches.....................................................................16

         7.16     Budgets........................................................................................16

         7.17     Conduct of Business............................................................................16

         7.18     Preservation of Shares.........................................................................16

ARTICLE 8         NEGATIVE COVENANTS.............................................................................17

ARTICLE 9         REGISTRATION RIGHTS............................................................................17


                                                         ii.


<PAGE>

                                                   TABLE OF CONTENTS
                                                     (CONTINUED)

         9.1      Required Registrations.........................................................................17

         9.2      Incidental Registration........................................................................18

         9.3      Registration Procedures........................................................................19

         9.4      Allocation of Expenses.........................................................................20

         9.5      Indemnification and Contribution...............................................................21

         9.6      Indemnification With Respect to Underwritten Offering..........................................23

         9.7      Information by Holder..........................................................................23

         9.8      "Stand-Off" Agreement..........................................................................23

         9.9      Rule 144 Requirements..........................................................................23

         9.11     Termination of Registration Rights.............................................................24

         9.12     Transfers of Rights............................................................................24

         9.13     Registration Rights to Third Parties...........................................................24

         9.14     Construction...................................................................................24

ARTICLE 10        DEFINITIONS....................................................................................25

ARTICLE 11        GENERAL PROVISIONS.............................................................................31

         11.1     Legends........................................................................................31

         11.2     Amendment; Termination.........................................................................32

         11.3     Effect of Agreement............................................................................32

         11.4     Computation of Percentages or Pro Rata Share...................................................32

         11.5     Counterparts...................................................................................32

         11.6     Notices........................................................................................32

         11.7     Entire Agreement...............................................................................32

         11.8     Governing Law..................................................................................33

         11.9     Severability...................................................................................33

         11.10    Construction...................................................................................33

         11.11    Arbitration....................................................................................33
</TABLE>


                                                       iii.


<PAGE>


                           ACADIA PHARMACEUTICALS INC.

                   AMENDED AND RESTATED STOCKHOLDERS AGREEMENT


         THIS AMENDED AND RESTATED STOCKHOLDERS AGREEMENT is entered into as of
May 5, 2000, by and among ACADIA PHARMACEUTICALS INC., a Delaware corporation
(the "Company"), those individuals and entities identified on the signature page
hereof as the "Existing Institutional Stockholders" (individually, each an
"Existing Institutional Stockholder" and collectively, the "Existing
Institutional Stockholders"), MARK R. BRANN (the "Founding Stockholder") and the
entities identified on the signature page hereof as the "New Institutional
Stockholders" (individually, each a "New Institutional Stockholder" and
collectively, the "New Institutional Stockholders"). Each of the Existing
Institutional Stockholders and New Institutional Stockholders are sometimes
referred to herein as an "Institutional Stockholder" or collectively as
"Institutional Stockholders." Each of the Institutional Stockholders and the
Founding Stockholder are sometimes referred to as "Stockholder" and are
collectively referred to as the "Stockholders."

                                    RECITALS

         A. The parties to this Agreement are the Company and certain holders of
the issued and outstanding capital stock of the Company.

         B. The Company, the Founding Stockholder and the First Institutional
Stockholders entered into a Stockholders Agreement, dated as of February 3, 1997
(the "First Stockholders Agreement") in connection with the purchase and sale of
Series A Preferred Stock of the Company.

         C. On August 12, 1997 the parties to the First Stockholders Agreement
and the Partnership amended the First Stockholders Agreement (the "First Amended
Stockholders Agreement") in connection with the purchase and sale of the Series
B Preferred Stock of the Company.

         D. On September 24, 1997, the parties to the First Amended Stockholders
Agreement amended the First Amended Stockholders Agreement (the "Second Amended
Stockholders Agreement") in connection with the Company's sale of Series C
Preferred Stock to Vision Pharmaceuticals L.P.

         E. On August 26, 1998, the Parties to this Agreement other than the New
Institutional Investors amended the Second Amended Stockholders Agreement (the
"Third Amended Stockholders Agreement") in connection with the purchase and sale
of the Series D Preferred Stock of the Company.

         F. In connection with the issuance and sale of Series E Preferred Stock
by the Company, the parties to the Third Amended Stockholders Agreement and the
New Institutional Investors wish to amend and restate the Third Amended
Stockholders Agreement.


                                       1.


<PAGE>

         G. Certain of the Existing Institutional Stockholders own shares of
Series A Preferred Stock of the Company, certain of the Existing Institutional
Stockholders own shares of Series B Preferred Stock of the Company, certain of
the Existing Institutional Stockholders own Shares of Series D Preferred Stock
of the Company, and certain of the Existing Institutional Stockholders and New
Institutional Stockholders own shares of Series E Preferred Stock of the
Company. Certain of the Stockholders also hold warrants to purchase Common Stock
of the Company. The Founding Stockholder and certain of the Existing
Institutional Stockholders own shares of Common Stock.

         H. The Stockholders believe that it is in the best interests of the
Company and the Stockholders to (i) provide that Stock shall be transferable
only upon compliance with the terms hereof; (ii) provide certain registration
rights to the Existing Institutional Stockholders and the New Institutional
Stockholders; and (iii) set forth their agreements on certain other matters.

         NOW, THEREFORE, the parties hereto agree as follows:

                                    ARTICLE 1

                                   DEFINITIONS

         Capitalized terms used herein shall have those meanings ascribed to
them in Article 10 of this Agreement.

                                    ARTICLE 2

                             RIGHT OF FIRST REFUSAL

         2.1 GENERALLY. Subject to Section 2.7 below, the Company shall not
issue, sell or exchange, agree to issue, sell or exchange, or reserve or set
aside for issuance, sale or exchange, (i) any Stock, (ii) any other equity
securities of the Company, (iii) any option, warrant or other right to subscribe
for, purchase or otherwise acquire any equity securities of the Company, or (iv)
any debt securities convertible into capital stock of the Company (collectively,
unless excluded by Section 2.7 below, the "Offered Securities"), unless in each
such case the Company shall have first complied with this Agreement. The Company
shall deliver to each Stockholder a written notice of any proposed or intended
issuance, sale or exchange of Offered Securities (the "Offer"), which Offer
shall (i) identify and describe the Offered Securities, (ii) describe the price
and other terms upon which they are to be issued, sold or exchanged, and the
number or amount of the Offered Securities to be issued, sold or exchanged,
(iii) identify the persons or entities to which or with which the Offered
Securities are to be offered, issued, sold or exchanged, and (iv) offer to issue
and sell to or exchange with such Stockholder (A) such portion of the Offered
Securities as the aggregate number of shares of the Common Stock of such
Stockholder (treating, for this purpose, any outstanding convertible capital
stock on an "as converted" basis and, with respect to any outstanding Preferred
Stock, taking into account that number of shares of Preferred Stock to which
that Stockholder would be entitled following the declaration and issuance of the
"Special Dividend" as set forth in the Certificate) bears to the total number of
shares of Common Stock outstanding (after giving effect to such conversion and
dividend) (the "Basic Amount"), and (B) any additional portion of the Offered
Securities as such Stockholder 


                                      2.


<PAGE>

shall indicate it will purchase or acquire should the other Stockholders 
subscribe for less than their Basic Amounts (the "Undersubscription Amount"), 
PROVIDED that the Undersubscription Amount shall be subject to reduction as 
set forth in Section 2.2 below. Each Stockholder shall have the right, for a 
period of forty-five (45) days following delivery of the Offer, to purchase 
or acquire, at a price and upon other terms specified in the Offer, the 
number of Offered Securities described above. The Offer by its term shall 
remain open and irrevocable for such forty-five (45) day period.

         2.2 ACCEPTANCE. To accept an Offer, in whole or in part, a Stockholder
must deliver a written notice to the Company prior to the end of the forty-five
(45) day period of the Offer, setting forth the portion of the Stockholder's
Basic Amount that the Stockholder elects to purchase and, if the Stockholder
shall elect to purchase all of its Basic Amount, the Undersubscription Amount
(if any) that the Stockholder elects to purchase (the "Notice of Acceptance").
If the Basic Amounts subscribed for by all Stockholders are less than the total
Offered Securities, then any Stockholder who has set forth Undersubscription
Amounts in its Notice of Acceptance shall be entitled to purchase, in addition
to the Basic Amounts subscribed for, all Undersubscription Amounts it has
subscribed for; PROVIDED, HOWEVER, that should the Undersubscription Amounts
subscribed for exceed the difference between the Offered Securities and the
Basic Amounts subscribed for (the "Available Undersubscription Amount"), each
Stockholder who has subscribed for any Undersubscription Amount shall be
entitled to purchase only that portion of the Available Undersubscription Amount
as the Undersubscription Amount subscribed for by such Stockholder bears to the
total Undersubscription Amounts subscribed for by all Stockholders, subject to
rounding by the Board of Directors to the extent it reasonably deems necessary.

         2.3 SALE BY COMPANY. In the event that Notices of Acceptance are not
given by Stockholders in respect of all the Offered Securities, the Company
shall have up to 120 days from the expiration of the period set forth in Section
2.1 above to issue, sell or exchange all or any part of such Offered Securities
as to which a Notice of Acceptance has not been given by the Stockholders (the
"Refused Securities"), but only to one or more of the offerees or purchasers
described in the Offer and only upon terms and conditions (including, without
limitation, unit prices and interest rates) which are not more favorable, in the
aggregate, to the acquiring person or persons or less favorable to the Company
than these set forth in the Offer.

         2.4 DECREASE IN SHARES SOLD. In the event the Company shall propose to
sell less than all the Refused Securities (any such sale to be in the manner and
on the terms specified in Section 2.3 above), then each Stockholder may, at its
sole option and in its sole discretion, reduce the number or amount of the
Offered Securities specified in its Notice of Acceptance to an amount that shall
be not less than the number or amount of the Offered Securities that the
Stockholders elected to purchase pursuant to Section 2.2 above multiplied by a
fraction, (i) the numerator of which shall be the reduced number or amount of
Offered Securities the Company proposes to issue, sell or exchange (including
Offered Securities to be issued or sold to Stockholders pursuant to Section 2.2
above prior to such reduction) and (ii) the denominator of which shall be the
amount of all Offered Securities. In the event that any Stockholder so elects to
reduce the number or amount of Offered Securities specified in its Notice of
Acceptance, the Company may not issue, sell or exchange more than the reduced
number or amount of the 


                                     3.


<PAGE>

Offered Securities unless and until such securities have again been offered 
to the Stockholders in accordance with Section 2.1 above.

         2.5 PURCHASE OF SHARES. Upon the closing of the issuance, sale or
exchange of all or less than all the Refused Securities, the Stockholders shall
acquire from the Company, and the Company shall issue to the Stockholders, the
number or amount of Offered Securities specified in the Notices of Acceptance,
as reduced pursuant to Section 2.4 above if the Stockholders have so elected,
upon the terms and conditions specified in the Offer. The purchase by the
Stockholders of any Offered Securities is subject in all cases to the
preparation, execution and delivery by the Company and each Stockholder of a
purchase agreement relating to such Offered Securities reasonably satisfactory
in form and substance to each Stockholder and their respective counsel.

         2.6 SHARES NOT SOLD. Any Offered Securities not acquired by the
Stockholders or other persons in accordance with Section 2.3 above may not be
issued, sold or exchanged until they are again offered to the Stockholders under
the procedures specified in this Agreement.

         2.7 EXCLUSIONS FROM FIRST REFUSAL RIGHT. The rights of the Stockholders
under Sections 2.1 through 2.6, inclusive, shall not apply to, and the
securities described shall not be deemed "Offered Securities" for:

                  (a) Common Stock issued as a stock dividend to holders of
Common Stock or upon any subdivision or combination of shares of Common Stock;

                  (b) the issuance of any shares of Stock to holders of
Preferred Stock, pursuant to the provisions of the Certificate;

                  (c) the issuance of shares of Common Stock, or options
exercisable therefor, including options outstanding on the date of this
Agreement (as such number may be proportionately adjusted in the event of any
stock splits, stock dividends, recapitalization or similar events occurring on
or after the date of this Agreement) issued or issuable to employees, officers
or directors of, or consultants or advisers to the Company pursuant to stock
purchase or stock option plans or similar arrangements approved by the Board of
Directors;

                  (d) the issuance of Common Stock pursuant to the exercise of
Warrants outstanding as of the date hereof;

                  (e) securities issued solely in consideration for the
acquisition (whether by merger or otherwise) by the Company or any of its
subsidiaries of all or substantially all of the stock or assets of any other
entity;

                  (f) shares of Common Stock sold by the Company in an
underwritten public offering pursuant to an effective registration statement
under the Securities Act, resulting in at least Seven Million Five Hundred
Thousand United States Dollars (US$7,500,000) of gross proceeds to the Company
at a minimum price of seven dollars and 50 cents ($7.50) per share (subject to
appropriate adjustment for stock splits, stock dividends, recapitalizations and
other similar events) (a "Qualifying IPO");


                                      4.


<PAGE>

                  (g) securities issued in connection with bona fide strategic
transactions involving the Company and other entities, including (i) joint
ventures, manufacturing, marketing or distribution arrangements or (ii)
collaboration or technology transfer arrangements; PROVIDED that each such
strategic transaction and the issuance of shares pursuant thereto, has been
approved by the Board of Directors and the arrangement involves diligence
obligations (if applicable);

                  (h) securities issued in connection with the Company entering
into an equipment leasing arrangement or debt financing from a bank or similar
financial institution; PROVIDED, HOWEVER, that such issuances shall not exceed
or be exercisable for or convertible into more than an aggregate of 25,000
shares of capital stock of the Company (subject to appropriate adjustment for
stock splits, stock dividends, recapitalizations and other similar events); or

                  (i) shares of Series E Preferred Stock purchased under the
Series E Stock Purchase Agreement.

         2.8 APPLICABILITY OF THIS AGREEMENT TO OFFERED SECURITIES. No issuance
or sale of Offered Securities shall be valid unless the purchaser of such
Securities shall have executed and delivered a counterpart of this Agreement.
Offered Securities issued, sold or exchanged pursuant to this Agreement,
including those to which Section 2.7(a), (b), (d) and (e) of this Agreement is
applicable, shall be subject to the terms of this Agreement, PROVIDED, HOWEVER,
that shares of Common Stock which are the subject to the Company's 1997 Stock
Option Plan shall not be subject to this Agreement.

                                    ARTICLE 3

                            RESTRICTIONS ON TRANSFER

         3.1 GENERALLY. Any sale or other disposition of any of the shares of
Stock by a Stockholder, other than according to the terms of this Agreement,
shall be void and transfer no right, title or interest in or to any of such
shares of Stock to the purported transferee. Moreover, no transfers shall be
valid unless and until the transferee shall have executed and delivered a
counterpart of this Agreement.

         3.2 [INTENTIONALLY OMITTED].

         3.3 PERMITTED TRANSFERS. Subject to Section 3.1 of this Agreement, (a)
a Stockholder may sell, assign or transfer, without compliance with Sections 3.4
through 3.6 of this Agreement, any or all of his shares of Stock to an Affiliate
of such Stockholder or to his spouse or children or to a trust established for
the benefit of his spouse, children or himself, or dispose of them under his
will or pursuant to a judicial decree or order (PROVIDED that, in each such
case, the Company receives written notice of such transfer, that this Agreement
shall be binding upon each such transferee and, prior to the completion of such
transfer, each transferee or his or her legal representative shall have executed
documents assuming the obligations of the transferring Stockholder under this
Agreement with respect to the transferred shares). Notwithstanding the
foregoing, in the event of any sale, assignment or transfer pursuant to this
Section 3.3 the transferor and the transferee(s) shall be jointly and severally
liable as one 


                                      5.


<PAGE>

Stockholder pursuant to this Agreement. The pledge of any shares of Stock 
shall be permitted only with the approval of the Board of Directors, in its 
sole discretion.

         3.4 OFFER FOR SALE; NOTICE OF PROPOSED SALE. If any Stockholder (the
"Transferring Party") desires to sell, transfer or otherwise dispose of any of
his shares of Stock, or of any interest in such shares of Stock, whether
voluntarily or by operation of law, in any transaction other than pursuant to
Section 3.3 of this Agreement, such Transferring Party shall first deliver
written notice of such desire to do so (the "Notice") to the other Stockholders
and the Company (such other Stockholders referred to herein as the
"Non-Transferring Parties"), in each case in the manner prescribed in Section
11.6 of this Agreement. The Notice shall specify: (i) the name and address of
the party to which the Transferring Party proposes to sell or otherwise dispose
of the Stock or interest in the Stock (the "Offerer"), (ii) the number of shares
of Stock the Transferring Party proposes to sell or otherwise dispose of (the
"Shares Proposed for Transfer"), (iii) the consideration per share of Stock
offered by the Offerer to the Transferring Party for the proposed sale, transfer
or disposition, and (iv) all other material terms and conditions of the proposed
transaction. The Notice shall be accompanied by a copy of the offer from the
Offerer to the Transferring Party or such other evidence of the offer that is
reasonably satisfactory to the Transferring Parties.

         3.5 OPTION TO PURCHASE.

                  (a) The Stockholders and the Company shall have the option to
purchase all but not less than all of the Shares Proposed for Transfer. The
Stockholders shall have the first option (the "First Option") to purchase all or
any part of the Shares Proposed for Transfer for the consideration per share and
on the terms and conditions specified in the Notice. The First Option must be
exercised no later than forty-five (45) days after such Notice is deemed under
Section 11.6 hereof to have been delivered. The Stockholders shall have a right
to purchase the Shares Proposed for Transfer on a pro rata basis according to
the number of shares of Stock owned by such Stockholders. Such option shall be
exercised by delivery of written notice to the Secretary of the Company.

                  (b) In the event options to purchase have been exercised by
the Non-Transferring Parties with respect to some but not all of the Shares
Proposed for Transfer, those Non-Transferring Parties who have exercised their
options within the forty-five (45) day period specified in Section 3.5(a) shall
have an additional option, for a period of fifteen (15) days next succeeding the
expiration of such forty-five (45) day period, to purchase all or any part of
the balance of such Shares Proposed for Transfer on the terms and conditions set
forth in the Notice, which option shall be exercised by the delivery of written
notice to the Secretary of the Company. In the event there are two or more such
Non-Transferring Parties that choose to exercise the last-mentioned option for a
total number of shares of Stock in excess of the number available, the shares of
Stock available for each such Non-Transferring Party's option shall be allocated
pro rata based on the number of shares of Stock owned by the Non-Transferring
Parties so electing.

                  (c) In the event the Non-Transferring Parties do not exercise
their option with respect to all of the Shares Proposed for Transfer within such
fifteen (15) day period, the Company may elect within eight (8) days succeeding
the expiration of such fifteen (15) day 


                                      6.


<PAGE>

period, to purchase the Shares Proposed for Transfer not purchased by the 
Stockholders (the "Remaining Shares"). In such case the Company shall deliver 
written notice of such purchase to the Transferring Party.

                  (d) If the options to purchase the Shares Proposed for
Transfer are exercised in full by the Non-Transferring Parties and/or the
Company, the Secretary of the Company shall immediately notify all of the
exercising Non-Transferring Parties of that fact.

                  (e) In the event the Non-Transferring Parties and/or the
Company duly exercise their option to purchase the Shares Proposed for Transfer,
the closing of such purchase shall take place at the offices of the Company on a
single date agreed to among such purchasers, which date shall be not later than
sixty (60) days after the expiration of the applicable relevant period pursuant
to Section 3.5(a)-(c) above.

                  (f) To the extent that the consideration proposed to be paid
by the Offerer for the Shares Proposed for Transfer consists of property other
than cash or a promissory note, the consideration required to be paid by the
Company and/or the Non-Transferring Parties exercising their option to purchase
may consist of cash equal to the value of such property, as determined in good
faith by agreement of the Transferring Party and the Company and/or the
Non-Transferring Parties acquiring such Shares Proposed for Transfer. In the
event that the parties are not able to determine the value of such property, the
value of such property shall be determined by a panel of three appraisers whose
decision shall be final and binding on the parties hereto. The Transferring
Party shall choose one appraiser; the Company and/or the Non-Transferring
Parties acquiring such Shares Proposed for Transfer shall choose the second
appraiser; and the two so selected shall select and designate a third appraiser.
The value of the property shall be equal to the average of the values determined
by the three appraisers.

                  (g) Notwithstanding anything to the contrary herein, neither
the Company nor any of the Non-Transferring Parties shall have any right to
purchase any of the Shares Proposed for Transfer hereunder unless the Company
and/or the Non-Transferring Parties exercise their option or options to purchase
all of the Shares Proposed for Transfer.

                  (h) Notwithstanding anything to the contrary set forth herein,
in the event the Stockholder proposing to transfer its shares is an
Institutional Stockholder, the Company's right to purchase any or all of the
Shares Proposed for Transfer shall be conditioned upon the receipt by the
proposed selling Stockholder of either a satisfactory ruling from the relevant
taxing authority or a satisfactory option of legal counsel by such Stockholder
to the effect that the tax treatment of the proceeds on the sale of the Shares
Proposed for Transfer is not materially more adverse to the Stockholder if such
shares of Stock are purchased by the Company than would be the case if such
shares of Stock were purchased by the Offerer.

         3.6 SALE TO OFFERER; CLOSING. If the Company and/or the
Non-Transferring Parties do not exercise their options to purchase all of the
Shares Proposed for Transfer within the periods described in this Agreement (the
"Option Period"), then all options of the Company and the Non-Transferring
Parties to purchase such Shares Proposed for Transfer, whether exercised or not,
shall terminate and, subject to the provisions in Section 3.1, the Transferring
Party may sell, on the terms and conditions set forth in the Notice, the Shares
Proposed for Transfer to the Offerer, 


                                      7.


<PAGE>

PROVIDED that the transaction contemplated by the Notice shall be consummated 
not later than ninety (90) days after the expiration of the Option Period.

         3.7 CO-SALE RIGHTS. Upon the proposed occurrence of a Co-Sale
Transaction, any one or more of the Stockholders may demand that the
effectiveness of the Co-Sale Transaction be conditioned upon the right of such
Stockholder(s) to sell to the Person acquiring shares of Stock or other
securities of the Company (the "Co-Sale Purchaser") all or any part of such
Stockholder(s)' shares of Stock and other securities of the Company (a
"Co-Sale"), PROVIDED that such Stockholder(s) deliver(s) written notice to the
Stockholder transferring shares of Stock or other Company securities to the
Co-Sale Purchaser of such demand stating the number and kind of shares of Stock
and other securities it so wishes to sell within forty-five (45) days after
having received notice from the Transferring Party that a proposed sale of
shares of Stock would constitute a Co-Sale Transaction. The price for such
Stockholder(s)' shares of Stock and other securities of the Company shall be
equal to the per share price to be paid in the Co-Sale Transaction PROVIDED,
HOWEVER, that any such Stockholder and/or Transferring Party may demand that
proceeds from the Co-Sale Transaction be reallocated among such Stockholders and
the Transferring Party such that such Stockholders and the Transferring Party
shall be entitled to receive such portion of the proceeds as if the proceeds
were distributed pursuant to Section C.2.a. of Article IV of the Certificate and
PROVIDED FURTHER that such Stockholders and/or Transferring Party who tenders
securities which represent the right to purchase shares shall be entitled to
receive as consideration therefor the value of such shares (determined on the
basis of the terms and conditions applicable to the Co-Sale Transaction taking
into account the reallocation of the purchase price as aforesaid) purchasable on
the basis thereof less the exercise price, if any, of the applicable security.
The closing of the Co-Sale shall take place concurrently with the sale by the
Transferring Party to the Co-Sale Purchaser. If the Co-Sale Purchaser is
unwilling or unable to purchase all of the shares of Stock and other securities
such Stockholder(s) desire(s) to sell, neither the Company nor any Stockholder,
including the Transferring Party, shall enter into the Co-Sale Transaction. The
occurrence of a Co-Sale Transaction other than in connection with the purchase
of all of such Stockholder(s) tendered shares of Stock and other securities
shall be an Event of Default under this Agreement.

         3.8 TREATMENT OF SALE PROCEEDS. The proceeds of any sale made by any
Transferring Party without compliance with the provisions of this Article 3
shall be deemed to be held in constructive trust in such amount as would have
been due to the Stockholders desiring to sell shares of Stock or other
securities if the Transferring Party had complied with this Agreement.

                                    ARTICLE 4

                             COME-ALONG OBLIGATIONS

         4.1 GENERALLY. Each of the Stockholders (the "Participating 
Sellers") hereby agrees, if requested by a Significant Number of Stockholders 
(the Stockholders constituting such Significant Number of Stockholders are 
hereinafter referred to as the "Come-Along Stockholders"), to sell all of his 
or her shares of Stock and other securities of the Company to any other 
Person (the "Proposed Buyer") in the manner and on the terms set forth in 
this Article 4 in connection with the sale by the Come-Along Stockholders to 
the Proposed Buyer of all of 

                                     8.


<PAGE>

the shares and other securities of the Company of the Come-Along 
Stockholders. Notwithstanding the foregoing, the provisions of this Article 4 
shall not apply if the Proposed Buyer is an Affiliate of any Stockholder 
which comprises a part of the Come-Along Stockholders.

         4.2 NOTICE. A "Come-Along Notice" shall be delivered by a Stockholder
which is a part of the Come-Along Stockholders on behalf of all such
Stockholders to the Participating Sellers. The Come-Along Notice shall set forth
the principal terms of the proposed purchase (the "Come-Along Transaction")
insofar as it relates to the shares of Stock and other securities of the
Company, the purchase price, the name and address of the Proposed Buyer and the
other principal terms of the proposed Come-Along Transaction. The price for such
Participating Sellers' shares of Stock and other securities of the Company shall
be equal to the per share price applicable to the Come-Along Transaction,
PROVIDED, HOWEVER, that any Stockholder may demand that the proceeds from the
Come-Along Transaction be reallocated among the Stockholders such that the
Stockholders shall be entitled to receive such portion of the proceeds as if the
proceeds were distributed pursuant to Section C.2.a. of Article IV of the
Certificate and PROVIDED FURTHER that such Stockholders who tender securities
which represent the right to purchase shares shall be entitled to receive as
consideration therefor the value of such shares (determined on the basis of the
terms and conditions applicable to the Come-Along Transaction taking into
account the reallocation of the purchase price as aforesaid) purchasable on the
exercise thereof less the exercise price, if any, of the applicable security.

         4.3 CLOSING.

                  (a) If the Come-Along Stockholders consummate the Come-Along
Transaction, the Participating Sellers shall be bound and obligated to sell all
of their shares of Stock and other securities of the Company in the Come-Along
Transaction on the same terms and conditions as the Come-Along Stockholders sell
their shares of Stock and other securities of the Company (including, without
limitation, an agreement to be liable, on a pro rata basis in accordance with
the proceeds received, in respect of any representations, warranties and
indemnities reasonably given in the Come-Along Transaction by the Come-Along
Stockholders). The Stockholders agree that they will also take such actions and
execute such documents and instruments as shall be necessary or desirable in
order to consummate the Come-Along Transaction expeditiously. If at the end of
the one hundred eightieth (180th) day following the date of the Come-Along
Notice the Come-Along Transaction has not been completed, the Come-Along
Stockholders shall be released from their obligations under the Come-Along
Notice, the Come-Along Notice shall be null and void, and it shall be necessary
for a separate Come-Along Notice to have been furnished and the terms and
provisions of this Article 4 separately complied with, in order to consummate a
Come-Along Transaction pursuant to this Article 4. All costs and expenses
incurred by the Come-Along Stockholders in connection with any proposed
Come-Along Transaction as to which a Come-Along Notice shall have been properly
given (whether or not consummated), including without limitation all attorneys'
fees and disbursements, all accounting fees and disbursements and all finders'
or brokerage fees or commissions, shall be paid by the Company.

                  (b) Notwithstanding any other provision of this Agreement, in
the event the consideration to be paid in exchange for shares of Stock and other
securities of the Company in 


                                      9.


<PAGE>

the proposed Come-Along Transaction includes any securities and the receipt 
thereof by a Participating Seller would require under applicable law (i) the 
registration or qualification of such securities or of any person as a broker 
or dealer or agent with respect to such securities or (ii) the provision to 
any participant in the Come-Along Transaction of any information other than 
such information as would be required under Regulation D promulgated under 
the Securities Act in an offering made pursuant to said Regulation D solely 
to "accredited investors" as defined in said Regulation D, the Stockholders 
comprising the Come-Along Stockholders shall have no obligation to cause such 
Participating Seller to receive as to each share and other securities of the 
Company the same amount and kind of securities as the Come-Along Stockholders 
to the extent of such receipt of securities, unless the Come-Along 
Stockholders shall have elected to cause such requirements to have been 
complied with to the extent necessary to permit such Participating Seller to 
receive such securities. The Participating Seller shall be entitled to 
receive, in lieu thereof, against surrender of the shares and other 
securities of the Company (in accordance with the last paragraph of this 
Section 4.3 which would have otherwise been transferred by such Participating 
Seller to the Proposed Buyer in the Come-Along Transaction, an amount in cash 
equal to the fair market value of the securities which such Participating 
Seller would otherwise have received (as determined in good faith by the 
Board of Directors in its sole discretion). In the event such requirements 
have been complied with to the extent necessary to permit such Participating 
Seller to receive such securities, the Participating Seller shall execute 
such documents and instruments, and take such other actions (including 
without limitation, if required by the Come-Along Stockholders, agreeing to 
be represented, without cost to the Participating Seller, during the course 
of such Come-Along Transaction by a "purchaser representative" (as defined in 
Regulation D) in connection with evaluating the merits and risks of the 
prospective investment and acknowledging that he was so represented), as the 
Proposed Buyer or the Company shall reasonably request in order to permit 
such requirements to have been complied with; PROVIDED, HOWEVER, that such 
actions shall not include any expenditure of funds by the Participating 
Seller, it being understood that payment by the Participating Seller of the 
fees and disbursements of any counsel the Participating Seller may elect to 
retain shall be deemed not to constitute a required expenditure of funds for 
purposes of this provision.

                  (c) At the closing of any Come-Along Transaction under this
Article 4, the Participating Sellers shall deliver the shares of Stock and other
securities of the Company to be sold by them, duly endorsed for transfer with
signature guaranteed, free and clear of any liens, against delivery of the
applicable purchase price.

         4.4 STOCK OPTIONS. The parties agree that in connection with the
Company's issuance of stock options pursuant to its 1997 Stock Option Plan the
Company shall impose, to the extent permissible by law, obligations similar to
the provisions in Sections 4.1, 4.2 and 4.3 on the holders of such stock
options.

                                    ARTICLE 5

                                EVENTS OF DEFAULT

         5.1 EVENTS OF DEFAULT. The following events shall be Events of Default
under this Agreement:


                                     10.


<PAGE>

                  (a) The Company shall fail to perform or comply in any
material respect with any of its covenants and agreements in this Agreement, or
under the Certificate or By-Laws and the failure has not been cured within the
Cure Period (a "Company Default").

                  (b) Any Stockholder shall fail to perform or comply in any
material respect with any of its covenants and agreements in this Agreement, and
the failure has not been cured within the Cure Period (a "Stockholder Default").

         5.2 REMEDIES ON DEFAULT. Upon the occurrence of a Company Default or a
Stockholder Default, notice of default shall promptly be given to the defaulting
party. The defaulting party shall have a period of thirty (30) days from the
date of receipt of such notice (the "Cure Period") in which to cure such
default, which it shall in good faith attempt to do. If the Event of Default
shall be continuing at the end of the Cure Period, the non-defaulting parties
shall have available to them all remedies that may be available to them in law
or in equity. In addition, if the default is a Company Default or a Stockholder
Default by the Founding Stockholder, then upon request by any Stockholder not in
default, such Stockholders not in default shall be entitled to appoint to the
Board of Directors that number of directors as shall enable directors appointed
by such Stockholders not in default to approve a Significant Action. Each
Stockholder agrees that it will take any action necessary (including but not
limited to the grant of proxies or the voting of shares of Stock) requested of
it to effect the intention of this provision.

         5.3 NOTICE OF DEFAULT. When any Event of Default shall have occurred,
the Company shall give written notice thereof to each Stockholder within 5
business days after the date that is the earlier of (i) the date that the
Company knows of, or (ii) the date that the Company receives written notice of,
such Event of Default. When in the judgment of any Stockholder an Event of
Default has occurred, the Stockholder shall give written notice thereof to the
Company PROVIDED that the failure to give such notice shall not be a waiver of
the rights of the Stockholder.

         5.4 SPECIFIC ENFORCEMENT. The parties hereto agree that a remedy at law
would not be adequate if a Company Default or a Stockholder Default by the
Founding Stockholder shall have occurred and be continuing. Unless such Default
shall have been waived, the Stockholders not in default may proceed to enforce
their rights under this Article 5 by a suit in equity or an action at law,
including without limitation, a suit for specific performance or injunctive
relief. It is agreed that if one or more Stockholder(s) not in default prevail
in such an action, such prevailing Stockholder(s) shall be entitled to receive
from the Company all reasonable fees, costs and expenses incurred by it,
including without limitation, reasonable fees and expenses of counsel.

         5.5 REMEDIES NOT WAIVED. No course of dealing between the Company and
any Stockholder and no delay in exercising any right, power or remedy conferred
hereunder, shall operate as a waiver of such right, power or remedy or otherwise
prejudice the exercise thereof.


                                      11.


<PAGE>

                                   ARTICLE 6

                                   GOVERNANCE

         6.1 COMPOSITION OF THE BOARD.

                  (a) Each Stockholder agrees to take any and all action
necessary (including, without limitation, the voting of all shares of Stock
owned or held by such Stockholder or over which such Stockholder has voting
control, the execution and delivery of proxies and actions in writing, and the
calling or joining in the calling of special stockholder meetings) to cause
eight Stockholder designees to be elected to the Board of Directors as follows:
(i) one member designated by BankInvest ("BI"), (ii) one member designated by
Dansk Kapitalanlaeg Aktieselskab ("DK"), (iii) one member jointly designated by
Lonmodtagernes Dyrtidsfond ("LD") and Kommunernes Pensionsforsikring A/S ("KP"),
(iv) one member designated by ABN AMRO Ventures B.V., (v) one member designated
by the holders of a majority of the Series E Preferred Stock and (vi) three
members designated by the Founding Stockholder (PROVIDED that one of the
Founding Stockholder's designees shall be the Chief Executive Officer of the
Company).

                  (b) The Stockholders acknowledge that pursuant to Article IV,
Section C.3.e of the Certificate, the holders of the Company's Series C
Preferred Stock are entitled to elect one director in addition to the directors
elected pursuant to Section 6.1(a) of this Agreement.

                  (c) Any director who is elected to the Board of Directors
pursuant to a designation under Section 6.1(a) above may be removed from the
Board of Directors during or upon the completion of such director's term by (and
only by) the Stockholder having made the designation. Upon the occurrence of a
vacancy in the Board of Directors occasioned by the resignation, retirement,
death, disability or removal, or the expiration of the term, of a director
designated under Section 6.1(a) above, the Stockholder having designated such
director shall be entitled to designate the successor thereto and the name of
the individual so designated shall be promptly submitted to the Stockholders for
election by the most expeditious means practicable, and the Stockholders agree
to cause the election of such new designee.

                  (d) The Board of Directors shall elect, from among the
directors of the Company, other than directors designated by the Founding
Stockholder, a chairman of the Board of Directors (the "Chairman"). The Chairman
shall chair all meetings of the Board of Directors and have any other duties
assigned to him by the Board of Directors.

                  (e) The parties agree that given the nature of the Major
Institutional Stockholders, to the extent permitted by applicable law, any
directors appointed pursuant to Section 6.1(a)(i), (ii), (iii), (iv) or (v)
above shall not have a duty to offer to the Company business opportunities of
which such director becomes aware and which falls within the scope of the
business conducted by the Stockholder by whom such director was designated.

                  (f) Any director appointed pursuant to Section 6.1(a)(i),
(ii), (iii), (iv) or (v) will be entitled to indemnification to the full extent
provided by the Certificate and the Corporation law.


                                     12.


<PAGE>

         6.2 FREQUENCY, QUORUM AND VOTING. Regular meetings of the Board of
Directors shall take place no less than four (4) times per year, I.E. one
regular meeting in each calendar quarter. Unless otherwise agreed by all
directors, at least two (2) board meetings per year shall be held in Denmark and
at least two (2) board meetings per year shall be held in the United States.

         6.3 NOTICE OF MEETINGS. The Company shall provide all directors and any
Board Observer with not less than thirty (30) days' notice of all regular
meetings of the Board of Directors, and shall provide such directors with a
detailed agenda of the items to be discussed at such meeting (PROVIDED that a
revised agenda and related materials may be provided to such persons less than
30 days before the meeting). Compliance with such notice provision may be waived
in writing by a director. Any waiver shall be applicable only to one meeting of
the Board of Directors.


         6.4 SPECIAL MEETINGS. Special meetings of the Board of Directors may be
called, on not less than eight (8) days' notice by not fewer than two directors,
at least one of whom shall have been appointed pursuant to Sections 6.1(a)(i),
(ii), (iii), (iv) or (v) and at least one of whom shall have been appointed
pursuant to Section 6.1(a)(vi). The Chairman shall use all reasonable efforts to
communicate in advance of any special meeting with directors who are unable to
attend such meeting to elicit their views on actions proposed to be taken at the
special meeting. Compliance with the notice provision in this paragraph may be
waived in writing by a director. Any waiver shall be applicable only to one
meeting of the Board of Directors.

         6.5 COMPOSITION OF COMMITTEES. Every committee of the Board of
Directors shall include at least one director designated pursuant to Sections
6.1(a)(i), (ii), (iii), (iv) or (v).

         6.6 GOVERNANCE OF SUBSIDIARIES. The Stockholders agree that the board
of directors of each subsidiary of the Company shall be appointed to reasonably
reflect the interests of the Stockholders. Any Major Stockholder may require
that the board of directors of any subsidiary of the Company be comprised of a
number of directors equal to the number of directors of the Company. In such
event, the directors of such subsidiary shall be appointed in the manner
provided herein with respect to the designation of the Board of Directors.

         6.7 STOCKHOLDERS' OBLIGATIONS TO TAKE CERTAIN ACTIONS. Each Stockholder
covenants and agrees that to the extent the effectuation of any Significant
Action requires any act of any Stockholder, such Stockholder will take any
action requested of it by the Board of Directors (including the execution of
proxies, consents, documents or certificates) necessary or helpful to effect the
Significant Action that has been approved as provided for herein.

         6.8 LIMITATION ON DIRECTORS' ACTIONS. Without the consent of all of the
directors who have no interest in any transaction proposed between the Company
and a director or a Stockholder, no director who has an interest in any such
transaction and no director who is a designee of a Stockholder who has an
interest in such a transaction, shall vote upon such transaction. For purposes
of this Section 6.8, the term "transaction" shall not include the decision to
employ or to terminate the employment of an individual, except where the
termination is for cause as defined in the relevant employment agreement, if
any.


                                      13.


<PAGE>

                                    ARTICLE 7

                      AFFIRMATIVE COVENANTS OF THE COMPANY

         The Company hereby covenants and agrees with the Institutional
Stockholders as follows:

         7.1 MATERIAL CHANGES AND LITIGATION. The Company shall promptly notify
the Major Institutional Stockholders of any material adverse change in the
business, assets or condition, financial or otherwise, of the Company, of any
defaults by the Company under any material contract(s) to which the Company is a
party, and of any litigation or governmental proceeding or investigation brought
or, to the best of the Company's knowledge, threatened against the Company, the
Founding Stockholder, any officer, director, key employee or principal
stockholder of the Company which, if adversely determined, would materially
adversely affect the Company or its business, prospects, assets or condition,
financial or otherwise.

         7.2 TRANSACTIONS WITH AFFILIATES. The Company shall promptly disclose
to the Institutional Stockholders the existence of any transaction or
arrangement of which the Company has knowledge with or for the benefit of a
Stockholder, officer or director of the Company or any Affiliate or a member of
the immediate family of the foregoing. In addition, the Company shall require
the prompt disclosure to the Company of any arrangement or transaction involving
any such person. The Company shall not knowingly enter into an arrangement or
transaction with any such person except in conformity with Article 8 hereof.

         7.3 BOARD OBSERVER. The Company will permit any Stockholder who owns at
least five hundred thousand (500,000) shares of capital stock in the Company,
taking into account shares of Preferred Stock issuable upon declaration of the
Special Dividend, to appoint one observer to the Board of Directors (a "Board
Observer"). The Board Observer shall be entitled to attend all meetings of the
Board of Directors and to receive such notice and other information with respect
to such meetings as are delivered to the directors of the Company. The Company
shall not be obligated to reimburse the expenses incurred by the Board Observer.

         7.4 CORPORATE EXISTENCE. The Company shall maintain at all times its
existence as a corporation incorporated and in good standing under the laws of
the State of Delaware, and shall file all necessary documentation, tax returns,
reports and related information required to maintain such existence.

         7.5      FINANCIAL STATEMENTS AND OTHER INFORMATION.

                  (a) The Company shall deliver to each Institutional
Stockholder:

                           (i) within 120 days after the end of each fiscal year
of the Company, an audited balance sheet of the Company as at the end of such
year and audited statements of operations and of cash flows of the Company for
such year, certified by a "Big Five" certified public accountant firm selected
by the Company, and prepared in accordance with generally accepted accounting
principles; and

                           (ii) within 45 days after the end of each fiscal
quarter of the Company, an unaudited balance sheet of the Company as at the end
of such quarter, and unaudited 


                                     14.


<PAGE>

statements of operations and of cash flows of the Company for such fiscal 
quarter and for the current fiscal year to the end of such fiscal quarter.

                  (b) The Company shall deliver to each Major Institutional
Stockholder:

                           (i) within 30 days after the end of each month, an
unaudited balance sheet of the Company as at the end of such month and unaudited
statements of income and of cash flows of the Company for such month and for the
current fiscal year to the end of such month, setting forth in comparative form
the Company's projected financial statement for the corresponding periods for
the current fiscal year;

                           (ii) as soon as available, but in any event within 30
days before commencement of each new fiscal year, a three-year rolling business
plan and a budget (including a capital expenditures budget) for the new fiscal
year.

                           (iii) with reasonable promptness, such other notices,
information and data with respect to the Company as the Company delivers to the
holders of its Common Stock, and such other information and data as such Major
Institutional Stockholder may from time to time reasonably request.

                  (c) Financial statements shall be prepared on a consolidated
basis if the Company then has any majority-owned subsidiaries. The financial
statements delivered pursuant to clause (ii) of paragraph (a) and clause (i) of
paragraph (b) shall be accompanied by a certificate of the chief financial
officer of the Company stating that such statements have been prepared in
accordance with generally accepted accounting principles consistently applied
(except as noted) and fairly present the financial condition and results of
operations of the Company at the date thereof and for the periods covered
thereby.

         7.6 INSPECTION OF BOOKS AND RECORDS. The Company shall permit each
Stockholder holding more than five hundred thousand (500,000) shares of capital
stock, taking into account shares of Preferred Stock issuable upon declaration
of the Special Dividend, or any authorized representative thereof, to visit and
inspect the properties of the Company, including corporate and financial
records, and to discuss its business and finances with officers of the Company,
during normal business hours following reasonable notice and as often as may be
reasonably requested, PROVIDED that such Stockholder executes and delivers a
confidentiality agreement in form and substance reasonably satisfactory to the
Company prior to any such visit and inspection.

         7.7 PAYMENT OF TAXES. The Company shall pay all income, franchise, real
property, sales and other taxes, assessments and levies (whether federal, state
or local) promptly when due.

         7.8 INSURANCE. Until February 3, 2002, the Company shall maintain term
life insurance upon the life of Mark R. Brann in the amount of Five Million
United States Dollars (US $5,000,000), with the proceeds payable to the Company.

         7.9 PATENTS AND INTELLECTUAL PROPERTY. The Company shall maintain a
policy governing the development, use, licensing and protection of its patents
and intellectual property.


                                      15.


<PAGE>


         7.10 NONDISCLOSURE AGREEMENTS. The Company shall require all persons
now or hereafter employed by the Company, whether as employees or consultants,
and who have access to confidential and proprietary information of the Company
to enter into nondisclosure and assignment of inventions agreements in such form
as may be approved by the Board of Directors.

         7.11 EXPENSES AND COMPENSATION OF DIRECTORS.

                  (a) The Company shall promptly reimburse in full each director
of the Company for all reasonable out-of-pocket expenses incurred in attending
each meeting of the Board of Directors or any committee thereof, including,
without limitation, reasonable travel and lodging expenses.

                  (b) The Company shall pay to members of the Board of Directors
who are not employees of the Company annual compensation for their services
pursuant to a compensation arrangement approved by the Board of Directors.

         7.12 RESERVATION OF COMMON STOCK. The Company shall reserve and
maintain a sufficient number of shares of Common Stock for issuance pursuant to
its obligations set forth in the Certificate, and/or issuable upon the exercise
of the Warrants.

         7.13 INTERNATIONAL INVESTMENT AND TRADE IN SERVICES SURVEY ACT. The
Company shall use its best efforts to file on a timely basis all reports
required to be filed by it under 22 U.S.C Section 3104, or any similar statute,
relating to a foreign person's direct or indirect investment in the Company.

         7.14 COPENHAGEN LEAD DISCOVERY PROJECT. The Company agrees to use its
best efforts to develop the Copenhagen Project and to fully utilize proceeds of
the Loan Commitment for that purpose.

         7.15 NOTICE OF CERTAIN BREACHES. The Company covenants and agrees that
it will promptly (but in any event within five (5) business days from the
Company becoming aware of such event) notify the Institutional Stockholders of
any event which alone or with the passage of time or the giving of notice would
constitute a breach of any representation or warranty made by the Company or the
Founding Stockholder in the Series E Stock Purchase Agreement.

         7.16 BUDGETS. The Company agrees that at least 30 days prior to the
commencement of each fiscal year it shall submit to its Board of Directors a
budget for the ensuing fiscal year.

         7.17 CONDUCT OF BUSINESS. The Company covenants and agrees with the
Institutional Investors that it shall, and shall require its officers and
employees to, conduct the business of the Company in accordance with the
business plan and budget approved by the Board of Directors, and otherwise in
accordance with applicable law, rules and regulations and with the highest
professional and ethical standards.

         7.18 PRESERVATION OF SHARES. The Company shall at all times when the
Preferred Stock shall be outstanding, reserve and keep available out of its
authorized but unissued Preferred Stock, for the purpose of declaring and
issuing a Special Dividend, such number of its 


                                     16.


<PAGE>

duly authorized shares of Preferred Stock as shall from time to time be 
sufficient to declare and issue the Special Dividend in accordance with the 
Certificate.

                                    ARTICLE 8

                               NEGATIVE COVENANTS

         The Company shall not take any Significant Action without the prior
approval of the Specified Majority of the Board of Directors. Notwithstanding
the foregoing, the prior approval of the Specified Majority of Directors shall
not be required for the Company to pay the expenses incurred by it in connection
with the transactions contemplated by the Series E Stock Purchase Agreement.

                                    ARTICLE 9

                               REGISTRATION RIGHTS

         9.1 REQUIRED REGISTRATIONS.

                  (a) At any time after the earlier of January 15, 2001 or the
Company's Initial Public Offering, an Institutional Stockholder or Stockholders
holding in the aggregate at least 40% of the Registrable Shares may request, in
writing, that the Company effect the registration on Form S-1 or Form S-2 (or
any successor form) of the Registrable Shares owned by such Institutional
Stockholder or Stockholders having an aggregate offering price of at least
$7,500,000 (based on the then current market price or fair value). If the
holders initiating the registration intend to distribute the Registrable Shares
by means of an underwriting, they shall so advise the Company in their request.
In the event such registration is underwritten, the right of other Institutional
Stockholders to participate shall be conditioned on such Stockholders'
participation in such underwriting. Upon receipt of any such request, the
Company shall promptly give written notice of such proposed registration to all
Institutional Stockholders. Such Stockholder shall have the right, by giving
written notice to the Company within 30 days after the Company provides its
notice, to elect to have included in such registration such of their Registrable
Shares as such Institutional Stockholders may request in such notice of
election; PROVIDED that if the underwriter (if any) managing the offering
determines that, because of marketing factors, all of the Registrable Shares
requested to be registered by all Institutional Stockholders may not be included
in the offering, then all Institutional Stockholders who have requested
registration shall participate in the registration pro rata based upon the
number of Registrable Shares which they have requested to be so registered. If
the underwriter has not limited the number of Registrable Shares to be
underwritten, the Company may include securities for its own account (or for the
account of other stockholders) in such registration if the underwriter so agrees
and if the number of Registrable Shares that would otherwise have been included
in such registration and underwriting will not thereby be limited. Thereupon,
the Company shall, as expeditiously as possible, use its best efforts to effect
the registration on Form S-1 or Form S-2 (or any successor form) of all
Registrable Shares which the Company has been requested to so register.


                                     17.

<PAGE>

                  (b) At any time after the Company becomes eligible to file a
Registration Statement on Form S-3 (or any successor form relating to secondary
offerings), an Institutional Stockholder or Stockholders holding in the
aggregate at least 25% of the Registrable Shares may request the Company, in
writing, to effect the registration on Form S-3 (or such successor form), of
Registrable Shares having an aggregate offering price of at least $500,000
(based on the then current public market price). Upon receipt of any such
request, the Company shall promptly give written notice of such proposed
registration to all the Institutional Stockholders. Such stockholders shall have
the right, by giving written notice to the Company within 30 days after the
Company provides its notice, to elect to have included in such registration such
of their Registrable Shares as such Institutional Stockholders may request in
such notice of election; PROVIDED that if the underwriter (if any) managing the
offering determines that, because of marketing factors, all of the Registrable
Shares requested to be registered by all Institutional Stockholders may not be
included in the offering, then all such Stockholders who have requested
registration shall participate in the registration pro rata based upon the
number of Registrable Shares which they have requested to be so registered. If
the underwriter has not limited the number of Registrable Shares to be
underwritten, the Company may include securities for its own account (or for the
account of other stockholders) in such registration if the underwriter so agrees
and if the number of Registrable Shares that would otherwise have been included
in such registration and underwriting will not thereby be limited. Thereupon,
the Company shall, as expeditiously as possible, use its best efforts to effect
the registration on Form S-3 (or such successor form) of all Registrable Shares
which the Company has been requested to so register.

                  (c) The Company shall not be required to effect more than two
registrations pursuant to paragraph (a) above or more than three registrations
pursuant to paragraph (b) above. In addition, the Company shall not be required
to effect any registration (other than on Form S-3 or any successor form
relating to secondary offerings) within six months after the effective date of
any other Registration Statement of the Company.

                  (d) If at the time of any request to register Registrable
Shares pursuant to this Section 9.1, the Company is engaged or has fixed plans
to engage within 30 days of the time of the request in a registered public
offering as to which the Institutional Stockholders may include Registrable
Shares pursuant to Section 9.2 or is engaged in any other activity which, in the
good faith determination of the Board of Directors, would be adversely affected
by the requested registration to the material detriment of the Company, then the
Company may at its option direct that such request be delayed for a period not
in excess of six months from the effective date of such offering or the date of
commencement of such other material activity, as the case may be, such right to
delay a request may not be exercised by the Company more than once in any
two-year period.

         9.2 INCIDENTAL REGISTRATION.

                  (a) Whenever the Company proposes to file a Registration
Statement (other than pursuant to Section 9.1) at any time and from time to
time, it will, prior to such filing, give written notice to all Institutional
Stockholders of its intention to do so and, upon the written request of an
Institutional Stockholder or Stockholders given within 20 days after the Company
provides such notice (which request shall state the intended method of
disposition of such Registrable Shares), the Company shall use its best efforts
to cause all Registrable Shares which 


                                      18.


<PAGE>

the Company has been requested by such Institutional Stockholder or 
Stockholders to register to be registered under the Securities Act to the 
extent necessary to permit their sale or other disposition in accordance with 
the intended methods of distribution specified in the request of such 
Institutional Stockholder or Stockholders; PROVIDED that the Company shall 
have the right to postpone or withdraw any registration effected pursuant to 
this Section 9.2 without obligation to any Stockholder.

                  (b) In connection with any registration under this Section 9.2
involving an underwriting, the Company shall not be required to include any
Registrable Shares in such registration unless the holders thereof accept the
terms of the underwriting as agreed upon between the Company and the
underwriters selected by it (PROVIDED that such terms must be consistent with
this Agreement). If in the opinion of the managing underwriter it is appropriate
because of marketing factors to limit the number of Registrable Shares to be
included in the offering, then the Company shall be required to include in the
registration only that number of Registrable Shares, if any, which the managing
underwriter believes should be included therein; PROVIDED that no persons or
entities other than the Company, the Institutional Stockholders and persons or
entities holding registration rights shall be permitted to include securities in
the offering. If the number of Registrable Shares to be included in the offering
in accordance with the foregoing is less than the total number of shares which
the holders of Registrable Shares have requested to be included, then the
holders of Registrable Shares who have requested registration and other holders
of securities entitled to include them in such registration shall participate in
the registration pro rata based on their total ownership of shares of Common
Stock (giving effect to the conversion into Common Stock of all securities
convertible thereinto).

         9.3 REGISTRATION PROCEDURES. If and whenever the Company is required by
the provisions of this Agreement to use its best efforts to effect the
registration of any of the Registrable Shares under the Securities Act, the
Company shall:

                  (a) promptly file with the Commission a Registration Statement
with respect to such Registrable Shares and use its best efforts to cause that
Registration Statement to become effective;

                  (b) as expeditiously as possible prepare and file with the
Commission any amendments and supplements to the Registration Statement and the
prospectus included in the Registration Statement as may be necessary to keep
the Registration Statement effective, in the case of a firm commitment
underwritten public offering, until each underwriter has completed the
distribution of all securities purchased by it and, in the case of any other
offering, until the earlier of the sale of all Registrable Shares covered
thereby or 120 days after the effective date thereof;

                  (c) as expeditiously as possible furnish to each selling
Institutional Stockholder such reasonable numbers of copies of the prospectus
and the Registration Statement, including a preliminary prospectus, in
conformity with the requirements of the Securities Act, and such other documents
as the selling Institutional Stockholder may reasonably request in order to
facilitate the public sale or other disposition of the Registrable Shares owned
by the selling Institutional Stockholder;


                                     19.


<PAGE>

                  (d) as expeditiously as possible use its best efforts to
register or qualify the Registrable Shares covered by the Registration Statement
under the securities or Blue Sky laws of such states as the selling
Institutional Stockholders shall reasonably request, and do any and all other
acts and things that may be necessary or desirable to enable the selling
Institutional Stockholders to consummate the public sale or other disposition in
such states of the Registrable Shares owned by the selling Institutional
Stockholder; PROVIDED, HOWEVER, that the Company shall not be required in
connection with this paragraph (d) to qualify as a foreign corporation or
execute a general consent to service of process in any jurisdiction; and

                  (e) furnish to each prospective selling Institutional
Stockholder a signed counterpart of (i) an opinion of counsel for the Company
delivered to the underwriters, dated the effective date of the Registration
Statement, and (ii) to selling Institutional Stockholders from the independent
auditors of the Company, a "comfort" letter delivered to the underwriters and
signed by the independent auditors who have certified the Company's financial
statements included in the Registration Statement, covering substantially the
same matter with respect to events subsequent to the date of the financial
statements, as are customarily covered (at the time of such registration) in
opinions of issuer's counsel and in "comfort" letters delivered to the
underwriters in underwritten public offerings of securities.

         If the Company has delivered preliminary or final prospectuses to the
selling Institutional Stockholders and after having done so the prospectus is
amended to comply with the requirements of the Securities Act, the Company shall
promptly notify the selling Institutional Stockholders and, if requested, the
selling Institutional Stockholders shall immediately cease making offers of
Registrable Shares and return all prospectuses to the Company. The Company shall
promptly provide the selling Institutional Stockholders with revised
prospectuses and, following receipt of the revised prospectuses, the selling
Institutional Stockholders shall be free to resume making offers of the
Registrable Shares.

         9.4 ALLOCATION OF EXPENSES. The Company will pay all Registration
Expenses of all registrations under this Agreement; PROVIDED, HOWEVER, that if a
registration under Section 9.1 is withdrawn at the request of the Institutional
Stockholders requesting such registration (other than as a result of information
concerning the business or financial condition of the Company which is made
known to the Institutional Stockholders after the date on which such
registration was requested) and if the requesting Institutional Stockholders
elect, by majority vote of the securities registered for such Institutional
Stockholders, not to have such registration counted as a registration requested
under Section 9.1, the requesting Institutional Stockholders shall pay the
Registration Expenses of such registration pro rata in accordance with the
number of their Registrable Shares included in such registration. For purposes
of this Section 9.4, the term "Registration Expenses" shall mean all expenses
reasonably incurred by the Company in complying with this Agreement, including,
without limitation, all registration and filing fees, exchange listing fees,
printing expenses, fees and expenses of counsel for the Company and the fees and
expenses of one counsel selected by the selling Institutional Stockholders to
represent the selling Institutional Stockholders, state Blue Sky fees and
expenses, and the expense of any special audits incident to or required by any
such registration, but excluding underwriting discounts, selling commissions and
the fees and expenses of selling Institutional Stockholders' own counsel (other
than the counsel selected to represent all selling Institutional Stockholders).


                                     20.


<PAGE>

         9.5 INDEMNIFICATION AND CONTRIBUTION.

                  (a) In the event of any registration of any of the Registrable
Shares under the Securities Act pursuant to this Agreement, the Company will
indemnify and hold harmless the seller of such Registrable Shares, each
underwriter of such Registrable Shares, and each other person, if any, who
controls such seller or underwriter within the meaning of the Securities Act or
the Exchange Act against any losses, claims, damages or liabilities, joint or
several, to which such seller, underwriter or controlling person may become
subject under the Securities Act, the Exchange Act, state securities or Blue Sky
laws or otherwise, insofar as such losses, claims, damages or liabilities (or
actions in respect thereof) arise out of or are based upon any untrue statement
or alleged untrue statement of any material fact contained in any Registration
Statement under which such Registrable Shares were registered under the
Securities Act, any preliminary prospectus or final prospectus contained in the
Registration Statement, or any amendment or supplement to such Registration
Statement or arise out of or are based upon the omission or alleged omission to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading; and the Company will reimburse such seller,
underwriter and each such controlling person for any legal or any other expenses
reasonably incurred by such seller, underwriter or controlling person in
connection with investigating or defending any such loss, claim, damage,
liability or action; PROVIDED, HOWEVER, that the Company will not be liable in
any such case to the extent that any such loss, claim, damage or liability
arises out of or is based upon any untrue statement or omission made in such
Registration Statement, preliminary prospectus or final prospectus, or any such
amendment or supplement, in reliance upon and in conformity with information
furnished to the Company, in writing, by or on behalf of such seller,
underwriter or controlling person specifically for use in the preparation
thereof.

                  (b) In the event of any registration of any of the Registrable
Shares under the Securities Act pursuant to this Agreement, each seller of
Registrable Shares, severally and not jointly, will indemnify and hold harmless
the Company, each of its directors and officers and each underwriter (if any)
and each person, if any, who controls the Company or any such underwriter within
the meaning of the Securities Act or the Exchange Act, against any losses,
claims, damages or liabilities, joint or several, to which the Company, such
directors and officers, underwriter or controlling person may become subject
under the Securities Act, Exchange Act, state securities or Blue Sky laws or
otherwise, insofar as such losses, claims, damages or liabilities (or actions in
respect thereof) arise out of or are based upon any untrue statement or alleged
untrue statement of a material fact contained in any Registration Statement
under which such Registrable Shares were registered under the Securities Act,
any preliminary prospectus or final prospectus contained in the Registration
Statement, or any amendment or supplement to the Registration Statement, or
arise out of or are based upon any omission or alleged omission to state a
material fact required to be stated therein or necessary to make the statement
therein not misleading, if the statement or omission was made in reliance upon
and in conformity with information relating to such seller furnished in writing
to the Company by or on behalf of such seller specifically for use in connection
with the preparation of such Registration Statement, prospectuses, amendment or
supplement; PROVIDED, HOWEVER, that the obligations of such Institutional
Stockholders hereunder shall be limited to an amount equal to the proceeds to
each Institutional Stockholder of Registrable Shares sold in connection with
such registration.


                                     21.


<PAGE>

                  (c) Each party entitled to indemnification under this Section
9.5 (the "Indemnified Party") shall give notice to the party required to provide
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the Indemnifying Party to assume the defense of any such claim or any
litigation resulting therefrom; PROVIDED that counsel for the Indemnifying
Party, who shall conduct the defense of such claim or litigation, shall be
approved by the Indemnified Party (whose approval shall not be unreasonably
withheld); and, PROVIDED FURTHER that the failure of any Indemnified Party to
give notice as provided herein shall not relieve the Indemnifying Party of its
obligations under this Section 9.5. The Indemnified Party may participate in
such defense at such party's expense; PROVIDED, HOWEVER, that the Indemnifying
Party shall pay such expense if representation of such Indemnified Party by the
counsel retained by the Indemnifying Party would be inappropriate due to actual
or potential differing interests between the Indemnified Party and any other
party represented by such counsel in such proceeding. No Indemnifying Party, in
the defense of any such claim or litigation shall, except with the consent of
each Indemnified Party, consent to entry of any judgment or enter into any
settlement which does not include as an unconditional term thereof the giving by
the claimant or plaintiff to each Indemnified Party of a release from all
liability in respect of such claim or litigation, and no Indemnified Party shall
consent to entry of any judgment or settle such claim or litigation without the
prior written consent of each other Indemnified Party.

                  (d) In order to provide for just and equitable contribution to
joint liability under the Securities Act in any case in which either (i) any
holder of Registrable Shares exercising rights under this Agreement, or any
controlling person of any such holder, makes a claim for indemnification
pursuant to this Section 9.5 but it is judicially determined (by the entry of a
final judgment or decree by a court of competent jurisdiction and the expiration
of time to appeal or the denial of the last right of appeal) that such
indemnification may not be enforced in such case notwithstanding the fact that
this Section 9.5 provides for indemnification in such case, or (ii) contribution
under the Securities Act may be required on the part of any such selling
Institutional Stockholder or any such controlling person in circumstances for
which indemnification is provided under this Section 9.5; then each Indemnifying
Party shall contribute to the amount paid or payable by such Indemnified Party
as a result of such losses, claims, liabilities, or expenses (or actions in
respect thereof) in such proportion as is appropriate to reflect the relative
fault of the Indemnifying Party and the Indemnified Party as well as any other
relevant equitable considerations. The relative fault of such Indemnifying Party
and Indemnified Party shall be determined by reference to, among other things,
whether the untrue or alleged untrue statement of a material fact or omission or
alleged omission to state a material fact relates to information supplied by
such Indemnifying Party or Indemnified Party, and the parties' relative
knowledge, access to information and opportunity to correct or prevent such
statement or omission. The parties hereto agree that it would not be just and
equitable if contribution pursuant to this Section 9.5(d) were determined by pro
rata allocation (even if the Holders were treated as one entity for such
purpose) or by any other method of allocation which does not take account of the
equitable considerations referred to in this Section 9.5(d). The amount paid or
payable by an Indemnified Party as result of the losses, claims, damages,
liabilities, or expenses (or actions in respect thereof) referred to above shall
be deemed to include any legal or other fees or expenses reasonably incurred by
such Indemnified Party in connection with investigating or, except as provided
in Section 9.5(c), defending any such action or claim. Notwithstanding the


                                      22.


<PAGE>

provisions of this Section 9.5(d), (A) no such holder will be required to
contribute any amount in excess of the proceeds to it of all Registrable Shares
sold by it pursuant to such Registration Statement, and (B) no person or entity
guilty of fraudulent misrepresentation, within the meaning of Section 11(f) of
the Securities Act, shall be entitled to contribution from any person or entity
who is not guilty of such fraudulent misrepresentations.

         9.6 INDEMNIFICATION WITH RESPECT TO UNDERWRITTEN OFFERING. In the event
that Registrable Shares are sold pursuant to a Registration Statement in an
underwritten offering pursuant to Section 9.1, the Company agrees to enter into
an underwriting agreement containing customary representations and warranties
with respect to the business and operations of an issuer of the securities being
registered and customary covenants and agreement to be performed by such issuer,
including without limitation customary provisions with respect to
indemnification by the Company of the underwriters of such offering.

         9.7 INFORMATION BY HOLDER. Each Institutional Stockholder including
Registrable Shares in any registration shall furnish to the Company such
information regarding such Institutional Stockholder and the distribution
proposed by such Institutional Stockholder as the Company may reasonably request
in writing and as shall be required in connection with any registration,
qualification or compliance referred to in this Agreement.

         9.8 "STAND-OFF" AGREEMENT. Each Institutional Stockholder, if requested
by the Company and the managing underwriter of an offering by the Company of
Common Stock or other securities of the Company pursuant to a Registration
Statement, shall agree not to sell publicly or otherwise transfer or dispose of
any Registrable Shares or other securities of the Company held by such
Institutional Stockholder for a specified period of time (not to exceed 180
days) following the effective date of such Registration Statement; PROVIDED
that:

                  (a) such agreement shall only apply to the first Registration
Statement covering Common Stock of the Company to the public in an underwritten
offering; and

                  (b) all Institutional Stockholders holding not less than the
number of shares of Common Stock held by such Institutional Stockholder
(including shares of Common Stock issuable upon the conversion of shares of
Stock, or other convertible securities, or upon the exercise of options,
warrants or rights) and all officers and directors of the Company enter into
similar agreements.

         9.9 RULE 144 REQUIREMENTS. After the effective date of the first
Registration Statement filed by the Company for an offering of its securities to
the public, the Company agrees to:

                  (a) make and keep public information available in compliance
with the requirements of Rule 144 under the Securities Act;

                  (b) use its best efforts to file with the Commission in a
timely manner all reports and other documents required of the Company under the
Securities Act and the Exchange Act; and


                                      23.


<PAGE>

                  (c) furnish to a holder of Registrable Shares upon request (i)
a written statement by the Company as to its compliance with the reporting
requirements of said Rule 144, and the reporting requirements of the Securities
Act and the Exchange Act, (ii) a copy of the most recent annual or quarterly
report of the Company, and (iii) such other reports and documents of the Company
as such holder may reasonably request to avail itself of any similar rule or
regulation of the Commission allowing it to sell any such securities without
registration.

         9.10 MERGERS, ETC. The Company shall not, directly or indirectly, enter
in any merger, consolidation or reorganization in which the Company shall not be
the surviving corporation unless the proposed surviving corporation shall, prior
to such merger, consolidation or reorganization, agree in writing to assume the
obligations of the Company under this Agreement and for that purpose references
hereunder to "Registrable Shares" shall be deemed to be references to the
securities which the Stockholders would be entitled to receive in exchange for
Registrable Shares under any such merger, consolidation or reorganization;
PROVIDED, HOWEVER, that the provisions of this Section 9.10 shall not apply in
the event of any merger, consolidation or reorganization in which the Company is
not the surviving corporation if all Institutional Stockholders are entitled to
receive in exchange for their Registrable Shares consideration consisting solely
of (i) cash, (ii) securities of the acquiring corporation which may be
immediately sold to the public without registration under the Securities Act, or
(iii) securities of the acquiring corporation which the acquiring corporation
has agreed to register within 90 days of completion of the transaction for
resale to the public pursuant to the Securities Act.

         9.11 TERMINATION OF REGISTRATION RIGHTS. All of the Company's
obligations to register Registrable Shares under this Agreement shall terminate
on the eighth anniversary of this Agreement. In addition, a Stockholder's
registration rights shall expire if (a) the Company has completed its Initial
Public Offering and is subject to the provisions of the Exchange Act, (b) all
Registrable Shares held by and issuable to such Stockholder (and its Affiliates,
partners, former partners, members and former members) may be sold under Rule
144 during any ninety (90) day period, and (c) Registrable Shares held by such
Stockholder equal less than one percent (1%) of the outstanding shares of Common
Stock (on an as-converted basis).

         9.12 TRANSFERS OF RIGHTS. The registration rights of each Institutional
Stockholder hereunder, along with its obligations related thereto, may be
assigned by such Institutional Stockholder, in whole or in part, to any person
or entity to which shares of Stock are transferred by such Institutional
Stockholder, and such transferee shall be deemed an "Institutional Stockholder"
for purposes of this Agreement generally and this Article 9 specifically)
provided that the Institutional Stockholder or the transferee provides written
notice of such assignment to the Company.

         9.13 REGISTRATION RIGHTS TO THIRD PARTIES. The Company shall not
without the written consent of the holders of at least two-thirds of the
Registrable Shares grant to any third party or group of parties rights with
respect to registration of shares of Stock under the Securities Act on terms
more favorable in the aggregate than those provided herein.

         9.14 CONSTRUCTION. For the purposes of this Article 9 only, the term
"Institutional Stockholders" shall be deemed to include Allergan Sales, Inc.
("Allergan Sales"), the successor to Vision Pharmaceuticals L.P., a Texas
limited partnership ("Vision"), and all references to 


                                     24.


<PAGE>

"Registrable Shares" shall be deemed to include all "Registrable Securities" 
as such term is used in the Stock Purchase Agreement dated September 24, 1997 
between the Company and Vision. Allergan Sales represents and warrants that 
it is the sole transferee of the rights, title and interests of Vision in the 
Series C Preferred Stock.

                                   ARTICLE 10

                                   DEFINITIONS

         10.1 "Affiliate" means, with respect to any Person, any Person who
controls, is controlled by, or is under common control with, such Person.
"Affiliate" also means, with respect to ABN AMRO Ventures B.V., any venture
capital fund or other investment entity that is managed or advised by ABN AMRO
Ventures B.V. or any Affiliate thereof.

         10.2 "BankInvest" means BankInvest 7 Biotechnologi and BankInvest 1
Danske Aktier, collectively.

         10.3 "Board of Directors" means the board of directors of the Company.

         10.4 "Board Observer" has the meaning set forth in Section 7.3 of this
Agreement.

         10.5 "By-Laws" means the Company's By-Laws, as amended.

         10.6 "Certificate" means the Company's Certificate of Incorporation, as
amended and restated.

         10.7 "Commission" means the Securities and Exchange Commission, or any
other Federal agency at the time administering the Securities Act.

         10.8 "Common Stock" means the Common Stock, par value $.0001 per share,
of the Company.

         10.9 "Company" means ACADIA Pharmaceuticals Inc., its successors and
assigns.

         10.10 "Competitor" means any Person who conducts any business activity
of the same or similar kind as the Company or business activity in the
biotechnology, genetic engineering or pharmaceutical industries.

         10.11 "Copenhagen Project" means the Company's research and development
project which is more fully described in the Loan Commitment.

         10.12 "Corporation Law" means the General Corporation Law of the State
of Delaware, as amended.

         10.13 "Co-Sale Transaction" means either of the following events: (i)
shares of Stock representing a majority of the voting power of the Company
become beneficially owned by a single Person (including Affiliates of such
Person), or (ii) excluding shares issued in connection 


                                      25.


<PAGE>

with a strategic relationship as set forth in Section 2.7(g), any shares of 
Stock become beneficially owned by a Competitor or an Affiliate of a 
Competitor.

         10.14 "Cure Period" has that meaning set forth in Section 5.2 of this
Agreement.

         10.15 "Event of Default" has that meaning set forth in Section 5.1 of
this Agreement.

         10.16 "Exchange Act" means the Securities Exchange Act of 1934, as
amended, or any similar Federal statute, and the rules and regulations of the
Commission issued under such Act, as they each may, from time to time, be in
effect.

         10.17 "Existing Institutional Stockholder" has that meaning set forth
in the introductory paragraph to this Agreement.

         10.18 "First Institutional Stockholders" means BankInvest, Dansk
Kapitalanlaeg Aktieselskab, Lonmodtagernes Dyrtidsfond and Kommunernes
Pensionsforsikring A/S.

         10.19 "First Stockholders Agreement" has that meaning set forth in
paragraph B of the Recitals.

         10.20 "First Amended Stockholders Agreement" has that meaning set forth
in paragraph C of the Recitals.

         10.21 "Founding Stockholder" means Mark R. Brann and shall not mean any
assignee or transferee of Mark R. Brann.

         10.22 "Initial Public Offering" means the closing of the Company's
first firm commitment underwritten public offering of its Common Stock under the
Securities Act.

         10.23 "Institutional Stockholder" has that meaning set forth in the
introductory paragraph of this Agreement.

         10.24 "Loan Commitment" means the commitment of Vaekstfonden to lend
the Company the sum of DKK 44,573,063.00.

         10.25 "Major Institutional Stockholder" means any Stockholder, other
than the Founding Stockholder, who owns at least 500,000 shares of Preferred
Stock. For purposes of this definition, all shares of Stock held by Affiliates
of a Stockholder will be aggregated to determine the number of shares of Stock
held by a Stockholder.

         10.26 "Major Stockholder" means each Major Institutional Stockholder
and the Founding Stockholder.

         10.27 "New Institutional Stockholder" has that meaning set forth in the
introductory paragraph to this Agreement.

         10.28 "Offered Securities" has that meaning set forth in Section 2.1 of
this Agreement.

         10.29 "Organizational Documents" means the Certificate and By-Laws.


                                     26.


<PAGE>

         10.30 "Partnership" means Investor Associates RT.

         10.31 "Person" means any individual, partnership (general or limited),
corporation, trust, estate, association, or other entity.

         10.32 "Preferred Stock" means the Series A Preferred Stock, Series B
Preferred Stock, Series C Preferred Stock, Series D Preferred Stock, Series E
Preferred Stock and any other series of preferred stock issued subsequent to the
date of this Agreement.

         10.33 "Qualifying IPO" has the meaning set forth in Section 2.7(f).

         10.34 "Registrable Shares" means (i) the shares of Common Stock issued
or issuable upon conversion of any Preferred Stock, (ii) the shares of Common
Stock into which the Preferred Stock (including Preferred Stock issued pursuant
to the Special Dividend) is reclassified, (iii) the shares of Common Stock
issued or issuable upon exercise of the Warrants, (iv) any shares of Common
Stock, and any shares of Common Stock issued or issuable upon the conversion or
exercise of any other securities, acquired by the Institutional Stockholders
pursuant to this Agreement, the Series A Stock Purchase Agreement, the Series B
Stock Purchase Agreement, the Series D Stock Purchase Agreement or the Series E
Stock Purchase Agreement and (v) any other shares of Common Stock issued in
respect of such shares (because of stock splits, stock dividends,
reclassifications, recapitalizations, or similar events); PROVIDED, HOWEVER,
that shares of Common Stock which are Registrable Shares shall cease to be
Registrable Shares (i) upon any sale pursuant to a Registration Statement or
Rule 144 under the Securities Act or (ii) upon any sale in any manner to a
person or entity which, by virtue of Section 9.12 of this Agreement, is not
entitled to the rights provided by this Agreement. Wherever reference is made in
this Agreement to a request or consent of holders of a certain percentage of
Registrable Shares, the determination of such percentage shall include shares of
Common Stock into which shares of Preferred Stock may be reclassified, including
that number of shares of Preferred Stock to which the applicable Stockholder
would be entitled following the declaration and issuance to the Special
Dividend.

         10.35 "Registration Expenses" means the expenses described in Section
9.4.

         10.36 "Registration Statement" means a registration statement filed by
the Company with the Commission for a public offering and sale of Common Stock
(other than a registration statement on Form S-8 or Form S-4, or their
successors, or any other form for a similar limited purpose, or any registration
statement covering only securities proposed to be issued in exchange for
securities or assets of another corporation).

         10.37 "Second Amended Stockholders Agreement" has the meaning set forth
in paragraph D of the Recitals.

         10.38 "Securities Act" means the Securities Act of 1933, as amended, or
any similar Federal statute, and the rules and regulations of the Commission
issued under such Act, as they each may, from time to time, be in effect.

         10.39 "Series A Preferred Stock" means the Series A Preferred Stock,
$0.01 par value per share, of the Company.


                                      27.

<PAGE>

         10.40 "Series B Preferred Stock" means the Series B Preferred Stock,
$0.01 par value per share, of the Company.

         10.41 "Series C Preferred Stock" means the Series C Preferred Stock,
$0.01 par value per share, of the Company.

         10.42 "Series D Preferred Stock" means the Series D Preferred Stock,
$0.01 par value per share, of the Company.

         10.43 "Series E Preferred Stock" means the Series E Preferred Stock,
$0.01 par value per share, of the Company.

         10.44 "Series A Stock Purchase Agreement" means the Series A Stock
Purchase Agreement between the Company, the Founding Stockholder and the First
Institutional Stockholders, dated February 3, 1997.

         10.45 "Series B Stock Purchase Agreement" means the Series B Stock
Purchase Agreement between and among the Company, the Founding Stockholder, the
Partnership and the First Institutional Stockholders, dated August 12, 1997.

         10.46 "Series C Stock Purchase Agreement" means the Stock Purchase
Agreement between the Company and Vision Pharmaceuticals L.P., dated September
24, 1997.

         10.47 "Series D Stock Purchase Agreement" means the Series D Preferred
Stock Purchase Agreement by and among the Company and the purchasers of the
Series D Preferred Stock, dated August 26, 1998.

         10.48 "Series E Stock Purchase Agreement" means the Series E Preferred
Stock Purchase Agreement by and among the Company and the purchasers of Series E
Preferred Stock, dated as of even date herewith.

         10.49 "Significant Actions" means any of the following actions:

                  (a) the authorization or issuance of any equity securities of
the Company, except for issuance of Common Stock in the manner contemplated by
Section 2.7(b), (c) (PROVIDED that such plan or arrangement is approved in
accordance with Section 10.49(e)) or (d);

                  (b) the declaration or payment of any dividend or any other
distribution, as defined in the Certificate, on Common Stock including without
limitation any stock dividend;

                  (c) making (or permitting an Affiliate of the Company to make)
a loan or advance to, or owning (or permitting an Affiliate of the Company to
own) any stock or other securities of, any subsidiary or other corporation,
partnership or other entity unless it is wholly owned by the Company;

                  (d) entering into a transaction with or for the benefit of any
Stockholder, officer or director of the Company or an Affiliate of any of the
foregoing;


                                     28.


<PAGE>

                  (e) the creation of any equity-based incentive compensation
plan or agreement described in Section 2.7(c) (other than the Company's 1997
Stock Option Plan) and the grant of more than 40,000, in the aggregate, options,
shares or rights thereunder;

                  (f) the guaranty, directly or indirectly, of any indebtedness
of another entity (including subsidiaries of the Company);

                  (g) the merger or consolidation of the Company with or into
another entity, the sale, lease or disposal of all or substantially all of the
assets of the Company, or the acquisition of all or substantially all of the
assets of another entity;

                  (h) a change in the fiscal year of the Company;

                  (i) the adoption or amendment of any policy governing the use,
protection, disclosure, enforcement or distribution of the intellectual property
of the Company;

                  (j) entering into, amending or terminating contracts in excess
of two years in length and involving, in the aggregate, expenditures by the
Company in excess of $150,000;

                  (k) commencing or resolving material litigation;

                  (l) creating or dissolving joint ventures, partnerships, or
subsidiaries;

                  (m) amending the Certificate or By-Laws, or changing the size
of the Board of Directors other than as contemplated by Section 6.1(a);

                  (n) resolving to dissolve or wind up the affairs of the
Company;

                  (o) using the proceeds of the investment made by the
Institutional Stockholders other than in accordance with a budget and business
plan approved by the Board of Directors by a Specified Majority;

                  (p) entering into, amending or terminating the employment
arrangement, including but not limited to written contracts of employment, with
any person who is, or is intended to become, an officer or key employee of the
Company with a base salary in excess of $150,000 per year, the grant of any
discretionary bonus or the approval of any bonus formula;

                  (q) approving the pledge of shares of Stock of the Company by
any Stockholder;

                  (r) waiving an affirmative covenant of the Company set forth
in Article 7 hereof;

                  (s) entering into, amending or terminating any material
contracts (including development contracts);

                  (t) the creation of any lien, pledge or other encumbrance on
any of assets of the Company or its subsidiaries other than as incurred in the
ordinary course of business;


                                      29.


<PAGE>

                  (u) the application for or acceptance of any European Union or
other public grants or subsidies including but not limited to grants or
subsidies for research purposes;

                  (v) acquisition, sale or other disposition of any assets
(other than Intellectual Property Rights) other than in the ordinary course of
business;

                  (w) acquisition, sale or other disposition of any Intellectual
Property Rights other than pursuant to licenses from or licenses to third
parties containing terms and conditions in substantial conformance with standard
terms and conditions for such licenses which have been approved by a Specified
Majority;

                  (x) the delegation of the authority of the Board of Directors,
including the authority to approve significant actions to any person or
committee;

                  (y) the purchase by the Company of any of its outstanding
securities;

                  (z) any material change to the basic strategy of the Company
as a biopharmaceutical company engaged in the discovery of lead compounds for
pharmaceutical development and related applications of its proprietary
technology platform that combines genome-based assays with high-throughput
screening and clinically relevant pharmacology;

                  (aa) the appointment or removal of the auditors of the
Company;

                  (bb) a material change in the accounting principles of the
Company;

                  (cc) any action whereby the Company would become a U.S. Real
Property Holding Company;

                  (dd) a sale or acquisition of any share in any corporate body;
or

                  (ee) any registration of the Company's Securities other than
in accordance with Article 9 hereof.

         10.50 "Significant Number of Stockholders" means at least all of the
Major Stockholders but one (1).

         10.51 "Special Dividend" has that meaning set forth in Section 2.1 of
this Agreement.

         10.52 "Specified Majority" means the affirmative vote of two-thirds of
the directors appointed by the Stockholders pursuant to Section 6.1(a), I.E. if
the number of directors appointed pursuant to Section 6.1(a) is eight (8), the
affirmative vote of six (6) directors and if the number of directors appointed
pursuant to Section 6.1(a) is nine (9), the affirmative vote of six (6)
directors.

         10.53 "Stock" means the issued and outstanding shares of Common Stock
and Preferred Stock.


                                     30.


<PAGE>

         10.54 "Subsidiary" means any entity 50% or more of whose securities are
owned by the Company or as to which the Company has the right to elect a
majority of the board of directors.

         10.55 "Third Amended Stockholders Agreement" has the meaning set forth
in paragraph E of the Recitals.

         10.56 "Warrants" means the Warrants held by certain Stockholders and
Allergan Sales , as the successor to Vision Pharmaceuticals L.P., as of the date
hereof.

                                   ARTICLE 11

                               GENERAL PROVISIONS

         11.1 LEGENDS.

                  (a) The following legends shall appear on the back of any
certificate for shares of Stock issued by the Company to the Stockholders:

                  THE SHARES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER
                  THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), AND MAY
                  NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, ASSIGNED,
                  PLEDGED OR HYPOTHECATED UNLESS (A) PURSUANT TO RULE 144 OR
                  RULE 144A UNDER THE ACT OR (B) THERE IS AN EFFECTIVE
                  REGISTRATION STATEMENT UNDER THE ACT COVERING SUCH SHARES OR
                  (C) THE COMPANY RECEIVES AN OPINION OF COUNSEL FOR THE HOLDER
                  OF THESE SHARES SATISFACTORY TO THE COMPANY AND ITS COUNSEL
                  STATING THAT SUCH SALE, TRANSFER, ASSIGNMENT, PLEDGE OR
                  HYPOTHECATION IS EXEMPT FROM THE REGISTRATION AND PROSPECTUS
                  DELIVERY REQUIREMENTS OF THE ACT.

                  THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO THE
                  TERMS OF A STOCKHOLDERS AGREEMENT AMONG THE COMPANY AND
                  CERTAIN OF ITS STOCKHOLDERS. ANY PURCHASER, ASSIGNEE,
                  TRANSFEREE, PLEDGEE OR OTHER SUCCESSOR TO ANY HOLDER HEREOF IS
                  BOUND BY THE TERMS OF SUCH AGREEMENT, A COPY OF WHICH WILL BE
                  MAILED, WITHOUT CHARGE, WITHIN FIVE (5) DAYS AFTER RECEIPT OF
                  A WRITTEN REQUEST THEREFOR DIRECTED TO THE SECRETARY OF THE
                  COMPANY.

                  (b) A legend substantially as set forth below shall appear on
the back of any certificate for shares of Stock issued to any person not a party
to this Agreement:

                  THE COMPANY AND CERTAIN OF ITS STOCKHOLDERS HAVE ENTERED INTO
                  A STOCKHOLDERS AGREEMENT THE TERMS OF WHICH MAY AFFECT THE
                  RIGHTS OF STOCKHOLDERS NOT 


                                     31.


<PAGE>

                  A PARTY THERETO. THE COMPANY WILL MAIL A COPY OF SUCH 
                  STOCKHOLDERS AGREEMENT TO ANY REGISTERED HOLDER OF ANY OF ITS 
                  CAPITAL STOCK, WITHOUT CHARGE, WITHIN FIVE (5) DAYS AFTER A 
                  WRITTEN REQUEST THEREFOR IS RECEIVED BY THE SECRETARY OF THE 
                  COMPANY.

         11.2 AMENDMENT; TERMINATION. Except as otherwise provided specifically
in this Agreement, this Agreement may be amended or terminated only by a writing
which refers to this Agreement and which is executed by parties to this
Agreement holding 90% of the Stock or their permissible successors and assigns.
Notwithstanding the foregoing, (i) Articles 2, 3, 4, 5, 6, 7 and 8 of this
Agreement shall terminate and be of no further force and effect upon the closing
of a Qualifying IPO and (ii) this Agreement may be amended with only the written
consent of the Company to include additional purchasers of Series E Preferred
Stock as "New Institutional Stockholders" and "Stockholders" and parties hereto.

         11.3 EFFECT OF AGREEMENT. This Agreement shall be binding upon and
shall inure to the benefit of the Company and shall be binding upon and inure to
the benefit of the other parties hereto and any person who acquires shares of
Stock from the Company or from a party hereto in accordance with the terms of
this Agreement (including, without limitation, pursuant to the provisions of
Articles 2 and 3 of this Agreement). Except for the issuance by the Company of
shares and options pursuant to the Company's 1997 Stock Option Plan, the Company
shall not issue any certificate for shares of Stock to any person until such
person shall have first executed and delivered a copy of this Agreement. No
party to this Agreement may assign any of its rights or delegate any of its
duties under this Agreement except in connection with a transfer of its shares
of Stock which complies in all respects with the terms of this Agreement and the
Organizational Documents.

         11.4 COMPUTATION OF PERCENTAGES OR PRO RATA SHARE. All calculations or
determinations in this Agreement pertaining to percentage or pro rata interests
of holders of Preferred Stock shall be calculated on the basis of the number of
shares of Common Stock to which the holder of such Preferred Stock would be
entitled immediately prior to a public offering of Common Stock which causes a
reclassification or conversion of such Preferred Stock under Article IV, Section
C.5. of the Certificate at the date relevant for such determination or
calculation.

         11.5 COUNTERPARTS. This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original but all of which shall
constitute the same Agreement.

         11.6 NOTICES. All notices, elections and other communications pursuant
to this Agreement shall be made in writing and sent to (a) the Company at its
principal business address or (b) to any Stockholder at the address as shown on
the books and records of the Company and shall be deemed to be received the
second business day following deposit with an overnight mail or courier service,
the date of receipt of electronic confirmation of receipt of an electronic
facsimile message or one week after being sent by regular or certified mail,
postage prepaid.

         11.7 ENTIRE AGREEMENT. Except as expressly set forth herein or in an
instrument in writing signed by the party to be bound thereby which makes
reference to this Agreement, this 


                                     32.


<PAGE>

Agreement embodies the entire agreement in relation to its subject matter, 
and supersedes all prior agreements and negotiations.

         11.8 GOVERNING LAW. This Agreement shall in all respects be
interpreted, construed and governed by and in accordance with the internal
substantive law of the State of California.

         11.9 SEVERABILITY. Each Section, Article and lesser section of this
Agreement constitutes a separate and distinct undertaking, covenant and/or
provision hereof. In the event that any provision of is Agreement shall finally
be determined to be unlawful, all such provision shall be deemed severed from
this Agreement, but every other provision of this Agreement shall remain in full
force and effect, and in substitution for any such provision held unlawful,
there shall be substituted a provision of similar import reflecting the original
intent of the parties hereto to the extent permissible under law.

         11.10 CONSTRUCTION. The headings of the Articles and Sections of this
Agreement are inserted for convenience only and shall not be deemed to
constitute a part hereof. Unless otherwise specifically indicated, references in
is Agreement to Articles, Sections, paragraphs and clauses refer to the
Articles, Sections, paragraphs and clauses of this Agreement. All personal
pronouns used in this Agreement, whether used in the masculine, feminine or
neuter gender, shall include all other genders, and the singular shall include
the plural and vice versa.

         11.11 ARBITRATION. Any dispute, controversy or difference arising
between the parties out of or in relation to or in connection with this
Agreement or any breach thereof which cannot be settled between the parties
shall be finally settled under the Rules of Conciliation and Arbitration of the
International Chamber of Commerce (the "ICC") by which each party agrees to be
bound. In any arbitration pursuant to this Section the decision shall be
rendered by the three independent arbitrators who shall be appointed by the ICC
whose decision shall be binding. The seat of the arbitration shall be London,
England. The language of the arbitration shall be English.

                      [THIS SPACE INTENTIONALLY LEFT BLANK]


                                     33.



<PAGE>


         IN WITNESS WHEREOF, the parties to this Agreement, by their duly
authorized representatives and officers have executed this Agreement as of the
date and year first above written.

                                 COMPANY:

                                 ACADIA PHARMACEUTICALS INC.

                                 By: /s/ Leonard Borrmann
                                    --------------------------------------------
                                     Name: Leonard Borrmann
                                     Title: CEO


                                 FOUNDING STOCKHOLDER:

                                     /s/ Mark R. Brann
                                    --------------------------------------------
                                     MARK R. BRANN


                                 EXISTING INSTITUTIONAL STOCKHOLDERS:

                                 ABN AMRO VENTURES B.V.

                                 By: /s/ Fred Phillips
                                    --------------------------------------------
                                     Name: Fred Phillips
                                     Title:

                                 By: /s/ Mark Baldassare
                                    --------------------------------------------
                                     Name: Mark Baldassare
                                     Title: Investment Manager


                                 ALLMANNA PENSIONSFONDEN (5:AP)

                                 By: /s/ T. Nicolin
                                    --------------------------------------------
                                     Name: T. Nicolin
                                     Title: CEO




<PAGE>



                                 BANKINVEST 7 BIOTECHNOLOGI

                                 By: /s/ Finn Moefelt
                                    --------------------------------------------
                                     Name: Finn Moefelt
                                     Title: Man. Director


                                 BANKINVEST 1 DANSKE AKTIER

                                 By: /s/ Finn Moefelt
                                    --------------------------------------------
                                     Name: Finn Moefelt
                                     Title: Man. Director


                                 DANSK KAPITALANLAEG AKTIESELSKAB

                                 By: /s/ Arne J. Gillin
                                    --------------------------------------------
                                     Name: Arne J. Gillin
                                     Title: Vice President

                                 By: /s/ Niels K. Agner
                                    --------------------------------------------
                                     Name: Niels K. Agner
                                     Title: President


                                 KOMMUNERNES PENSIONSFORSIKRING A/S

                                 By: /s/ Jens Bisgaard-Flantlen
                                    --------------------------------------------
                                     Name: Jens Bisgaard-Flantlen
                                     Title: Head of Equities


                                 LARS HELLERUNG CHRISTIANSEN

                                 By: /s/ Lars Hellerung Christiansen
                                    --------------------------------------------
                                     Name:
                                     Title:



<PAGE>


                                 LONMODTAGERNES DYRTIDSFOND

                                 By: /s/ Hans Jorgen Madsen
                                    --------------------------------------------
                                     Name: Hans Jorgen Madsen
                                     Title: Head of Department

                                 By: /s/ Anita Klitgaard
                                    --------------------------------------------
                                     Name: Anita Klitgaard
                                     Title: Secretary


                                 SVENSKA HANDELSBANKEN (GOTEBORG)

                                 By: /s/ E e-Britt Jarfelt
                                    --------------------------------------------
                                     Name: E e-Britt Jarfelt
                                     Title: Senior Vice President

                                 By: /s/ Mats Littorin
                                    --------------------------------------------
                                     Name: Mats Littorin
                                     Title: Vice President and General Counsel


                                 SVENSKA HANDELSBANKEN (MALMO)

                                 By: /s/ Jorna Olycampus
                                    --------------------------------------------
                                     Name:
                                     Title:





<PAGE>



                                 NEW INSTITUTIONAL STOCKHOLDERS:


                                 H&Q LIFE SCIENCES INVESTORS

                                 By: /s/ Alan G. Carr
                                    --------------------------------------------
                                     Name: Alan G. Carr
                                     Title: President


                                 H&Q HEALTHCARE INVESTORS

                                 By: /s/ Alan G. Carr
                                    --------------------------------------------
                                     Name: Alan G. Carr
                                     Title: President


                                 THE KAUFMANN FUND

                                 By: /s/ Lawrence Aumard
                                    --------------------------------------------
                                     Name: Lawrence Aumard
                                     Title: Chairman


                                 EATON VANCE WORLDWIDE HEALTH SCIENCES FUND

                                 By: /s/ Samuel D. Isaly
                                    --------------------------------------------
                                     Name: Samuel D. Isaly
                                     Title: Portfolio Manager


                                 FINSBURY WORLDWIDE PHARMACEUTICAL TRUST

                                 By: /s/ Samuel D. Isaly
                                    --------------------------------------------
                                     Name: Samuel D. Isaly
                                     Title: Portfolio Manager





<PAGE>



                                 LIFE SCIENCE NO. 1 INVESTMENT PARTNERSHIP

                                 By: /s/ David J. Drutz
                                    --------------------------------------------
                                     Name: David J. Drutz
                                     Title: Partner


                                 LIFE SCIENCE NO. 2 INVESTMENT PARTNERSHIP

                                 By: /s/ David J. Drutz
                                    --------------------------------------------
                                     Name: David J. Drutz
                                     Title: Partner


                                 LIFE SCIENCE NO. 3 INVESTMENT PARTNERSHIP

                                 By: /s/ David J. Drutz
                                    --------------------------------------------
                                     Name: David J. Drutz
                                     Title: Partner



<PAGE>



                                 FOR PURPOSES OF ARTICLE 9 ONLY:

                                 ALLERGAN SALES, INC.


                                 BY: /s/ George Lasezkay
                                    --------------------------------------------
                                 NAME: George Lasezkay
                                      ------------------------------------------
                                 TITLE: Vice President
                                       -----------------------------------------






<PAGE>

    THIS WARRANT AND THE SHARES OF COMMON STOCK ISSUED UPON ITS EXERCISE ARE
                         SUBJECT TO THE RESTRICTIONS ON
                 TRANSEER SET FORTH IN SECTION 4 OF THIS WARRANT


Warrant No. R2-_                                       Number of Shares: ______
                                                        (subject to adjustment)

Date of Issuance: February 3, 1997

                           RECEPTOR TECHNOLOGIES, INC.

                          COMMON STOCK PURCHASE WARRANT

                          (Void after February 3, 2002;
               subject to earlier termination as described below)

         Receptor Technologies, Inc., a Delaware corporation (the "Company"),
for value received, hereby certifies that ____________________________, or its
registered assigns (the "Registered Holder"), is entitled, subject to the terms
set forth below, to purchase from the Company, at any time or from time to time
on or after the dare of issuance and on or before the Expiration Date (as
defined in Section 1(b) below), ______ shares of Common Stock, $0.0001 par value
per share, of the Company, at a purchase price of $12.00 per share. The shares
purchasable upon exercise of this Warrant shall be newly issued and shall not be
treasury shares. The shares purchasable upon exercise of this Warrant, and the
purchase price per share, each as adjusted from time to time pursuant to the
provisions of this Warrant, are hereinafter referred to as the "Warrant Shares"
and the "Purchase Price," respectively.

         1. EXERCISE.


                  (a) This Warrant may be exercised by the Registered Holder, in
whole or in part, by surrendering this Warrant, with the purchase form appended
hereto as EXHIBIT I duly executed by such Registered Holder or by such
Registered Holders duly authorized attorney, before the Expiration Date, at the
principal office of the Company, or at such other office or agency as the
Company may designate, accompanied by payment in full, in lawful money of the
United States, of the Purchase Price payable in respect of the number of Warrant
Shares purchased upon such exercise.

                  (b) For purposes of this Warrant, the Expiration Date shall
mean not later than 5:00 p.m. (New York, New York time) on the earlier of (i) 60
days following receipt by the Registered Holder of notice by the Company of
achievement of one of the following two milestones: (x) the initiation by the
Company of Phase II clinical studies pursuant to U.S. FDA regulations or EMEA
regulations (under the U.S. FDA Regulations or the EMEA Regulations, initiation
of Phase II is defined as the first entry into a selective group of relevant
patients of a company developed compound), or (y) the receipt by the Company of
$10,000,000 of gross revenue in a four consecutive fiscal quarter period (gross
revenue to mean all revenues of the Company and its subsidiaries, on a
consolidated basis, less interest earnings, grants, subsidies and extraordinary
items), or (ii) five years after the date of issuance.


                                      1.


<PAGE>

                  (c) Each exercise of this Warrant shall be deemed to have been
effected immediately prior to the close of business on the day on which this
Warrant shall have been surrendered the Company as provided in subsection 1(a)
above (the "Exercise Date"). At such time, the person or persons in whose name
or names any certificates for Warrant Shares shall be issuable upon such
exercise as provided in subsection 1(e) below shall be deemed to have become the
holder or holders of record of the Warrant Shares represented by such
certificates.

                  (d) As soon as practicable after the exercise of this Warrant
in full or in part, and in any event within 10 days thereafter, the Company, at
its expense, will cause to be issued in the name of, and delivered to, the
Registered Holder, or as such Holder (upon payment by such Holder of any
applicable transfer taxes) may direct:

                           (i) a certificate or certificates for the number of
full Warrant Shares to which such Registered Holder shall be entitled upon such
exercise plus, in lieu of any fractional shares to which such Registered Holder
would otherwise be entitled, cash in an amount determined pursuant to Section 3
hereof; and

                           (ii) in case such exercise is in part only, a new
warrant or warrants (dated the date hereof) of like tenor, representing in the
aggregate on the face or faces thereof the right to purchase that number of
Warrant Shares equal (without giving effect to any adjustment therein) to the
number of such shares called for on the face of this Warrant minus the number of
such shares purchased by the Registered Holder upon such exercise.

         2. ADJUSTMENTS.

                  (a) GENERAL. The Purchase Price shall be subject to adjustment
from time to time pursuant to the terms of this Section 2.

                  (b) DILUTING ISSUANCES.

                           (i) SPECIAL DEFINITIONS. For purposes of this
subsection 2(b), the following definitions shall apply:

                                    (A) "OPTION" shall mean rights, options or
warrants to subscribe for, purchase or otherwise acquire Common Stock or
Convertible Securities, excluding options described in clause (III) of
subsection 2(b)(i)(D) below.

                                    (B) "ORIGINAL ISSUE DATE" shall mean the
date on which this Warrant was first issued.

                                    (C) "CONVERTIBLE SECURITIES" shall mean any
evidences of indebtedness, shares or other securities directly or indirectly
convertible into or exchangeable for Common Stock.

                                    (D) "ADDITIONAL SHARES OF COMMON STOCK"
shall mean all shares of Common Stock issued (or, pursuant to subsection
2(b)(iii) below, deemed to be issued) by the Company after the Original Issue
Date, other than shares of Common Stock issued or issuable:


                                      2.


<PAGE>

                                             (I) upon conversion of shares of
Convertible Securities outstanding on the Original Issue Date, (including
Options issued on such Date);

                                             (II) by reason of a dividend, stock
split, split-up or other distribution on shares of Common Stock that are
excluded from the definition of Additional Shares of Common Stock by the
foregoing clause (I) or this clause (II);

                                             (III) to employees or directors of,
or consultants to, the Company pursuant to a plan adopted by the Board of
Directors of the Company;

                                             (IV) by reason of the Special
Series A Dividend or the reclassification of the Company's Series A Preferred
Stock, each as provided for in the Company's Certificate of Incorporation, as
amended; or

                                             (V) upon exercise of the Special
Investor Warrants (as defined in the Stock Purchase Agreement dated February 3,
1997 between the Company and certain purchasers of the Company's Series A
Preferred Stock).

                           (ii) NO ADJUSTMENT OF PURCHASE PRICE. No adjustments
to the Purchase Price shall be made unless the consideration per share
(determined pursuant to subsection 2(b)(v)) for an Additional Share of Common
Stock issued or deemed to be issued by the Company is less than the Adjustment
Price (as defined below) in effect on the date of, and immediately prior to, the
issue of such Additional Shares.

                           (iii) ISSUE OF SECURITIES DEEMED ISSUE OF ADDITIONAL
SHARES OF COMMON STOCK. If the Company at any time or from time to time after
the Original Issue Date shall issue any Options or Convertible Securities or
shall fix a record date for the determination of holders of any class of
securities entitled to receive any such Options of Convertible Securities, then
the maximum number of shares of Common Stock (as set forth in the instrument
relating thereto without regard to any provision contained therein for a
subsequent adjustment of such number) issuable upon the exercise of such Options
or, in the case of Convertible Securities and Options therefor, the conversion
or exchange of such Convertible Securities, shall be deemed to be Additional
Shares of Common Stock issued as of the time of such issue or, in case such a
record date shall have been fixed, as of the close of business on such record
date, provided that Additional Shares of Common Stock shall not be deemed to
have been issued unless the consideration per share (determined pursuant to
subsection 2(b)(v) hereof) of such Additional Shares of Common Stock would be
less than the Adjustment Price in effect on the date of and immediately prior to
such issue, or such record date, as the case may be, and provided further that
in any such case in which Additional Shares of Common Stock are deemed to be
issued:

                                    (A) No further adjustment in the Purchase
Price shall be made upon the subsequent issue of Convertible Securities or
shares of Common Stock upon the exercise of such Options or conversion or
exchange of such Convertible Securities;

                                    (B) If such Options or Convertible
Securities by their terms provide, with passage of time or otherwise, for any
increase in the consideration payable to the Company, upon the exercise,
conversion or exchange thereof, the Adjustment Price computed upon the original
issue thereof (or upon the occurrence of a record date with respect thereto),
and 


                                      3.


<PAGE>

any subsequent adjustments based thereon, shall, upon any such increase 
becoming effective, be recomputed to reflect such increase insofar as it 
affects such Options or the rights of conversion or exchange under such 
Convertible Securities;

                                    (C) Upon the expiration or termination of
any unexercised Option, the Purchase Price shall not be readjusted, but the
Additional Shares of Common Stock deemed issued as the result of the original
issue of such Option shall not be deemed issued for the purposes of any
subsequent adjustment of the Purchase Price;

                                    (D) In the event of any change in the number
of shares of Common Stock issuable upon the exercise, conversion or exchange of
any Option or Convertible Security, including, but not limited to, a change
resulting from the anti-dilution provisions thereof, the Adjustment Price then
in effect shall forthwith be readjusted to such Adjustment Price as would have
obtained had the adjustment which was made upon the issuance of such Option or
Convertible Security not exercised or converted prior to such change been made
upon the basis of such change; and

                                    (E) No readjustment pursuant to Clause (B)
or (D) above shall have the effect of increasing the Purchase Price to an amount
which exceeds the lower of (i) the Purchase Price on the original adjustment
date, or (ii) the Purchase Price that would have resulted from any issuances of
Additional Shares of Common Stock between the original adjustment date and such
readjustment date.

                           (iv) ADJUSTMENT OF PURCHASE PRICE UPON ISSUANCE OF
ADDITIONAL SHARES OF COMMON STOCK. In the event the Company shall at any time
after the Original Issue Date issue Additional Shares of Common Stock (including
Additional Shares of Common Stock deemed to be issued pursuant to subsection
2(b)(iii), but excluding shares issued as a dividend or distribution or upon a
stock split or combination as provided in subsection 2(c)), without
consideration or for a consideration per share less than $2.55 per share, as
adjusted from time to time hereunder (the "Adjustment Price"), then and in such
event, the Purchase Price shall be reduced, concurrently with such issue, to a
price (calculated to the nearest cent) determined by multiplying the Adjustment
Price, as adjusted in accordance with this subsection 2(B)(iv) immediately after
such issue, by 4.70588. For example, if the issue results in an Adjustment Price
of $2.40 per share, then the Purchase Price would be reduced from $12.00 per
share to $11.29 per share ($2.40 x 4.70588 = $11.29). For purposes of this
Warrant, the Adjustment Price shall be reduced in connection with any issue
described above in this subsection 2(b)(iv), concurrently with such issue, to a
price (calculated to the nearest cent) determined by multiplying such Adjustment
Price by a fraction, (A) the numerator of which shall be (1) the number of
shares of Common Stock outstanding immediately prior to such issue plus (2) the
number of shares of Common Stock which the aggregate consideration received or
to be received by the Company for the total number of Additional Shares of
Common Stock so issued would purchase at such Adjustment Price; and (B) the
denominator of which shall be the number of shares of Common Stock outstanding
immediately prior to such issue plus the number of such Additional Shares of
Common Stock so issued; PROVIDED THAT, (i) for the purpose of this subsection
2(b)(iv), all shares of Common Stock issuable upon exercise or conversion of
Options or Convertible Securities outstanding immediately prior to such issue
shall be deemed to be outstanding (other than shares excluded from the
definition of "Additional Shares of Common 


                                   4.


<PAGE>

Stock" by virtue of clause (III) of subsection 2(b)(i)(D)), and (ii) the 
number of shares of Common Stock deemed issuable upon conversion of such 
outstanding Options and Convertible Securities shall not give effect to any 
adjustments to the conversion price or conversion rate of such Option or 
Convertible Securities resulting from the issuance of Additional Shares of 
Common Stock that is the subject of this calculation.

         Notwithstanding the foregoing, the applicable Purchase Price shall not
be so reduced at such time if the amount of such reduction would be an amount
less than $.05, but any such amount shall be carried forward and reduction with
respect thereto made at the time of and together with any subsequent reduction
which, together with such amount and any other amount or amounts so carried
forward, shall aggregate $.05 or more.

                           (v) DETERMINATION OF CONSIDERATION. For purposes of
this subsection 2(b), the consideration received by the Company for the issue of
any Additional Shares of Common Stock shall be computed as follows:

                                    (A) CASH AND PROPERTY. Such consideration
shall:

                                             (I) insofar as it consists of cash,
be computed at the aggregate of cash received by the Company, excluding amounts
paid or payable for accrued interest or accrued dividends;

                                             (II) insofar as it consists of
property other than cash, be computed at the fair market value thereof at the
time of such issue, as determined in good faith by the Board of Directors; and

                                             (III) in the event Additional
Shares of Common Stock are issued together with other shares or securities or
other assets of the Company for consideration which covers both, be the
proportion of such consideration so received, computed as provided in clauses
(I) and (II) above, as determined in good faith by the Board of Directors.

                                    (B) OPTIONS AND CONVERTIBLE SECURITIES. The
consideration per share received by the Company for Additional Shares of Common
Stock deemed to have been issued pursuant to subsection 2(b)(iii), relating to
Options and Convertible Securities, shall be determined by dividing

                                             (x) the total amount, if any,
received or receivable by the Company as consideration for the issue of such
Options or Convertible Securities, plus the minimum aggregate amount of
additional consideration (as set forth in the instruments relating thereto,
without regard to any provision contained therein for a subsequent adjustment of
such consideration) payable to the Company upon the exercise of such Options or
the conversion or exchange of such Convertible Securities, or in the case of
Options for Convertible Securities, the exercise of such Options for Convertible
Securities and the conversion or exchange of such Convertible Securities, by

                                             (y) the maximum number of shares of
Common Stock (as set forth in the instruments relating thereto, without regard
to any provision contained therein 


                                     5.


<PAGE>

for a subsequent adjustment of such number) issuable upon the exercise of 
such Options or the conversion or exchange of such Convertible Securities.

                           (vi) MULTIPLE CLOSING DATES. In the event the Company
shall issue on more than one date Additional Shares of Common Stock which are
comprised of shares of the same series or class of Preferred Stock, and such
issuance dates occur within a period of no more than 120 days, then the Purchase
Price shall be adjusted only once on account of such issuances, with such
adjustment to occur upon the final such issuance and to give effect to all such
issuances as if they occurred on the date of the final such issuance.

                  (c) RECAPITALIZATIONS. If outstanding shares of the Company's
Common Stock shall be subdivided into a greater number of shares or a dividend
in Common Stock shall be paid in respect of Common Stock, the Purchase Price in
effect immediately prior to such subdivision or at the record date of such
dividend shall simultaneously with the effectiveness of such subdivision or
immediately after the record date of such dividend be proportionately reduced.
If outstanding shares of Common Stock shall be combined into a smaller number of
shares, the Purchase Price in effect immediately prior to such combination
shall, simultaneously with the effectiveness of such combination, be
proportionately increased.

                  (d) MERGERS, ETC. If, there shall occur any capital
reorganization or reclassification of the Company's Common Stock (other than a
change in par value or a subdivision or combination as provided for in
subsection 2(c) above), or any consolidation or merger of the Company with or
into another corporation, or a transfer of all or substantially all of the
assets of the Company, then, as part of any such reorganization,
reclassification, consolidation, merger or sale, as the case may be, lawful
provision shall be made so that the Registered Holder of this Warrant shall have
the right thereafter to receive upon the exercise hereof the kind and amount of
shares of stock or other securities or property which such Registered Holder
would have been entitled to receive if, immediately prior to any such
reorganization, reclassification, consolidation, merger or sale, as the case may
be, such Registered Holder had held the number of shares of Common Stock which
were then purchasable upon the exercise of this Warrant. In any such case,
appropriate adjustment (as reasonably determined in good faith by the Board of
Directors of the Company) shall be made in the application of the provisions set
forth herein with respect to the rights and interests thereafter of the
Registered Holder of this Warrant, such that the provisions set forth in this
Section 2 (including provisions with respect to adjustment of the Purchase
Price) shall thereafter be applicable, as nearly as is reasonably practicable,
in relation to any shares of stock or other securities or property thereafter
deliverable upon the exercise of this Warrant.

                  (e) ADJUSTMENT IN NUMBER OF WARRANT SHARES. When any
adjustment is required to be made in the Purchase Price, the number of Warrant
Shares purchasable upon the exercise of this Warrant shall be changed to the
number determined by dividing (i) an amount equal to the number of shares
issuable upon the exercise of this Warrant immediately prior to such adjustment,
multiplied by the Purchase Price in effect immediately prior to such adjustment,
by (ii) the Purchase Price in effect immediately after such adjustment.


                                      6.


<PAGE>

                  (f) CERTIFICATE OF ADJUSTMENT. When any adjustment is required
to be made pursuant to this Section 2, the Company shall promptly mail to the
Registered Holder a certificate setting forth the Purchase Price after such
adjustment and setting forth a brief statement of the facts requiring such
adjustment. Such certificate shall also set forth the kind and amount of stock
or other securities or property into which this Warrant shall be exercisable
following such adjustment.

         3. FRACTIONAL SHARES. The Company shall not be required upon the
exercise of this Warrant to issue any fractional shares, but shall make an
adjustment therefor in cash on the basis of the Fair Market Value per share of
Common Stock. The Fair Market Value per share of Common Stock shall be
determined as follows:

                           (i) If the Common Stock is listed on a national
securities exchange, the Nasdaq National Market, the Nasdaq system, or another
nationally recognized exchange or trading system as of the Exercise Date, the
Fair Market Value per share of Common Stock shall be deemed to be the last
reported sale price per share of Common Stock thereon on the Exercise Date; or,
if no such price is reported on such date, such price on the next preceding
business day (provided that if no such price is reported on the next preceding
business day, the Fair Market Value per share of Common Stock shall be
determined pursuant to clause (ii)).

                           (ii) If the Common Stock is not listed on a national
securities exchange, the Nasdaq National Market, the Nasdaq system or another
nationally recognized exchange or trading system as of the Exercise Date, the
Fair Market Value per share of Common Stock shall be deemed to be the amount
most recently determined by the Board of Directors to represent the fair market
value per share of the Common Stock (including without limitation a
determination for purposes of granting Common Stock options or issuing Common
Stock under an employee benefit plan of the Company); and, upon request of the
Registered Holder the Board of Directors (or a representative thereof) shall
promptly notify the Registered Holder of the Fair Market Value per share of
Common Stock. Notwithstanding the foregoing, if the Board of Directors has not
made such a determination within the three-month period prior to the Exercise
Date, then (A) the Fair Market Value per share of Common Stock shall be the
amount next determined by the Board of Directors to represent the fair market
value per share of the Common Stock (including without limitation a
determination for purposes of granting Common Stock options or issuing Common
Stock under an employee benefit plan of the Company), (B) the Board of Directors
shall make such a determination within 15 days of a request by the Registered
Holder that it do so, and (C) the exercise of this Warrant pursuant to this
Section 3 shall be delayed until such determination is made.

         4. REQUIREMENTS FOR TRANSFER.

                  (a) This Warrant and the Warrant Shares shall not be sold or
transferred unless either (i) they first shall have been registered under the
Securities Act of 1933, as amended (the "Act"), or (ii) the Company first shall
have been furnished with an opinion of legal counsel, reasonably satisfactory to
the Company, to the effect that, in connection with such sale or transfer, it is
not necessary to file a registration statement pursuant to the requirements of
Act.


                                      7.


<PAGE>

                  (b) Notwithstanding the foregoing, no registration or opinion
of counsel shall be required for (i) a transfer by a Registered Holder which is
a partnership to a partner of such partnership or a retired partner of such
partnership who retires after the date hereof, or to the estate of any such
partner or retired partner, if the transferee agrees in writing to be subject to
the terms of this Section 4, or (ii) a transfer made in accordance with Rule 144
under the Act.

                  (c) Each certificate representing Warrant Shares shall bear a
legend substantially in the following form:

                           "The securities represented by this certificate have
                           not been registered under the Securities Act of 1933,
                           as amended, and may not be offered, sold or otherwise
                           transferred, pledged or hypothecated unless and until
                           such securities are registered under such Act or an
                           opinion of counsel satisfactory to the Company is
                           obtained to the effect that such registration is not
                           required."

The foregoing legend shall be removed from the certificates representing any
Warrant Shares, at the request of the holder thereof, at such time as they
become eligible for resale pursuant to Rule 144(k) under the Act.

                  (d) The Warrant Shares shall be subject to the terms and
conditions of a Stockholders Agreement described in the following legend. Each
certificate representing Warrant Shares shall bear a legend substantially in the
following form:

                           "The securities represented by this certificate are
                           subject to the terms and conditions of a Stockholders
                           Agreement dated February 3, 1997, among the Company
                           and certain of its stockholders. Any purchaser,
                           assignee, transferee, pledgee or other successor to
                           any holder hereof is bound by the terms of such
                           Agreement, a copy of which will be mailed, without
                           charge, within five (5) days after receipt of a
                           written request therefor directed to the Secretary of
                           the Company.

         5. NO IMPAIRMENT. The Company will not, by amendment of its charter or
through reorganization, consolidation, merger, dissolution, sale of assets or
any other voluntary action avoid or seek to avoid the observance or performance
of any of the terms of this Warrant, but will at all times in good faith assist
in the carrying out of all such terms and in the taking of all such action as
may be necessary or appropriate in order to protect the rights of the holder of
this Warrant against impairment.

         6. LIQUIDATING DIVIDENDS. If the Company pays a dividend or makes a
distribution on the Common Stock payable otherwise than in cash out of earnings
or earned surplus (determined in accordance with generally accepted accounting
principles) except for a stock dividend payable in shares of Common Stock (a
"Liquidating Dividend"), then the Company will pay or distribute to the
Registered Holder of this Warrant, upon the exercise hereof, in addition 


                                      8.


<PAGE>

to the Warrant Shares purchased upon such exercise, the Liquidating Dividend, 
plus interest thereon at the rate per annum then paid by the Company to its 
primary commercial lender, which would have been paid to such Registered 
Holder if he had been the owner of record of such Warrant Shares immediately 
prior to the date on which a record is taken for such Liquidating Dividend 
or, if no record is taken, the date as of which the record holders of Common 
Stock entitled to such dividends or distribution are to be determined.

         7.       NOTICES OF RECORD DATE, ETC.  In case:

                  (a) the Company shall take a record of the holders of its
Common Stock (or other stock or securities at the time deliverable upon the
exercise of this Warrant) for the purpose of entitling or enabling them to
receive any dividend or other distribution, or to receive any right to subscribe
for or purchase any shares of stock of any class or any other securities, or to
receive any other right; or

                  (b) of any capital reorganization of the Company, any
reclassification of the capital stock of the Company, any consolidation or
merger of the Company with or into another corporation (other than a
consolidation or merger in which the Company is the surviving entity), or any
transfer of all or substantially all of the assets of the Company; or

                  (c) of the voluntary or involuntary dissolution, liquidation
or winding-up of the Company,

then, and in each such case, the Company will mail or cause to be mailed to the
Registered Holder of this Warrant a notice specifying, as the case may be, (i)
the date on which a record is to be taken for the purpose of such dividend,
distribution or right, and stating the amount and character of such dividend,
distribution or right, or (ii) the effective date on which such reorganization,
reclassification, consolidation, merger, transfer, dissolution, liquidation or
winding-up is to take place, and the time, if any is to be fixed, as of which
the holders of record of Common Stock (or such other stock or securities at the
time deliverable upon the exercise of this Warrant) shall be entitled to
exchange their shares of Common Stock (or such other stock or securities), for
securities or other property deliverable upon such reorganization,
reclassification, consolidation, merger, transfer, dissolution, liquidation or
winding-up. Such notice shall be mailed at least ten (10) days prior to the
record date or effective date for the event specified in such notice.

         8. RESERVATION OF STOCK. The Company will at all times reserve and keep
available, solely for issuance and delivery upon the exercise of this Warrant,
such number of Warrant Shares and other stock, securities and property, as from
time to time shall be issuable upon the exercise of this Warrant.

         9. EXCHANGE OF WARRANTS. Upon the surrender by the Registered Holder of
any Warrant or Warrants, properly endorsed, to the Company for exchange at the
principal office of the Company, the Company will, subject to the provisions of
Section 4 hereof, issue and deliver to or upon the order of such Holder, at the
Company's expense, a new Warrant or Warrants of like tenor, in the name of such
Registered Holder or as such Registered Holder (upon payment by such Registered
Holder of any applicable transfer taxes) may direct, calling in the aggregate


                                      9.


<PAGE>

the face or faces thereof for the number of shares of Common Stock called for on
the face or faces of the Warrant or Warrants so surrendered.

         10. REPLACEMENT OF WARRANTS. Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and (in the case of loss, theft or destruction) upon delivery of an
indemnity agreement (with surety if reasonably required) in an amount reasonably
satisfactory to the Company, or (in the case of mutilation) upon surrender and
cancellation of this Warrant, the Company will issue, in lieu thereof, a new
Warrant of like tenor.

         11. TRANSFERS, ETC.

                  (a) The Company will maintain a register containing the names
and addresses of the Registered Holders of this Warrant. Any Registered Holder
may change its or his address as shown on the warrant register by written notice
to the Company requesting such change.

                  (b) Subject to the provisions of Section 4 hereof, this
Warrant and all rights hereunder are transferable, in whole or in part, upon
surrender of this Warrant with a properly executed assignment (in the form of
EXHIBIT II hereto) at the principal office of the Company.

                  (c) Until any transfer of this Warrant is made in the warrant
register, the Company may treat the Registered Holder of this Warrant as the
absolute owner hereof for all purposes; PROVIDED, HOWEVER, that if and when this
Warrant is properly assigned in blank, the Company may (but shall not be
obligated to) treat the bearer hereof as the absolute owner hereof for all
purposes, notwithstanding any notice to the contrary.

         12. MAILING OF NOTICES, ETC. All notices and other communications from
the Company to the Registered Holder of this Warrant shall be mailed by
first-class certified or registered mail, postage prepaid, to the address
furnished to the Company in writing by the last Registered Holder of this
Warrant who shall have furnished an address to the Company in writing. All
notices and other communications from the Registered Holder of this Warrant or
in connection herewith to the Company shall be mailed by first-class certified
or registered mail, postage prepaid, to the Company at its principal office set
forth below. If the Company should at any time change the location of its
principal office to a place other than as set forth below, it shall give prompt
written notice to the Registered Holder of this Warrant and thereafter all
references in this Warrant to the location of its principal office at the
particular time shall be as so specified in such notice.

         13. NO RIGHTS AS STOCKHOLDER. Until the exercise of this Warrant, the
Registered Holder of this Warrant shall not have or exercise any rights by
virtue hereof as a stockholder of the Company.

         14. CHANGE OR WAIVER. This Warrant is one of a series of Warrants
issued by the Company (Series R1 and R2), all dated the date hereof and of like
or similar tenor (collectively, the "Company Warrants"). Any term of this
Warrant may only be amended or waived upon the written consent of the Company
and the Registered Holder of this Warrant.


                                      10.


<PAGE>

         15. HEADINGS. The headings in this Warrant are for purposes of
reference only and shall not limit or otherwise affect the meaning of any
provision of this Warrant.

         16. GOVERNING LAW. This Warrant will be governed by and construed in
accordance with the laws of the State of Delaware.

         17. ARBITRATION. Any dispute, controversy or difference arising between
the parties out of or in relation to or in connection with this Agreement or any
breach thereof which cannot be settled between the parties shall be finally
settled under the Rules of Conciliation and Arbitration of the International
Chamber of Commerce (the "ICC") by which each party agrees to be bound. In any
arbitration pursuant to this Section the decision shall be rendered by three
independent arbitrators who shall be appointed by the ICC, whose decision shall
be binding. The seat of arbitration shall be London, England. The language of
arbitration shall be English.

                                              Receptor Technologies, Inc.


                                              By: 
                                                 -------------------------------
                                                  Mark R. Brann, President

[Corporate Seal]

ATTEST: 


-----------------------------------



                                     11.



<PAGE>

                                                                       EXHIBIT I

                                  PURCHASE FORM


To:______________________                                Dated:_________________


         The undersigned, pursuant to the provisions set forth in the attached
Warrant (No. ___), hereby irrevocably elects to purchase ______ shares of the
Common Stock covered by such Warrant. The undersigned herewith makes payment of
$____________ (in lawful money of the United States), representing the full
purchase price for such shares at the price per share provided for in such
Warrant.

                                        Signature:                              
                                                  ------------------------------

                                        Address:                                
                                                --------------------------------

                                        ----------------------------------------




<PAGE>



                                                                     EXHIBIT II

                                 ASSIGNMENT FORM


         FOR VALUE RECEIVED, _____________________________ hereby sells, assigns
and transfers all of the rights of the undersigned under the attached Warrant
(No. __) with respect to the number of shares of Common Stock covered thereby
set forth below, unto:

NAME OF ASSIGNEE            ADDRESS                               NO. OF SHARES
______________________      ________________________________      _____________


Dated:                                    Signature:                            
      ----------------------------                  ----------------------------

Dated:                                    Witness:                              
      ----------------------------                ------------------------------





<PAGE>

                               INDEMNITY AGREEMENT


         THIS AGREEMENT is made and entered into this _______ day of __________,
2001 by and between ACADIA Pharmaceuticals Inc., a Delaware corporation (the
"Corporation"), and _______________ ("Agent").

                                    RECITALS

         WHEREAS, Agent performs a valuable service to the Corporation in
_____________ capacity as ______________ of the Corporation;

         WHEREAS, the stockholders of the Corporation have adopted bylaws (the
"Bylaws") providing for the indemnification of the directors, officers,
employees and other agents of the Corporation, including persons serving at the
request of the Corporation in such capacities with other corporations or
enterprises, as authorized by the Delaware General Corporation Law, as amended
(the "Code");

         WHEREAS, the Bylaws and the Code, by their non-exclusive nature, permit
contracts between the Corporation and its agents, officers, employees and other
agents with respect to indemnification of such persons; and

         WHEREAS, in order to induce Agent to continue to serve as
______________ of the Corporation, the Corporation has determined and agreed to
enter into this Agreement with Agent;

         NOW, THEREFORE, in consideration of Agent's continued service as
______________ after the date hereof, the parties hereto agree as follows:

                                    AGREEMENT

         1. SERVICES TO THE CORPORATION. Agent will
 serve, at the will of the
Corporation or under separate contract, if any such contract exists, as
______________ of the Corporation or as a director, officer or other fiduciary
of an affiliate of the Corporation (including any employee benefit plan of the
Corporation) faithfully and to the best of ______________ ability so long as he
is duly elected and qualified in accordance with the provisions of the Bylaws or
other applicable charter documents of the Corporation or such affiliate;
PROVIDED, HOWEVER, that Agent may at any time and for any reason resign from
such position (subject to any contractual obligation that Agent may have assumed
apart from this Agreement) and that the Corporation or any affiliate shall have
no obligation under this Agreement to continue Agent in any such position.

         2. INDEMNITY OF AGENT. The Corporation hereby agrees to hold harmless
and indemnify Agent to the fullest extent authorized or permitted by the
provisions of the Bylaws and the Code, as the same may be amended from time to
time (but, only to the extent that such amendment permits the Corporation to
provide broader indemnification rights than the Bylaws or the Code permitted
prior to adoption of such amendment).


                                      1.


<PAGE>

         3. ADDITIONAL INDEMNITY. In addition to and not in limitation of the
indemnification otherwise provided for herein, and subject only to the
exclusions set forth in Section 4 hereof, the Corporation hereby further agrees
to hold harmless and indemnify Agent:

                  (a) against any and all expenses (including attorneys' fees),
witness fees, damages, judgments, fines and amounts paid in settlement and any
other amounts that Agent becomes legally obligated to pay because of any claim
or claims made against or by him in connection with any threatened, pending or
completed action, suit or proceeding, whether civil, criminal, arbitrational,
administrative or investigative (including an action by or in the right of the
Corporation) to which Agent is, was or at any time becomes a party, or is
threatened to be made a party, by reason of the fact that Agent is, was or at
any time becomes a director, officer, employee or other agent of Corporation, or
is or was serving or at any time serves at the request of the Corporation as a
director, officer, employee or other agent of another corporation, partnership,
joint venture, trust, employee benefit plan or other enterprise; and

                  (b) otherwise to the fullest extent as may be provided to
Agent by the Corporation under the non-exclusivity provisions of the Code and
Section 41 of the Bylaws.

         4. LIMITATIONS ON ADDITIONAL INDEMNITY. No indemnity pursuant to
Section 3 hereof shall be paid by the Corporation:

                  (a) on account of any claim against Agent solely for an
accounting of profits made from the purchase or sale by Agent of securities of
the Corporation pursuant to the provisions of Section 16(b) of the Securities
Exchange Act of 1934 and amendments thereto or similar provisions of any
federal, state or local statutory law;

                  (b) on account of Agent's conduct that is established by a
final judgment as knowingly fraudulent or deliberately dishonest or that
constituted willful misconduct;

                  (c) on account of Agent's conduct that is established by a
final judgment as constituting a breach of Agent's duty of loyalty to the
Corporation or resulting in any personal profit or advantage to which Agent was
not legally entitled;

                  (d) for which payment is actually made to Agent under a valid
and collectible insurance policy or under a valid and enforceable indemnity
clause, bylaw or agreement, except in respect of any excess beyond payment under
such insurance, clause, bylaw or agreement;

                  (e) if indemnification is not lawful (and, in this respect,
both the Corporation and Agent have been advised that the Securities and
Exchange Commission believes that indemnification for liabilities arising under
the federal securities laws is against public policy and is, therefore,
unenforceable and that claims for indemnification should be submitted to
appropriate courts for adjudication); or

                  (f) in connection with any proceeding (or part thereof)
initiated by Agent, or any proceeding by Agent against the Corporation or its
directors, officers, employees or other agents, unless (i) such indemnification
is expressly required to be made by law, (ii) the proceeding was authorized by
the Board of Directors of the Corporation, (iii) such indemnification is
provided by the Corporation, in its sole discretion, pursuant to the powers


                                     2.


<PAGE>


vested in the Corporation under the Code, or (iv) the proceeding is initiated
pursuant to Section 9 hereof.

         5. CONTINUATION OF INDEMNITY. All agreements and obligations of the
Corporation contained herein shall continue during the period Agent is a
director, officer, employee or other agent of the Corporation (or is or was
serving at the request of the Corporation as a director, officer, employee or
other agent of another corporation, partnership, joint venture, trust, employee
benefit plan or other enterprise) and shall continue thereafter so long as Agent
shall be subject to any possible claim or threatened, pending or completed
action, suit or proceeding, whether civil, criminal, arbitrational,
administrative or investigative, by reason of the fact that Agent was serving in
the capacity referred to herein.

         6. PARTIAL INDEMNIFICATION. Agent shall be entitled under this
Agreement to indemnification by the Corporation for a portion of the expenses
(including attorneys' fees), witness fees, damages, judgments, fines and amounts
paid in settlement and any other amounts that Agent becomes legally obligated to
pay in connection with any action, suit or proceeding referred to in Section 3
hereof even if not entitled hereunder to indemnification for the total amount
thereof, and the Corporation shall indemnify Agent for the portion thereof to
which Agent is entitled.

         7. NOTIFICATION AND DEFENSE OF CLAIM. Not later than thirty (30) days
after receipt by Agent of notice of the commencement of any action, suit or
proceeding, Agent will, if a claim in respect thereof is to be made against the
Corporation under this Agreement, notify the Corporation of the commencement
thereof; but the omission so to notify the Corporation will not relieve it from
any liability which it may have to Agent otherwise than under this Agreement.
With respect to any such action, suit or proceeding as to which Agent notifies
the Corporation of the commencement thereof:

                  (a) the Corporation will be entitled to participate therein at
its own expense;

                  (b) except as otherwise provided below, the Corporation may,
at its option and jointly with any other indemnifying party similarly notified
and electing to assume such defense, assume the defense thereof, with counsel
reasonably satisfactory to Agent. After notice from the Corporation to Agent of
its election to assume the defense thereof, the Corporation will not be liable
to Agent under this Agreement for any legal or other expenses subsequently
incurred by Agent in connection with the defense thereof except for reasonable
costs of investigation or otherwise as provided below. Agent shall have the
right to employ separate counsel in such action, suit or proceeding but the fees
and expenses of such counsel incurred after notice from the Corporation of its
assumption of the defense thereof shall be at the expense of Agent unless (i)
the employment of counsel by Agent has been authorized by the Corporation, (ii)
Agent shall have reasonably concluded, and so notified the Corporation, that
there is an actual conflict of interest between the Corporation and Agent in the
conduct of the defense of such action or (iii) the Corporation shall not in fact
have employed counsel to assume the defense of such action, in each of which
cases the fees and expenses of Agent's separate counsel shall be at the expense
of the Corporation. The Corporation shall not be entitled to assume the defense
of any action, suit or proceeding brought by or on behalf of the Corporation or
as to which Agent shall have made the conclusion provided for in clause (ii)
above; and


                                      3.


<PAGE>

                  (c) the Corporation shall not be liable to indemnify Agent
under this Agreement for any amounts paid in settlement of any action or claim
effected without its written consent, which shall not be unreasonably withheld.
The Corporation shall be permitted to settle any action except that it shall not
settle any action or claim in any manner which would impose any penalty or
limitation on Agent without Agent's written consent, which may be given or
withheld in Agent's sole discretion.

         8. EXPENSES. The Corporation shall advance, prior to the final
disposition of any proceeding, promptly following request therefor, all expenses
incurred by Agent in connection with such proceeding upon receipt of an
undertaking by or on behalf of Agent to repay said amounts if it shall be
determined ultimately that Agent is not entitled to be indemnified under the
provisions of this Agreement, the Bylaws, the Code or otherwise.

         9. ENFORCEMENT. Any right to indemnification or advances granted by
this Agreement to Agent shall be enforceable by or on behalf of Agent in any
court of competent jurisdiction if (i) the claim for indemnification or advances
is denied, in whole or in part, or (ii) no disposition of such claim is made
within ninety (90) days of request therefor. Agent, in such enforcement action,
if successful in whole or in part, shall be entitled to be paid also the expense
of prosecuting ______________ claim. It shall be a defense to any action for
which a claim for indemnification is made under Section 3 hereof (other than an
action brought to enforce a claim for expenses pursuant to Section 8 hereof,
PROVIDED THAT the required undertaking has been tendered to the Corporation)
that Agent is not entitled to indemnification because of the limitations set
forth in Section 4 hereof. Neither the failure of the Corporation (including its
Board of Directors or its stockholders) to have made a determination prior to
the commencement of such enforcement action that indemnification of Agent is
proper in the circumstances, nor an actual determination by the Corporation
(including its Board of Directors or its stockholders) that such indemnification
is improper shall be a defense to the action or create a presumption that Agent
is not entitled to indemnification under this Agreement or otherwise.

         10. SUBROGATION. In the event of payment under this Agreement, the
Corporation shall be subrogated to the extent of such payment to all of the
rights of recovery of Agent, who shall execute all documents required and shall
do all acts that may be necessary to secure such rights and to enable the
Corporation effectively to bring suit to enforce such rights.

         11. NON-EXCLUSIVITY OF RIGHTS. The rights conferred on Agent by this
Agreement shall not be exclusive of any other right which Agent may have or
hereafter acquire under any statute, provision of the Corporation's Certificate
of Incorporation or Bylaws, agreement, vote of stockholders or directors, or
otherwise, both as to action in ______________ official capacity and as to
action in another capacity while holding office.

         12. SURVIVAL OF RIGHTS.

                  (a) The rights conferred on Agent by this Agreement shall
continue after Agent has ceased to be a director, officer, employee or other
agent of the Corporation or to serve at the request of the Corporation as a
director, officer, employee or other agent of another corporation, partnership,
joint venture, trust, employee benefit plan or other enterprise and shall inure
to the benefit of Agent's heirs, executors and administrators.


                                     4.


<PAGE>

                  (b) The Corporation shall require any successor (whether
direct or indirect, by purchase, merger, consolidation or otherwise) to all or
substantially all of the business or assets of the Corporation, expressly to
assume and agree to perform this Agreement in the same manner and to the same
extent that the Corporation would be required to perform if no such succession
had taken place.

         13. SEPARABILITY. Each of the provisions of this Agreement is a
separate and distinct agreement and independent of the others, so that if any
provision hereof shall be held to be invalid for any reason, such invalidity or
unenforceability shall not affect the validity or enforceability of the other
provisions hereof. Furthermore, if this Agreement shall be invalidated in its
entirety on any ground, then the Corporation shall nevertheless indemnify Agent
to the fullest extent provided by the Bylaws, the Code or any other applicable
law.

         14. GOVERNING LAW. This Agreement shall be interpreted and enforced in
accordance with the laws of the State of Delaware.

         15. AMENDMENT AND TERMINATION. No amendment, modification, termination
or cancellation of this Agreement shall be effective unless in writing signed by
both parties hereto.

         16. IDENTICAL COUNTERPARTS. This Agreement may be executed in one or
more counterparts, each of which shall for all purposes be deemed to be an
original but all of which together shall constitute but one and the same
Agreement. Only one such counterpart need be produced to evidence the existence
of this Agreement.

         17. HEADINGS. The headings of the sections of this Agreement are
inserted for convenience only and shall not be deemed to constitute part of this
Agreement or to affect the construction hereof.

         18. NOTICES. All notices, requests, demands and other communications
hereunder shall be in writing and shall be deemed to have been duly given (i)
upon delivery if delivered by hand to the party to whom such communication was
directed or (ii) upon the third business day after the date on which such
communication was mailed if mailed by certified or registered mail with postage
prepaid:

                  (a) If to Agent, at the address indicated on the signature
page hereof.

                  (b) If to the Corporation, to:

                           ACADIA PHARMACEUTICALS INC.
                           3911 Sorrento Valley Boulevard
                           San Diego, California  92121

or to such other address as may have been furnished to Agent by the Corporation.


                                      5.


<PAGE>



         IN WITNESS WHEREOF, the parties hereto have executed this Agreement on
and as of the day and year first above written.

                                     ACADIA PHARMACEUTICALS INC.



                                     By:                                        
                                        ----------------------------------------

                                     Title:                                     
                                           -------------------------------------


                                     AGENT

                                           -------------------------------------


                                     Address:

                                           -------------------------------------

                                           -------------------------------------


                                      6.



<PAGE>

                           ACADIA PHARMACEUTICALS INC.

                             1997 STOCK OPTION PLAN
                             AMENDED BY THE BOARD OF
                   DIRECTORS AND STOCKHOLDERS: APRIL 22, 1999 
               AMENDED BY THE BOARD OF DIRECTORS: NOVEMBER 3, 2000
                            APPROVED BY STOCKHOLDERS:


1.       PURPOSE

         The purpose of this 1997 Stock Option Plan (the "Plan") of ACADIA
Pharmaceuticals Inc., a Delaware corporation (the "Company"), is to advance the
interests of the Company's stockholders by enhancing the Company's ability to
attract, retain and motivate persons who make (or are expected to make)
important contributions to the Company by providing such persons with equity
ownership opportunities and performance-based incentives and thereby better
aligning the interests of such persons with those of the Company's stockholders.
Except where the context otherwise requires, the term "Company" shall include
any present or a future subsidiary corporations of ACADIA Pharmaceuticals Inc.,
as defined in Section 424(f) of the Internal Revenue Code of 1986, as amended,
and any regulations promulgated thereunder (the "Code") (a "Subsidiary").

2.       ELIGIBILITY

         All of the Company's employees, officers, directors, consultants and
advisors are eligible to be granted options ("Options") to purchase the
Company's common stock, $0.0001
 par value per share ("Common Stock"), under the
Plan. Any person who has been granted an Option under the Plan shall be deemed a
"Participant".

3.       ADMINISTRATION, DELEGATION

         (a) ADMINISTRATION BY BOARD OF DIRECTORS. The Plan will be administered
by the Board of Directors of the Company (the "Board"). The Board shall have
authority to grant Options and to adopt, amend and repeal such administrative
rules, guidelines and practices relating to the Plan as it shall deem advisable
from time to time, to interpret and correct the provisions of the Plan and any
Option. No member of the Board shall be liable for any action or determination
relating to the Plan. All decisions by the Board shall be made in their sole
discretion and shall be final and binding on all persons having or claiming any
interest in the Plan or in any Option.

         (b) DELEGATION TO EXECUTIVE OFFICERS. To the extent permitted by
applicable law, the Board may delegate to one or more executive officers of the
Company the power to grant Options and exercise such other powers under the Plan
as the Board may determine, provided that the Board shall fix the maximum number
of shares subject to Options and the maximum number of shares for any one
Participant to be made by such executive officers.


                                      1.


<PAGE>

         APPOINTMENT OF COMMITTEES. To the extent permitted by applicable law,
the Board may delegate any or all of its powers under the Plan to one or more
committees or subcommittees of the Board (a "Committee"). If and when the Common
Stock is registered under the Securities Exchange Act of 1934 (the "Exchange
Act"), the Board shall appoint one such Committee of not less than two members,
each member of which shall be an "outside director" within the meaning of
Section 162(m) of the Code and a "non-employee director" as defined in Rule
16b-3 promulgated under the "Exchange Act." All references in the Plan to the
"Board" shall mean a Committee or the Board or the executive officer referred to
in Section 3(b) to the extent of such delegation.

4.       STOCK AVAILABLE FOR OPTIONS

         (a) NUMBER OF SHARES. Subject to adjustment under Section 4(c), Options
may be granted under the Plan for up to 2,700,000 shares of Common Stock. If any
Option expires or is terminated, surrendered or canceled without having been
fully exercised or is forfeited in whole or in part or results in any Common
Stock not being issued, the unused Common Stock covered by such Option shall
again be available for the grant of Options under the Plan, subject, however, in
the case of Incentive Stock Options (as defined hereinafter), to any limitation
required under the Code. Shares issued under the Plan may consist in whole or in
part of authorized but unissued shares or treasury shares.

         (b) PER-PARTICIPANT LIMIT. Subject to adjustment under Section 4(c),
for Options granted after the Common Stock is registered under the Exchange Act,
the maximum number of shares with respect to which an Option may be granted to
any Participant under the Plan shall be 500,000 per calendar year. The
per-Participant limit described in this Section 4(b) shall be construed and
applied consistently with Section 162(m) of the Code.

         (c) ADJUSTMENT TO COMMON STOCK. In the event of any stock split, stock
dividend, recapitalization, reorganization, merger, consolidation, combination,
exchange of shares, liquidation, spin-off, or other similar change in
capitalization or event, or any distribution to holders of Common Stock other
than a normal cash dividend, the number and class of security and exercise price
per share subject to each outstanding Option, shall be appropriately adjusted by
the Company (or substituted Options may be made, if applicable) to the extent
the Board shall determine, in good faith, that such an adjustment (or
substitution) is necessary and appropriate. If this Section 4(c) applies and
Section 6(e)(1) applies for any event, Section 6(e)(1) shall be applicable to
such event, and Section 4(c) shall not be applicable.

5.       OPTIONS

         (a) GENERAL. The Board may grant Options and determine the number of
shares of Common Stock to be covered by each Option, the exercise price of each
Option and the conditions and limitations applicable to the exercise of each
Option, including conditions relating to applicable federal or state securities
laws, as it considers necessary or advisable. An Option which is not intended to
be an Incentive Stock Option (as defined hereinafter) shall be designated a
"Nonstatutory Stock Option".


                                      2.


<PAGE>

         (b) INCENTIVE STOCK OPTION. An Option that the Board intends to be an
"incentive stock option" as defined in Section 422 of the Code (an "Incentive
Stock Option") shall only be granted to employees of the Company and shall be
subject to and shall be construed consistently with the requirements of Section
422 of the Code. The Company shall have no liability to a Participant, or any
other party, if an Option (or any part thereof) which is intended to be an
Incentive Stock Option is not an Incentive Stock Option.

         (c) EXERCISE PRICE. The Board shall establish the exercise price at the
time each Option is granted and specify it in the applicable option agreement.

         (d) DURATION OF OPTIONS. Each Option shall be exercisable at such times
and subject to such terms and conditions as the Board may specify in the
applicable option agreement.

         (e) EXERCISE OF OPTION. Options may be exercised only by delivery to
the Company of a written notice of exercise signed by the proper person together
with payment in full as specified in Section 5(f) for the number of shares for
which the Option is exercised.

         (f) PAYMENT UPON EXERCISE. Common Stock purchased upon the exercise of
an Option granted under the Plan shall be paid for as follows:

                  (i) in cash or by check, payable to the order of the Company;

                  (ii) except as the Board may otherwise provide in an Option,
delivery of an irrevocable and unconditional undertaking by a credit worthy
broker to deliver promptly to the Company sufficient funds to pay the exercise
price, or delivery by the Participant to the Company of a copy of irrevocable
and unconditional instructions to a credit worthy broker to deliver promptly to
the Company cash or a check sufficient to pay the exercise price;

                  (iii) to the extent permitted by the Board and explicitly
provided in the Option (i) by delivery of shares of Common Stock owned by the
Participant valued at their fair market value as determined by the Board in good
faith ("Fair Market Value") which Common Stock was owned by the Participant at
least six months prior to such delivery, (ii) by delivery of a promissory note
of the Participant to the Company on terms determined by the Board, or (iii) by
payment of such other lawful consideration as the Board may determine; or

                  (iv) any combination of the above permitted forms of payment.

6.       GENERAL PROVISIONS APPLICABLE TO OPTIONS

         (a) TRANSFERABILITY OF OPTIONS. Except as the Board may otherwise
determine or provide in an Option, Options shall not be sold, assigned,
transferred, pledged or otherwise encumbered by the person to whom they are
granted, either voluntarily or by operation of law, except by will or the laws
of descent and distribution, and, during the life of the Participant, shall be
exercisable only by the Participant. References to Participant, to the extent
relevant in the context, shall include references to authorized transferees.


                                      3.


<PAGE>
 
         (b) DOCUMENTATION. Each Option under the Plan shall be evidenced by a
written instrument in such form as the Board shall determine. Each Option may
contain terms and conditions in addition to those set forth in the Plan.

         (c) BOARD DISCRETION. Except as otherwise provided by the Plan, each
type of Option may be granted alone, in addition to or in relation to any other
Option. The terms of each Option need not be identical, and the Board need not
treat Participants uniformly.

         (d) TERMINATION OF STATUS. The Board shall determine the effect on an
Option of the disability, death, retirement, authorized leave of absence or
other change in the employment or other status of a Participant and the extent
to which, and the period during which, the Participant, the Participant's legal
representative, conservator, guardian or the beneficiary designated by a
Participant, in a manner determined by the Board, to receive amounts due or
exercise rights of the Participant in the event of the Participant's death (the
"Designated Beneficiary") may exercise rights under the Option.

         (e) ACQUISITION EVENTS

                           (1) CONSEQUENCES OF ACQUISITION EVENTS. Upon the
occurrence of an Acquisition Event (as defined below), or the execution by the
Company of any agreement with respect to an Acquisition Event, the Board shall
take either or both of the following actions with respect to then outstanding
Options: (i) provide that outstanding Options shall be assumed, or equivalent
Options shall be substituted, by the acquiring or succeeding corporation (or an
affiliate thereof), provided that any such Options substituted for Incentive
Stock Options shall satisfy, in the determination of the Board, the requirements
of Section 424(a) of the Code; and (ii) upon written notice to the Participants,
provide that all then unexercised Options will become exercisable in full as of
a specified date (the "Acceleration Date") prior to the Acquisition Event and
will terminate immediately prior to the consummation of such Acquisition Event,
except to the extent exercised by the Participants between the Acceleration Date
and the consummation of such Acquisition Event.

         An "Acquisition Event" shall mean: (a) any merger or consolidation
which results in the voting securities of the Company outstanding immediately
prior thereto continuing to represent (either by remaining outstanding or by
being converted into voting securities of the surviving or acquiring entity)
less than 60% of the combined voting power of the voting securities of the
Company or such surviving or acquiring entity outstanding immediately after such
merger or consolidation; (b) any sale of all or substantially all of the assets
of the Company; (c) the complete liquidation of the Company; or (d) the
acquisition of "beneficial ownership" (as defined in Rule 13d-3 under the
Exchange Act) of securities of the Company representing 50% or more of the
combined voting power of the Company's then outstanding securities (other than
through a merger or consolidation or an acquisition of securities directly from
the Company) by any "person", as such term is used in Sections 13(d) and 14(d)
of the Exchange Act other than the Company, any trustee or other fiduciary
holding securities under an employee benefit plan of the Company, or any
corporation owned directly or indirectly by the stockholders of the Company in
substantially the same proportion as their ownership of stock of the Company.


                                      4.


<PAGE>

                           (2) ASSUMPTION OF OPTIONS UPON ACQUISITION EVENT. The
Board may grant Options under the Plan in substitution for stock and stock-based
Options held by employees of another corporation who become employees of the
Company as a result of a merger or consolidation of the employing corporation
with the Company or the acquisition by the Company of property or stock of the
employing corporation. The substitute Options shall be granted on such terms and
conditions as the Board considers appropriate in the circumstances.

         (f) WITHHOLDING. Each Participant shall pay to the Company, or make
provision satisfactory to the Board for payment of, any taxes required by law to
be withheld in connection with Options to such Participant no later than the
date of the event creating the tax liability. The Company may, to the extent
permitted by law, deduct any such tax obligations from any payment of any kind
otherwise due to a Participant.

         (g) AMENDMENT OF OPTION. The Board may amend, modify or terminate any
outstanding Option, including but not limited to, substituting therefor another
Option, changing the date of exercise and converting an Incentive Stock Option
to a Nonstatutory Stock Option, provided that the Participant's consent to such
action shall be required unless the Board determines that the action, taking
into account any related action, would not materially and adversely affect the
Participant.

         (h) CONDITIONS ON DELIVERY OF STOCK. The Company will not be obligated
to deliver any shares of Common Stock pursuant to the Plan or to remove
restrictions from shares previously delivered under the Plan until (i) all
conditions of the Option have been met or removed to the satisfaction of the
Company, (ii) in the opinion of the Company's counsel, all other legal matters
in connection with the issuance and delivery of such shares have been satisfied,
including any applicable securities laws and any applicable stock exchange or
stock market rules and regulations, and (iii) the Participant has executed and
delivered to the Company such representations or agreements as the Company may
consider appropriate to satisfy the requirements of any applicable laws, rules
or regulations.

         (i) ACCELERATION. The Board may at any time provide that any Options
shall become immediately exercisable in full.

7.       MISCELLANEOUS

         (a) NO RIGHT TO EMPLOYMENT OR OTHER STATUS. No person shall have any
claim or right to be granted an Option, and the grant of an Option shall not be
construed as giving a Participant the right to continued employment or any other
relationship with the Company. The Company expressly reserves the right at any
time to dismiss or otherwise terminate its relationship with a Participant free
from any liability or claim under the Plan, except as expressly provided in the
applicable Option.

         (b) NO RIGHTS AS STOCKHOLDER. Subject to the provisions of the
applicable Option, no Participant or Designated Beneficiary shall have any
rights as a stockholder with respect to any shares of Common Stock to be
distributed with respect to an Option until becoming the record holder thereof.


                                     5.


<PAGE>

         (c) EFFECTIVE DATE AND TERM OF PLAN. The Plan shall become effective on
the date on which it is adopted by the Board, but no Option granted to a
Participant designated as subject to Section 162(m) by the Board shall become
exercisable, vested or realizable, as applicable to such Option, unless and
until the Plan has been approved by the Company's stockholders. No Options shall
be granted under the Plan after the completion of ten years from the earlier of
(i) the date on which the Plan was adopted by the Board or (ii) the date the
Plan was approved by the Company's stockholders, but Options previously granted
may extend beyond that date.

         (d) AMENDMENT OF PLAN. The Board may amend, suspend or terminate the
Plan or any portion thereof at any time, provided that no amendment shall be
made without stockholder approval if such approval is necessary to comply with
any applicable tax or regulatory requirements, including any securities laws,
stock exchange or stock market rules. Amendments requiring stockholder approval
shall become effective when adopted by the Board, but no Option granted to a
Participant designated as subject to Section 162(m) by the Board after the date
of such amendment shall become exercisable, realizable or vested, as applicable
to such Option (to the extent that such amendment to the Plan was required to
grant such Option to a particular Participant), unless and until such amendment
shall have been approved by the Company's stockholders.

         (e) STOCKHOLDER APPROVAL. For purposes of this Plan, stockholder
approval shall mean approval by a vote of the stockholders in accordance with
the requirements of Section 162(m) of the Code.

         (f) GOVERNING LAW. The provisions of the Plan and all Options made
hereunder shall be governed by and interpreted in accordance with the laws of
the State of Delaware, without regard to any applicable conflicts of law.


                                      6.


<PAGE>

                           ACADIA Pharmaceuticals Inc.

                        INCENTIVE STOCK OPTION AGREEMENT
                      GRANTED UNDER 1997 STOCK OPTION PLAN

1.       GRANT OF OPTION.

                  This agreement evidences the grant by ACADIA Pharmaceuticals
         Inc., a Delaware corporation (the "Company"), on
         ____________to______________, an employee of the Company (the
         "Participant"), of an option to purchase, in whole or in part, on the
         terms provided herein and in the Company's 1997 Stock Option Plan (the
         "Plan"), a total of _______ shares of common stock, $.0001 par value of
         the Company ("Common Stock") (the "Shares") at $_______ per Share.
         Unless earlier terminated, this option shall expire on __________ (the
         ten years from grant date "Final Exercise Date ").

                  It is intended that the option evidenced by this agreement
         shall be an incentive stock option as defined in Section 422 of the
         Internal Revenue Code of 1986, as amended and any regulations
         promulgated thereunder (the "Code"). Except as otherwise indicated by
         the context, the term "Participant", as used in this option, shall be
         deemed to include any person who acquires the right to exercise this
         option validly under its terms.

2.       VESTING SCHEDULE.

                  This option will become exercisable as to 25% of the original
         number of Shares at the end of the first full 12-month period following
         the date of initial employment with the Company, ________________ (the
         "Employment Date") and as to an additional 25% at each of the second,
         third and fourth anniversaries of the Employment Date.

                  The right of exercise shall be cumulative so that if the
         option is not exercised to the maximum extent permissible it shall
         continue to be exercisable, in whole or in part, with respect to all
         shares for which it is vested which were not so purchased, at any time
         prior to the Final Exercise Date or the earlier termination of this
         option.

3.       EXERCISE OF OPTION.

                  (a) FORM OF EXERCISE. Each election to exercise this option
         shall be in writing, signed by the Participant, and received by the
         Company at its principal office, accompanied by this agreement, and
         payment in full in the manner provided in the Plan. The Participant may
         purchase less than the number of shares covered hereby, provided that
         no partial exercise of this option may be for any fractional share or
         for fewer than ten whole shares.


<PAGE>

                                     - 2 -


                  (b) CONTINUOUS RELATIONSHIP WITH THE COMPANY REQUIRED. Except
         as otherwise provided in this Section 3, this option may not be
         exercised unless the Participant, at the time he or she exercises this
         option, is, and has been at all times since the date of grant of this
         option, an employee, officer or director of, or consultant or advisor
         to, the Company or any parent or subsidiary of the Company as defined
         in Section 424(e) or (f) of the Code (an "Eligible Participant").

                  (c) TERMINATION OF RELATIONSHIP WITH THE COMPANY. If the
         Participant ceases to be an Eligible Participant for any reason, then,
         except as provided in paragraphs (d) and (e) below, the right to
         exercise this option shall terminate three months after such cessation
         (but in no event after the Final Exercise Date), PROVIDED THAT this
         option shall be exercisable only to the extent that the Participant was
         entitled to exercise this option on the date of such cessation.
         Notwithstanding the foregoing, if the Participant, prior to the Final
         Exercise Date, violates the non-competition or confidentiality
         provisions of any employment contract, confidentiality and
         nondisclosure agreement or other agreement between the Participant and
         the Company, the right to exercise this option shall terminate
         immediately upon written notice to the Participant from the Company
         describing such violation.

                  (d) EXERCISE PERIOD UPON DEATH OR DISABILITY. If the
         Participant dies or becomes disabled (within the meaning of Section
         22(e)(3) of the Code) prior to the Final Exercise Date while he or she
         is an Eligible Participant and the Company has not terminated such
         relationship for "cause" as specified in paragraph (e) below, this
         option shall be exercisable, within the period of one year following
         the date of death or disability of the Participant by the Participant,
         PROVIDED THAT this option shall be exercisable only to the extent that
         this option was exercisable by the Participant on the date of his or
         her death or disability, and further provided that this option shall
         not be exercisable after the Final Exercise Date.

                  (e) DISCHARGE FOR CAUSE. If the Participant, prior to the
         Final Exercise Date, is discharged by the Company for "cause" (as
         defined below), the right to exercise this option shall terminate
         immediately upon the effective date of such discharge. "Cause" shall
         mean willful misconduct by the Participant or willful failure to
         perform his or her responsibilities in the best interests of the
         Company (including, without limitation, breach by the Participant of
         any provision of any employment, consulting, advisory, nondisclosure,
         non-competition or other similar agreement between the Participant and
         the Company), as determined by the Company, which determination shall
         be conclusive. The Participant shall be considered to have been
         discharged for "cause" if the Company determines, within 30 days after
         the Participant's resignation, that discharge for cause was warranted.


<PAGE>

                                     - 3 -


4.       RIGHT OF FIRST REFUSAL.

                  (a) If the Participant proposes to sell, assign, transfer,
         pledge, hypothecate or otherwise dispose of, by operation of law or
         otherwise (collectively, "transfer") any Shares acquired upon exercise
         of this option, then the Participant shall first give written notice of
         the proposed transfer (the "Transfer Notice") to the Company. The
         Transfer Notice shall name the proposed transferee and state the number
         of such Shares the Participant proposes to transfer (the "Offered
         Shares"), the price per share and all other material terms and
         conditions of the transfer.

                  (b) For 30 days following its receipt of such Transfer Notice,
         the Company shall have the option to purchase all (but not less than
         all) of the Offered Shares at the price and upon the terms set forth in
         the Transfer Notice. In the event the Company elects to purchase all of
         the Offered Shares, it shall give written notice of such election to
         the Participant within such 30-day period. Within 10 days after his
         receipt of such notice, the Participant shall tender to the Company at
         its principal offices the certificate or certificates representing the
         Offered Shares, duly endorsed in blank by the Participant or with duly
         endorsed stock powers attached thereto, all in a form suitable for
         transfer of the Offered Shares to the Company. Upon receipt of such
         certificate or certificates, the Company shall deliver or mail to the
         Participant a check in payment of the purchase price for the Offered
         Shares; PROVIDED THAT if the terms of payment set forth in the Transfer
         Notice were other than cash against delivery, the Company may pay for
         the Offered Shares on the same terms and conditions as were set forth
         in the Transfer Notice.

                  (c) At the time at which the Offered Shares are required to be
         delivered to the Company for transfer to the Company pursuant to
         subsection (b) above, the Company shall not pay any dividend to the
         Participant on account of such Shares or permit the Participant to
         exercise any of the privileges or rights of a stockholder with respect
         to such Offered Shares, but shall, in so far as permitted by law, treat
         the Company as the owner of such Offered Shares.

                  (d) If the Company does not elect to acquire all of the
         Offered Shares, the Participant may, within the 30-day period following
         the expiration of the option granted to the Company under subsection
         (b) above, transfer the Offered Shares to the proposed transferee,
         PROVIDED THAT such transfer shall not be on terms and conditions more
         favorable to the transferee than those contained in the Transfer
         Notice. Notwithstanding any of the above, all Offered Shares
         transferred pursuant to this Section 4 shall remain subject to the
         right of first refusal set forth in this Section 4 and such transferee
         shall, as a condition to such transfer, deliver to the Company a
         written instrument confirming that such transferee shall be bound by
         all of the terms and conditions of this Section 4.


<PAGE>

                                     - 4 -


                  (e) The following transactions shall be exempt from the
         provisions of this Section 4:

                           (1) any transfer of Shares to or for the benefit of
         any spouse, child or grandchild of the Participant, or to a trust for
         their benefit;

                           (2) any transfer pursuant to an effective
         registration statement filed by the Company under the Securities Act of
         1933, as amended (the "Securities Act"); and

                           (3) any transfer of the Shares pursuant to the sale
         of all or substantially all of the business of the Company;

         PROVIDED, HOWEVER, that in the case of a transfer pursuant to clause 1
         above, such Shares shall remain subject to the right of first refusal
         set forth in this Section 4 and such transferee shall, as a condition
         to such transfer, deliver to the Company a written instrument
         confirming that such transferee shall be bound by all of the terms and
         conditions of this Section 4.

                  (f) The Company may assign its rights to purchase Offered
         Shares in any particular transaction under this Section 4 to one or
         more persons or entities.

                  (g) The provisions of this Section 4 shall terminate upon the
         earlier of the following events:

                           (1) the closing of the sale of shares of Common Stock
         in an underwritten public offering pursuant to an effective
         registration statement filed by the Company under the Securities Act;
         or

                           (2) the sale of all or substantially all of the
         capital stock, assets or business of the Company, by merger,
         consolidation, sale of assets or otherwise.

                  (h) The Company shall not be required (a) to transfer on its
         books any of the Shares which shall have been sold or transferred in
         violation of any of the provisions set forth in this Section 4, or (b)
         to treat as owner of such Shares or to pay dividends to any transferee
         to whom any such Shares shall have been so sold or transferred.


5.       AGREEMENT IN CONNECTION WITH PUBLIC OFFERING.

                  The participant agrees, in connection with the initial
         underwritten public offering of the Company's securities, (i) not to
         sell, make short sale of, loan, grant any options for the 


<PAGE>

                                     - 5 -


         purchase of, or otherwise dispose of any shares of Common Stock held by
         the Participant (other than those shares included in the registration
         statement related to such offering) without the prior written consent
         of the Company or the underwriters managing such initial underwritten
         public offering of the Company's securities for a period of 180 days
         from the effective date of such registration statement, and (ii) to
         execute any agreement reflecting clause (i) above as may be requested
         by the company or underwriters at the time of such initial offering.

6.       WITHHOLDING.

                  No Shares will be issued pursuant to the exercise of this
         option unless and until the Participant pays to the Company, or makes
         provision satisfactory to the Company for payment of, any federal,
         state or local withholding taxes required by law to be withheld in
         respect of this option.

7.       NONTRANSFERABILITY OF OPTION.

                  This option may not be sold, assigned, transferred, pledged or
         otherwise encumbered by the Participant, either voluntarily or by
         operation of law, except by will or the laws of descent and
         distribution, and, during the lifetime of the Participant, this option
         shall be exercisable only by the Participant.

8.       DISQUALIFYING DISPOSITION.

                  If the Participant disposes of Shares acquired upon exercise
         of this option within two years from the date of grant of the option or
         one year after such Shares were acquired pursuant to exercise of this
         option, the Participant shall notify the Company in writing of such
         disposition.

9.        PROVISIONS OF THE PLAN.

                  This option is subject to the provisions of the Plan, a copy
         of which is furnished to the Participant with this option.


<PAGE>

                                     - 6 -


         IN WITNESS WHEREOF, the Company has caused this option to be executed
         under its corporate seal by its duly authorized officer. This option
         shall take effect as a sealed instrument.

         AACADIA Pharmaceuticals Inc.



         Dated: _________  By: ________________________________________________


                               Name:  Uli Hacksell
                               Title: Chief Executive Officer




         PARTICIPANT'S ACCEPTANCE

                  The undersigned hereby accepts the foregoing option and agrees
         to the terms and conditions thereof. The undersigned hereby
         acknowledges receipt of a copy of the Company's 1997 Stock Option Plan.

                                          PARTICIPANT:



                                          ___________________________


                                          Name: _____________________


<PAGE>

                           ACADIA Pharmaceuticals Inc.


                       NONSTATUTORY STOCK OPTION AGREEMENT
          GRANTED TO EMPLOYEES IN DENMARK UNDER 1997 STOCK OPTION PLAN


1.       GRANT OF OPTION.

                  This agreement evidences the grant by ACADIA Pharmaceuticals
         Inc., a Delaware corporation (the "Company"), on (date) to (employee),
         an employee of the Company (the "Participant"), of an option to
         purchase, in whole or in part, on the terms provided herein and in the
         Company's 1997 Stock Option Plan (the "Plan"), a total of (number of
         shares) shares of common stock, $.0001 par value per share, of the
         Company ("Common Stock") (the "Shares") at (FMV of share) per Share.
         Shares issued under this Agreement shall consist of authorized but
         unissued shares of Common Stock of the Company. Except where the
         context otherwise requires, the term "Company" shall include any
         present or future subsidiary corporations of ACADIA Pharmaceuticals
         Inc., as defined in Section 424(f) of the Internal Revenue Code of
         1986, as amended, and any regulations promulgated thereunder (the
         "Code") (a "Subsidiary").

                  It is intended that the option evidenced by this agreement
         shall not be an incentive stock option as defined in Section 422 of the
         Internal Revenue Code of 1986, as amended and any regulations as
         promulgated thereunder (the "Code"). Except as otherwise indicated by
         the context, the term "Participant", as used in this option, shall be
         deemed to include any person who acquires the right to exercise this
         option validly under its terms.

         2.       VESTING SCHEDULE.

                  (a) Subject to Section 2(b) below, this option will become
         exercisable as to 25% of the original number of Shares at the end of
         the first full 18-month period following the date of initial employment
         with the Company, (start date) (the "Employment Date") and as to an
         additional 25% at each of the second, third and fourth anniversaries of
         the Employment Date.

                  The right of exercise shall be cumulative so that if the
         option is not exercised to the maximum extent permissible it shall
         continue to be exercisable, in whole or in part, with respect to all
         shares for which it is vested which were not so purchased, at any time
         prior to the Final Exercise Date (as defined below) or the earlier
         termination of this option (as further described in Section 2(c)
         below).


<PAGE>

                  (b) Notwithstanding Section 2(a) above, this option may not be
         exercised until the first to occur of the following:

                           (1) Immediately prior to the sale of all or
         substantially all of the capital stock, assets or business of the
         Company, by merger, consolidation, sale of assets or otherwise; or

                           (2) Such time following the closing of the sale of
         the shares of Common Stock in an underwritten public offering pursuant
         to an effective registration statement filed by the Company under the
         Securities Act that the shares of Common Stock issuable upon exercise
         of this option are freely tradeable and free of restrictions on
         transfer (whether imposed by law, including without limitation
         securities law, contract, Company policy or otherwise).

                  (c) Notwithstanding 2(b) above, this option, if not sooner
         exercisable in accordance with 2(a) and (b) above, will become
         exercisable as to 100% of the original number of Shares at the end of
         the eight year period following the Employment Date if the employee is
         continuously employed with the Company for such eight year period.

                  (d) Unless earlier terminated, this option shall expire on
         (date ten years from date of grant) (the "Final Exercise Date"). In
         addition, each portion of this Option exercisable pursuant to this
         Section 2 shall terminate at the end of the first full year following
         the date that it first becomes exercisable.

         3.       EXERCISE OF OPTION.

                  (a) FORM OF EXERCISE. Each election to exercise this option
         shall be in writing, signed by the Participant, and received by the
         Company at its principal office, accompanied by this agreement, and
         payment in full in the manner provided in the Plan. The Participant may
         purchase less than the number of shares covered hereby, provided that
         no partial exercise of this option may be for any fractional share or
         for fewer than ten whole shares.

                  (b) CONTINUOUS RELATIONSHIP WITH THE COMPANY REQUIRED FOR
         CONTINUED VESTING. If the Participant ceases to be an employee, officer
         or director of, or consultant or advisor to, the Company or any
         subsidiary of the Company as defined in Section 424(e) or (f) of the
         Code (an "Eligible Participant"), then in addition to the other
         restrictions on exercise contained herein, this option shall be
         exercisable only to the extent that the Participant was entitled to
         exercise this option on the date of such cessation.


<PAGE>

                  (c) VIOLATION OF AGREEMENT WITH THE COMPANY. Notwithstanding
         the foregoing, if the Participant, prior to the Final Exercise Date,
         violates the non-competition or confidentiality provisions of any
         employment contract, confidentiality and nondisclosure agreement or
         other agreement between the Participant and the Company, the right to
         exercise this option shall terminate immediately upon written notice to
         the Participant from the Company describing such violation.

                  (d) DISCHARGE FOR CAUSE. If the Participant, prior to the
         Final Exercise Date, is discharged by the Company for "cause" (as
         defined below or, if the Participant has entered into an employment or
         other such agreement with the Company pursuant to which "Cause" is
         defined, then "Cause" shall have the meaning set forth in such
         Agreement), the right to exercise this option shall terminate
         immediately upon the effective date of such discharge. "Cause" shall
         mean willful misconduct by the Participant or willful failure to
         perform his or her responsibilities in the best interests of the
         Company (including, without limitation, breach by the Participant of
         any provision of any employment, consulting, advisory, nondisclosure,
         non-competition or other similar agreement between the Participant and
         the Company), as determined by the Company, which determination shall
         be conclusive. The Participant shall be considered to have been
         discharged for "cause" if the Company determines, within 30 days after
         the Participant's resignation, that discharge for cause was warranted.

         4.       AGREEMENT IN CONNECTION WITH PUBLIC OFFERING.

                  The Participant agrees, in connection with the initial
         underwritten public offering of the Company's securities, (i) not to
         sell, make short sale of, loan, grant any options for the purchase of,
         or otherwise dispose of any shares of Common Stock held by the
         Participant (other than those shares included in the registration
         statement related to such offering) without the prior written consent
         of the Company or the underwriters managing such initial underwritten
         public offering of the Company's securities for a period of 180 days
         from the effective date of such registration statement, and (ii) to
         execute any agreement reflecting clause (i) above as may be requested
         by the Company or underwriters at the time of such offering.

         5.       COME-ALONG OBLIGATIONS

                  (a) GENERALLY. The Participant hereby agrees, if requested by
         a Significant Number of Major Stockholders (as defined in the
         Stockholders Agreement (the "Stockholders Agreement") entered into by
         the Company and certain investors in connection with the sale by the
         Company of shares of its Series B Preferred Stock (the Stockholders
         constituting such significant Number of Major Stockholders are
         hereinafter referred to as the "Come-Along Stockholders"), to sell all
         of his or her Shares and other securities in the 


<PAGE>

         Company to any other Person (the "Proposed Buyer") in the manner and on
         the terms set forth in this Section 5 in connection with the sale by
         the Come-Along Stockholders to the Proposed Buyer of all of the shares
         and other securities in the Company of the Come-Along Stockholders.
         Notwithstanding the foregoing, the provisions of this Section 5 shall
         not apply if the Proposed Buyer is an affiliate of any stockholder
         which comprises a part of the Come-Along Stockholders.

                  (b) NOTICE. A "Come-Along Notice" shall be delivered by a
         stockholder which is a part of the Come-Along Stockholders on behalf of
         all such stockholders to the Participant. The Come-Along Notice shall
         set forth the principal terms of the proposed purchase (the "Come-Along
         Transaction") insofar as it relates to the Shares and other securities
         in the Company, the purchase price, the name and address of the
         Proposed Buyer and the other principal terms of the proposed Come-Along
         Transaction. The price for the Participant's Shares and other
         securities in the Company shall be equal to the per share price
         applicable to the Come-Along Transaction, provided, however, that any
         stockholder which is a "Stockholder" under the Stockholders Agreement
         (an "Agreement Stockholder") may demand that the proceeds from the
         Come-Along Transaction are reallocated among the Agreement Stockholders
         such that the Agreement Stockholders shall be entitled to receive such
         portion of the proceeds as if the proceeds were distributed pursuant to
         Section 2(a) of Article Fourth of the Company's Certificate of
         Incorporation and provided further that such Agreement Stockholders who
         tender securities which represent the right to purchase shares shall be
         entitled to receive as consideration therefor the value of such shares
         (determined on the basis of the terms and conditions applicable to the
         Come-Along Transaction taking into account the reallocation of the
         purchase price as aforesaid) purchasable on the exercise thereof less
         the exercise price, if any, of the applicable security.

                  (c) CLOSING.

                           (i) If the Come-Along Stockholders consummate the
         Come-Along Transaction, the Participant shall be bound and obligated to
         sell all of his or her Shares and other securities in the Company in
         the Come-Along Transaction on the same terms and conditions as the
         Come-Along Stockholders sell their securities in the Company
         (including, without limitation, an agreement to be liable, on a pro
         rata basis in accordance with the proceeds received, in respect of any
         representations, warranties and indemnities reasonably given in the
         Come-Along Transaction by the Come-Along Stockholders). The Participant
         agrees that he or she will also take such actions and execute such
         documents and instruments as shall be necessary or desirable in order
         to consummate the Come-Along Transaction expeditiously. If at the end
         of the one hundred eightieth (180th) day following the date of the
         Come-Along Notice the Come-Along Transaction has not been completed,
         the Participant shall be released from his or her obligations under the
         Come-Along Notice, the Come-


<PAGE>

         Along Notice shall be null and void, and it shall be necessary for a
         separate Come-Along Notice to have been furnished and the terms and
         provisions of this Section 5 separately complied with, in order to
         consummate a Come-Along Transaction pursuant to this Section 5. All
         costs and expenses incurred by the Participant in connection with any
         proposed Come-Along Transaction as to which a Come-Along Notice shall
         have been properly given (whether or not consummated), including
         without limitation all attorneys' fees and disbursements, all
         accounting fees and disbursements and all finders' or brokerage fees or
         commissions, shall be paid by the Company.

                           (ii) Notwithstanding any other provision of this
         Agreement, in the event the consideration to be paid in exchange for
         Shares and other securities in the Company in the proposed Come-Along
         Transaction includes any securities and the receipt thereof by a
         Participant would require under applicable law (A) the registration or
         qualification of such securities or of any person as a broker or dealer
         or agent with respect to such securities or (B) the provision to any
         participant in the Come-Along Transaction of any information other than
         such information as would be required under Regulation D of the
         Securities and Exchange Commission in an offering made pursuant to said
         Regulation D solely to "accredited investors" and defined in said
         Regulation D, the stockholders comprising the Come-Along Stockholders
         shall have no obligation to cause the Participant to receive as to each
         share and other securities in the Company the same amount and kind of
         securities as the Come-Along Stockholders to the extent of such receipt
         of securities, unless the Come-Along Stockholders shall have elected to
         cause such requirements to have been complied with to the extent
         necessary to permit the Participant to receive such securities. The
         Participant shall be entitled to receive, in lieu thereof, against
         surrender of the shares and other securities in the Company which would
         have otherwise been transferred by the Participant to the Proposed
         Buyer in the Come-Along Transaction, an amount in cash equal to the
         fair market value of the securities which the Participant would
         otherwise have received (as determined in good faith by the Board of
         Directors of the Company in its sole discretion). In the event such
         requirements have been complied with to the extent necessary to permit
         the Participant to receive such securities, the Participant shall
         execute such documents and instruments, and take such other actions
         (including without limitation, if required by the Come-Along
         Stockholders, agreeing to be represented, without cost to the
         Participant, during the course of such Come-Along Transaction by a
         "purchaser representative" (as defined in Regulation D) in connection
         with evaluating the merits and risks of the prospective investment and
         acknowledging that he or she was so represented), as the Proposed Buyer
         or the Company shall reasonably request in order to permit such
         requirements to have been complied with; PROVIDED, HOWEVER, that such
         actions shall not include any expenditure of funds by the Participant,
         it being understood that payment by the Participant of the fees and
         disbursements of any counsel the Participant may elect to retain shall
         be deemed not to constitute a required expenditure of funds for
         purposes of this provision.


<PAGE>

                           (iii) At the closing of any Come-Along Transaction
         under this Section 5, the Participant shall deliver the Shares and
         other securities in the Company to be sold by him or her, duly endorsed
         for transfer with signature guaranteed, free and clear of any liens,
         with any stock transfer tax stamps affixed, against delivery of the
         applicable purchase price.



                  (d)      MISCELLANEOUS

                           (i) LEGEND. The following legend shall appear on the
         back of any certificate for Shares issued by the Company to the
         Participant:

                           The shares represented by this Certificate are
                  subject to the terms of a Come-Along Agreement among the
                  Company and the holder of this Certificate. Any purchaser,
                  assignee, transferee, pledgee or other successor to any holder
                  hereof is bound by the terms of such Agreement, a copy of
                  which will be mailed, without charge, within five (5) days
                  after receipt of a written request therefor directed to the
                  Secretary of the Company.

                           (ii) AMENDMENT; TERMINATION. This Section 5 shall 
         terminate and be of no further force and effect upon the closing of a 
         Qualifying IPO (as defined in the Stockholders Agreement).

                           (iii) ARBITRATION. Any dispute, controversy or
         difference arising between the parties out of or in relation to or in
         connection with this Section 5 or any breach thereof which cannot be
         settled between the parties shall be finally settled under the Rules of
         Conciliation and Arbitration of the International Chamber of Commerce
         (the "ICC") by which each party agrees to be bound. In any arbitration
         pursuant to this Section the decision shall be rendered by three
         independent arbitrators who shall be appointed by the ICC whose
         decision shall be binding. The seat of arbitration shall be London,
         England. The language of the arbitration shall be English.


                  6.       WITHHOLDING.

                           No Shares will be issued pursuant to the exercise of
         this option unless and until the Participant pays to the Company, or
         makes provision satisfactory to the Company for payment of, any
         federal, state or local withholding taxes required by law to be
         withheld in respect of this option.


<PAGE>

                  7.       NONTRANSFERABILITY OF OPTION.

                           This option may not be sold, assigned, transferred,
         pledged or otherwise encumbered by the Participant, either voluntarily
         or by operation of law, except by will or the laws of descent and
         distribution, and, during the lifetime of the Participant, this option
         shall be exercisable only by the Participant.

                  8.       PROVISIONS OF THE PLAN.

                           This option is subject to the provisions of the Plan,
         a copy of which is furnished to the Participant with this option.

                           IN WITNESS WHEREOF, the Company has caused this
         option to be executed under its corporate seal by its duly authorized
         officer. This option shall take effect as a sealed instrument.

         ACADIA Pharmaceuticals Inc.


                  Dated: _________  By:________________________________________

                                       Name:   Leonard R. Borrmann
                                       Title:  Chief Executive Officer





                            PARTICIPANT'S ACCEPTANCE

                           The undersigned hereby accepts the foregoing option
         and agrees to the terms and conditions thereof. The undersigned hereby
         acknowledges receipt of a copy of the Company's 1997 Stock Option Plan.

                                            PARTICIPANT:


                                            ___________________________________
                                            Name: Employee name





<PAGE>

                           ACADIA PHARMACEUTICALS INC.

                           2000 EQUITY INCENTIVE PLAN


                            ADOPTED DECEMBER 20, 2000
                 APPROVED BY STOCKHOLDERS _______________, 200__
                      TERMINATION DATE: DECEMBER 19, 2010


1.       PURPOSES.

         (a) ELIGIBLE STOCK AWARD RECIPIENTS. The persons eligible to receive
Stock Awards are the Employees, Directors and Consultants of the Company and its
Affiliates.

         (b) AVAILABLE STOCK AWARDS. The purpose of the Plan is to provide a
means by which eligible recipients of Stock Awards may be given an opportunity
to benefit from increases in value of the Common Stock through the granting of
the following Stock Awards: (i) Incentive Stock Options, (ii) Nonstatutory Stock
Options, (iii) stock bonuses and (iv) rights to acquire restricted stock.

         (c) GENERAL PURPOSE. The Company, by means of the Plan, seeks to retain
the services of the group of persons eligible to receive Stock Awards, to secure
and retain the services of new members of this group and to provide incentives
for such persons to exert maximum efforts for the success of the Company and its
Affiliates.

2.       DEFINITIONS.

         (a) "AFFILIATE" means any parent corporation or subsidiary corporation
of the Company, whether now or hereafter existing, as those terms are defined in
Sections 424(e) and (f), respectively, of the
 Code.

         (b) "ANNUAL MEETING" means the annual meeting of the stockholders of
the Company.

         (c) "BOARD" means the Board of Directors of the Company.

         (d) "CODE" means the Internal Revenue Code of 1986, as amended.

         (e) "COMMITTEE" means a committee of one or more members of the Board
appointed by the Board in accordance with subsection 3(c).

         (f) "COMMON STOCK" means the common stock of the Company.

         (g) "COMPANY" means ACADIA Pharmaceuticals Inc., a Delaware
corporation.

         (h) "CONSULTANT" means any person, including an advisor, (i) engaged by
the Company or an Affiliate to render consulting or advisory services and who is
compensated for 


                                       1.

<PAGE>

such services or (ii) who is a member of the Board of Directors of an Affiliate.
However, the term "Consultant" shall not include either Directors who are not
compensated by the Company for their services as Directors or Directors who are
merely paid a director's fee by the Company for their services as Directors.

         (i) "CONTINUOUS SERVICE" means that the Participant's service with the
Company or an Affiliate, whether as an Employee, Director or Consultant, is not
interrupted or terminated. The Participant's Continuous Service shall not be
deemed to have terminated merely because of a change in the capacity in which
the Participant renders service to the Company or an Affiliate as an Employee,
Consultant or Director or a change in the entity for which the Participant
renders such service, provided that there is no interruption or termination of
the Participant's Continuous Service. For example, a change in status from an
Employee of the Company to a Consultant of an Affiliate or a Director will not
constitute an interruption of Continuous Service. The Board or the chief
executive officer of the Company, in that party's sole discretion, may determine
whether Continuous Service shall be considered interrupted in the case of any
leave of absence approved by that party, including sick leave, military leave or
any other personal leave.

         (j) "COVERED EMPLOYEE" means the chief executive officer and the four
(4) other highest compensated officers of the Company for whom total
compensation is required to be reported to stockholders under the Exchange Act,
as determined for purposes of Section 162(m) of the Code.

         (k) "DIRECTOR" means a member of the Board of Directors of the Company.

         (l) "DISABILITY" means the permanent and total disability of a person
within the meaning of Section 22(e)(3) of the Code.

         (m) "EMPLOYEE" means any person employed by the Company or an
Affiliate. Mere service as a Director or payment of a director's fee by the
Company or an Affiliate shall not be sufficient to constitute "employment" by
the Company or an Affiliate.

         (n) "EXCHANGE ACT" means the Securities Exchange Act of 1934, as
amended.

         (o) "FAIR MARKET VALUE" means, as of any date, the value of the Common
Stock determined as follows:

                  (i) If the Common Stock is listed on any established stock
exchange or traded on the Nasdaq National Market or the Nasdaq SmallCap Market,
the Fair Market Value of a share of Common Stock shall be the closing sales
price for such stock (or the closing bid, if no sales were reported) as quoted
on such exchange or market (or the exchange or market with the greatest volume
of trading in the Common Stock) on the last market trading day prior to the day
of determination, as reported in THE WALL STREET JOURNAL or such other source as
the Board deems reliable.

                  (ii) In the absence of such markets for the Common Stock, the
Fair Market Value shall be determined in good faith by the Board.


                                       2.

<PAGE>

         (p) "INCENTIVE STOCK OPTION" means an Option intended to qualify as an
incentive stock option within the meaning of Section 422 of the Code and the
regulations promulgated thereunder.

         (q) "NON-EMPLOYEE DIRECTOR" means a Director who either (i) is not a
current Employee or Officer of the Company or its parent or a subsidiary, does
not receive compensation (directly or indirectly) from the Company or its parent
or a subsidiary for services rendered as a consultant or in any capacity other
than as a Director (except for an amount as to which disclosure would not be
required under Item 404(a) of Regulation S-K promulgated pursuant to the
Securities Act ("Regulation S-K")), does not possess an interest in any other
transaction as to which disclosure would be required under Item 404(a) of
Regulation S-K and is not engaged in a business relationship as to which
disclosure would be required under Item 404(b) of Regulation S-K; or (ii) is
otherwise considered a "non-employee director" for purposes of Rule 16b-3.

         (r) "NONSTATUTORY STOCK OPTION" means an Option not intended to qualify
as an Incentive Stock Option.

         (s) "OFFICER" means a person who is an officer of the Company within
the meaning of Section 16 of the Exchange Act and the rules and regulations
promulgated thereunder.

         (t) "OPTION" means an Incentive Stock Option or a Nonstatutory Stock
Option granted pursuant to the Plan.

         (u) "OPTION AGREEMENT" means a written agreement between the Company
and an Optionholder evidencing the terms and conditions of an individual Option
grant. Each Option Agreement shall be subject to the terms and conditions of the
Plan.

         (v) "OPTIONHOLDER" means a person to whom an Option is granted pursuant
to the Plan or, if applicable, such other person who holds an outstanding
Option.

         (w) "OUTSIDE DIRECTOR" means a Director who either (i) is not a current
employee of the Company or an "affiliated corporation" (within the meaning of
Treasury Regulations promulgated under Section 162(m) of the Code), is not a
former employee of the Company or an "affiliated corporation" receiving
compensation for prior services (other than benefits under a tax qualified
pension plan), was not an officer of the Company or an "affiliated corporation"
at any time and is not currently receiving direct or indirect remuneration from
the Company or an "affiliated corporation" for services in any capacity other
than as a Director or (ii) is otherwise considered an "outside director" for
purposes of Section 162(m) of the Code.

         (x) "PARTICIPANT" means a person to whom a Stock Award is granted
pursuant to the Plan or, if applicable, such other person who holds an
outstanding Stock Award.

         (y) "PLAN" means this ACADIA Pharmaceuticals Inc. 2000 Equity Incentive
Plan.

         (z) "RULE 16b-3" means Rule 16b-3 promulgated under the Exchange Act or
any successor to Rule 16b-3, as in effect from time to time.

         (aa) "SECURITIES ACT" means the Securities Act of 1933, as amended.


                                       3.

<PAGE>

         (bb) "STOCK AWARD" means any right granted under the Plan, including an
Option, a stock bonus and a right to acquire restricted stock.

         (cc) "STOCK AWARD AGREEMENT" means a written agreement between the
Company and a holder of a Stock Award evidencing the terms and conditions of an
individual Stock Award grant. Each Stock Award Agreement shall be subject to the
terms and conditions of the Plan.

         (dd) "TEN PERCENT STOCKHOLDER" means a person who owns (or is deemed to
own pursuant to Section 424(d) of the Code) stock possessing more than ten
percent (10%) of the total combined voting power of all classes of stock of the
Company or of any of its Affiliates.

3.       ADMINISTRATION.

         (a) ADMINISTRATION BY BOARD. The Board shall administer the Plan unless
and until the Board delegates administration to a Committee, as provided in
subsection 3(c).

         (b) POWERS OF BOARD. The Board shall have the power, subject to, and
within the limitations of, the express provisions of the Plan:

                  (i) To determine from time to time which of the persons
eligible under the Plan shall be granted Stock Awards; when and how each Stock
Award shall be granted; what type or combination of types of Stock Award shall
be granted; the provisions of each Stock Award granted (which need not be
identical), including the time or times when a person shall be permitted to
receive Common Stock pursuant to a Stock Award; and the number of shares of
Common Stock with respect to which a Stock Award shall be granted to each such
person.

                  (ii) To construe and interpret the Plan and Stock Awards
granted under it, and to establish, amend and revoke rules and regulations for
its administration. The Board, in the exercise of this power, may correct any
defect, omission or inconsistency in the Plan or in any Stock Award Agreement,
in a manner and to the extent it shall deem necessary or expedient to make the
Plan fully effective.

                  (iii) To amend the Plan or a Stock Award as provided in
Section 12.

                  (iv) Generally, to exercise such powers and to perform such
acts as the Board deems necessary or expedient to promote the best interests of
the Company which are not in conflict with the provisions of the Plan.

         (c) DELEGATION TO COMMITTEE.

                  (i) GENERAL. The Board may delegate administration of the Plan
to a Committee or Committees of one (1) or more members of the Board, and the
term "Committee" shall apply to any person or persons to whom such authority has
been delegated. If administration is delegated to a Committee, the Committee
shall have, in connection with the administration of the Plan, the powers
theretofore possessed by the Board, including the power to delegate to a
subcommittee any of the administrative powers the Committee is authorized to
exercise (and references in this Plan to the Board shall thereafter be to the
Committee or subcommittee), subject, however, to such resolutions, not
inconsistent with the provisions of the 


                                       4.

<PAGE>

Plan, as may be adopted from time to time by the Board. The Board may abolish
the Committee at any time and revest in the Board the administration of the
Plan.

                  (ii) COMMITTEE COMPOSITION WHEN COMMON STOCK IS PUBLICLY
TRADED. At such time as the Common Stock is publicly traded, in the discretion
of the Board, a Committee may consist solely of two or more Outside Directors,
in accordance with Section 162(m) of the Code, and/or solely of two or more
Non-Employee Directors, in accordance with Rule 16b-3. Within the scope of such
authority, the Board or the Committee may (1) delegate to a committee of one or
more members of the Board who are not Outside Directors the authority to grant
Stock Awards to eligible persons who are either (a) not then Covered Employees
and are not expected to be Covered Employees at the time of recognition of
income resulting from such Stock Award or (b) not persons with respect to whom
the Company wishes to comply with Section 162(m) of the Code and/or (2) delegate
to a committee of one or more members of the Board who are not Non-Employee
Directors the authority to grant Stock Awards to eligible persons who are not
then subject to Section 16 of the Exchange Act.

         (d) EFFECT OF BOARD'S DECISION. All determinations, interpretations and
constructions made by the Board in good faith shall not be subject to review by
any person and shall be final, binding and conclusive on all persons.

4.       SHARES SUBJECT TO THE PLAN.
         (a) SHARE RESERVE. Subject to the provisions of Section 11 relating to
adjustments upon changes in Common Stock, the Common Stock that may be issued
pursuant to Stock Awards shall not exceed in the aggregate Two Million Nine
Hundred Two Thousand Eight Hundred Eighty-Three (2,902,883) shares of Common
Stock, plus an annual increase to be added on the day of each Annual Meeting
beginning in 2002 equal to the least of the following amounts: (i) five percent
(5%) of the Company's outstanding shares on the record date for the Annual
Meeting (rounded to the nearest whole share), (ii) 1,500,000 shares of Common
Stock, or (iii) an amount determined by the Board; PROVIDED, HOWEVER, that there
shall be subtracted from this number shares outstanding pursuant to option
exercises (both before and after the adoption of this Plan) under the Company's
1997 Stock Option Plan.

         (b) REVERSION OF SHARES TO THE SHARE RESERVE. If any Stock Award under
this Plan shall for any reason expire or otherwise terminate, in whole or in
part, without having been exercised in full, the shares of Common Stock not
acquired under such Stock Award shall revert to and again become available for
issuance under this Plan.

         (c) SOURCE OF SHARES. The shares of Common Stock subject to the Plan
may be unissued shares or reacquired shares, bought on the market or otherwise.

5.       ELIGIBILITY.

         (a) ELIGIBILITY FOR SPECIFIC STOCK AWARDS. Incentive Stock Options may
be granted only to Employees. Stock Awards other than Incentive Stock Options
may be granted to Employees, Directors and Consultants.


                                       5.

<PAGE>

         (b) TEN PERCENT STOCKHOLDERS. A Ten Percent Stockholder shall not be
granted an Incentive Stock Option unless the exercise price of such Option is at
least one hundred ten percent (110%) of the Fair Market Value of the Common
Stock at the date of grant and the Option is not exercisable after the
expiration of five (5) years from the date of grant.

         (c) SECTION 162(m) LIMITATION. Subject to the provisions of Section 11
relating to adjustments upon changes in the shares of Common Stock, no Employee
shall be eligible to be granted Options covering more than One Million
(1,000,000) shares of Common Stock during any calendar year.

         (d) CONSULTANTS.

                  (i) A Consultant shall not be eligible for the grant of a
Stock Award if, at the time of grant, a Form S-8 Registration Statement under
the Securities Act ("Form S-8") is not available to register either the offer or
the sale of the Company's securities to such Consultant because of the nature of
the services that the Consultant is providing to the Company, or because the
Consultant is not a natural person, or as otherwise provided by the rules
governing the use of Form S-8, unless the Company determines both (i) that such
grant (A) shall be registered in another manner under the Securities Act (E.G.,
on a Form S-3 Registration Statement) or (B) does not require registration under
the Securities Act in order to comply with the requirements of the Securities
Act, if applicable, and (ii) that such grant complies with the securities laws
of all other relevant jurisdictions.

                  (ii) Form S-8 generally is available to consultants and
advisors only if (i) they are natural persons; (ii) they provide bona fide
services to the issuer, its parents, its majority-owned subsidiaries; and (iii)
the services are not in connection with the offer or sale of securities in a
capital-raising transaction, and do not directly or indirectly promote or
maintain a market for the issuer's securities.

6.       OPTION PROVISIONS.

         Each Option shall be in such form and shall contain such terms and
conditions as the Board shall deem appropriate. All Options shall be separately
designated Incentive Stock Options or Nonstatutory Stock Options at the time of
grant, and, if certificates are issued, a separate certificate or certificates
will be issued for shares of Common Stock purchased on exercise of each type of
Option. The provisions of separate Options need not be identical, but each
Option shall include (through incorporation of provisions hereof by reference in
the Option or otherwise) the substance of each of the following provisions:

         (a) TERM. Subject to the provisions of subsection 5(b) regarding Ten
Percent Stockholders, no Incentive Stock Option shall be exercisable after the
expiration of ten (10) years from the date it was granted.

         (b) EXERCISE PRICE OF AN INCENTIVE STOCK OPTION. Subject to the
provisions of subsection 5(b) regarding Ten Percent Stockholders, the exercise
price of each Incentive Stock Option shall be not less than one hundred percent
(100%) of the Fair Market Value of the Common Stock subject to the Option on the
date the Option is granted. Notwithstanding the foregoing, an Incentive Stock
Option may be granted with an exercise price lower than that set 


                                       6.

<PAGE>

forth in the preceding sentence if such Option is granted pursuant to an
assumption or substitution for another option in a manner satisfying the
provisions of Section 424(a) of the Code.

         (c) EXERCISE PRICE OF A NONSTATUTORY STOCK OPTION. The exercise price
of each Nonstatutory Stock Option shall be not less than eighty-five percent
(85%) of the Fair Market Value of the Common Stock subject to the Option on the
date the Option is granted. Notwithstanding the foregoing, a Nonstatutory Stock
Option may be granted with an exercise price lower than that set forth in the
preceding sentence if such Option is granted pursuant to an assumption or
substitution for another option in a manner satisfying the provisions of Section
424(a) of the Code.

         (d) CONSIDERATION. The purchase price of Common Stock acquired pursuant
to an Option shall be paid, to the extent permitted by applicable statutes and
regulations, either (i) in cash at the time the Option is exercised or (ii) at
the discretion of the Board at the time of the grant of the Option (or
subsequently in the case of a Nonstatutory Stock Option) (1) by delivery to the
Company of other Common Stock, (2) according to a deferred payment or other
similar arrangement with the Optionholder or (3) in any other form of legal
consideration that may be acceptable to the Board. Unless otherwise specifically
provided in the Option, the purchase price of Common Stock acquired pursuant to
an Option that is paid by delivery to the Company of other Common Stock
acquired, directly or indirectly from the Company, shall be paid only by shares
of the Common Stock of the Company that have been held for more than six (6)
months (or such longer or shorter period of time required to avoid a charge to
earnings for financial accounting purposes). At any time that the Company is
incorporated in Delaware, payment of the Common Stock's "par value," as defined
in the Delaware General Corporation Law, shall not be made by deferred payment.

         In the case of any deferred payment arrangement, interest shall be
compounded at least annually and shall be charged at the market rate of interest
necessary to avoid a charge to earnings for financial accounting purposes.

         (e) TRANSFERABILITY OF AN INCENTIVE STOCK OPTION. An Incentive Stock
Option shall not be transferable except by will or by the laws of descent and
distribution and shall be exercisable during the lifetime of the Optionholder
only by the Optionholder. Notwithstanding the foregoing, the Optionholder may,
by delivering written notice to the Company, in a form satisfactory to the
Company, designate a third party who, in the event of the death of the
Optionholder, shall thereafter be entitled to exercise the Option.

         (f) TRANSFERABILITY OF A NONSTATUTORY STOCK OPTION. A Nonstatutory
Stock Option shall be transferable to the extent provided in the Option
Agreement. If the Nonstatutory Stock Option does not provide for
transferability, then the Nonstatutory Stock Option shall not be transferable
except by will or by the laws of descent and distribution and shall be
exercisable during the lifetime of the Optionholder only by the Optionholder.
Notwithstanding the foregoing, the Optionholder may, by delivering written
notice to the Company, in a form satisfactory to the Company, designate a third
party who, in the event of the death of the Optionholder, shall thereafter be
entitled to exercise the Option.


                                       7.

<PAGE>

         (g) VESTING GENERALLY. The total number of shares of Common Stock
subject to an Option may, but need not, vest and therefore become exercisable in
periodic installments that may, but need not, be equal. The Option may be
subject to such other terms and conditions on the time or times when it may be
exercised (which may be based on performance or other criteria) as the Board may
deem appropriate. The vesting provisions of individual Options may vary. The
provisions of this subsection 6(g) are subject to any Option provisions
governing the minimum number of shares of Common Stock as to which an Option may
be exercised.

         (h) TERMINATION OF CONTINUOUS SERVICE. In the event an Optionholder's
Continuous Service terminates (other than upon the Optionholder's death or
Disability), the Optionholder may exercise his or her Option (to the extent that
the Optionholder was entitled to exercise such Option as of the date of
termination) but only within such period of time ending on the earlier of (i)
the date three (3) months following the termination of the Optionholder's
Continuous Service (or such longer or shorter period specified in the Option
Agreement), or (ii) the expiration of the term of the Option as set forth in the
Option Agreement. If, after termination, the Optionholder does not exercise his
or her Option within the time specified in the Option Agreement, the Option
shall terminate.

         (i) EXTENSION OF TERMINATION DATE. An Optionholder's Option Agreement
may also provide that if the exercise of the Option following the termination of
the Optionholder's Continuous Service (other than upon the Optionholder's death
or Disability) would be prohibited at any time solely because the issuance of
shares of Common Stock would violate the registration requirements under the
Securities Act, then the Option shall terminate on the earlier of (i) the
expiration of the term of the Option set forth in subsection 6(a) or (ii) the
expiration of a period of three (3) months after the termination of the
Optionholder's Continuous Service during which the exercise of the Option would
not be in violation of such registration requirements.

         (j) DISABILITY OF OPTIONHOLDER. In the event that an Optionholder's
Continuous Service terminates as a result of the Optionholder's Disability, the
Optionholder may exercise his or her Option (to the extent that the Optionholder
was entitled to exercise such Option as of the date of termination), but only
within such period of time ending on the earlier of (i) the date twelve (12)
months following such termination (or such longer or shorter period specified in
the Option Agreement) or (ii) the expiration of the term of the Option as set
forth in the Option Agreement. If, after termination, the Optionholder does not
exercise his or her Option within the time specified herein, the Option shall
terminate.

         (k) DEATH OF OPTIONHOLDER. In the event (i) an Optionholder's
Continuous Service terminates as a result of the Optionholder's death or (ii)
the Optionholder dies within the period (if any) specified in the Option
Agreement after the termination of the Optionholder's Continuous Service for a
reason other than death, then the Option may be exercised (to the extent the
Optionholder was entitled to exercise such Option as of the date of death) by
the Optionholder's estate, by a person who acquired the right to exercise the
Option by bequest or inheritance or by a person designated to exercise the
Option upon the Optionholder's death pursuant to subsection 6(e) or 6(f), but
only within the period ending on the earlier of (1) the date eighteen (18)
months following the date of death (or such longer or shorter period specified
in the Option Agreement) or (2) the expiration of the term of such Option as set
forth in the Option 


                                       8.

<PAGE>

Agreement. If, after death, the Option is not exercised within the time
specified herein, the Option shall terminate.

         (l) EARLY EXERCISE. The Option may, but need not, include a provision
whereby the Optionholder may elect at any time before the Optionholder's
Continuous Service terminates to exercise the Option as to any part or all of
the shares of Common Stock subject to the Option prior to the full vesting of
the Option. Any unvested shares of Common Stock so purchased may be subject to a
repurchase option in favor of the Company or to any other restriction the Board
determines to be appropriate.

7.       PROVISIONS OF STOCK AWARDS OTHER THAN OPTIONS.

         (a) STOCK BONUS AWARDS. Each stock bonus agreement shall be in such
form and shall contain such terms and conditions as the Board shall deem
appropriate. The terms and conditions of stock bonus agreements may change from
time to time, and the terms and conditions of separate stock bonus agreements
need not be identical, but each stock bonus agreement shall include (through
incorporation of provisions hereof by reference in the agreement or otherwise)
the substance of each of the following provisions:

                  (i) CONSIDERATION. A stock bonus may be awarded in
consideration for past services actually rendered to the Company or an Affiliate
for its benefit.

                  (ii) VESTING. Shares of Common Stock awarded under the stock
bonus agreement may, but need not, be subject to a share repurchase option in
favor of the Company in accordance with a vesting schedule to be determined by
the Board.

                  (iii) TERMINATION OF PARTICIPANT'S CONTINUOUS SERVICE. In the
event a Participant's Continuous Service terminates, the Company may reacquire
any or all of the shares of Common Stock held by the Participant which have not
vested as of the date of termination under the terms of the stock bonus
agreement.

                  (iv) TRANSFERABILITY. Rights to acquire shares of Common Stock
under the stock bonus agreement shall be transferable by the Participant only
upon such terms and conditions as are set forth in the stock bonus agreement, as
the Board shall determine in its discretion, so long as Common Stock awarded
under the stock bonus agreement remains subject to the terms of the stock bonus
agreement.

         (b) RESTRICTED STOCK AWARDS. Each restricted stock purchase agreement
shall be in such form and shall contain such terms and conditions as the Board
shall deem appropriate. The terms and conditions of the restricted stock
purchase agreements may change from time to time, and the terms and conditions
of separate restricted stock purchase agreements need not be identical, but each
restricted stock purchase agreement shall include (through incorporation of
provisions hereof by reference in the agreement or otherwise) the substance of
each of the following provisions:

                  (i) PURCHASE PRICE. The purchase price under each restricted
stock purchase agreement shall be such amount as the Board shall determine and
designate in such restricted stock purchase agreement. The purchase price shall
not be less than eighty-five percent (85%) of 


                                       9.

<PAGE>

the Common Stock's Fair Market Value on the date such award is made or at the
time the purchase is consummated.

                  (ii) CONSIDERATION. The purchase price of Common Stock
acquired pursuant to the restricted stock purchase agreement shall be paid
either: (i) in cash at the time of purchase; (ii) at the discretion of the
Board, according to a deferred payment or other similar arrangement with the
Participant; or (iii) in any other form of legal consideration that may be
acceptable to the Board in its discretion; provided, however, that at any time
that the Company is incorporated in Delaware, then payment of the Common Stock's
"par value," as defined in the Delaware General Corporation Law, shall not be
made by deferred payment.

                  (iii) VESTING. Shares of Common Stock acquired under the
restricted stock purchase agreement may, but need not, be subject to a share
repurchase option in favor of the Company in accordance with a vesting schedule
to be determined by the Board.

                  (iv) TERMINATION OF PARTICIPANT'S CONTINUOUS SERVICE. In the
event a Participant's Continuous Service terminates, the Company may repurchase
or otherwise reacquire any or all of the shares of Common Stock held by the
Participant which have not vested as of the date of termination under the terms
of the restricted stock purchase agreement.

                  (v) TRANSFERABILITY. Rights to acquire shares of Common Stock
under the restricted stock purchase agreement shall be transferable by the
Participant only upon such terms and conditions as are set forth in the
restricted stock purchase agreement, as the Board shall determine in its
discretion, so long as Common Stock awarded under the restricted stock purchase
agreement remains subject to the terms of the restricted stock purchase
agreement.

8.       COVENANTS OF THE COMPANY.

         (a) AVAILABILITY OF SHARES. During the terms of the Stock Awards, the
Company shall keep available at all times the number of shares of Common Stock
required to satisfy such Stock Awards.

         (b) SECURITIES LAW COMPLIANCE. The Company shall seek to obtain from
each regulatory commission or agency having jurisdiction over the Plan such
authority as may be required to grant Stock Awards and to issue and sell shares
of Common Stock upon exercise of the Stock Awards; provided, however, that this
undertaking shall not require the Company to register under the Securities Act
the Plan, any Stock Award or any Common Stock issued or issuable pursuant to any
such Stock Award. If, after reasonable efforts, the Company is unable to obtain
from any such regulatory commission or agency the authority which counsel for
the Company deems necessary for the lawful issuance and sale of Common Stock
under the Plan, the Company shall be relieved from any liability for failure to
issue and sell Common Stock upon exercise of such Stock Awards unless and until
such authority is obtained.

9.       USE OF PROCEEDS FROM STOCK.

         Proceeds from the sale of Common Stock pursuant to Stock Awards shall
constitute general funds of the Company.


                                      10.

<PAGE>

10.      MISCELLANEOUS.

         (a) ACCELERATION OF EXERCISABILITY AND VESTING. The Board shall have
the power to accelerate the time at which a Stock Award may first be exercised
or the time during which a Stock Award or any part thereof will vest in
accordance with the Plan, notwithstanding the provisions in the Stock Award
stating the time at which it may first be exercised or the time during which it
will vest.

         (b) STOCKHOLDER RIGHTS. No Participant shall be deemed to be the holder
of, or to have any of the rights of a holder with respect to, any shares of
Common Stock subject to such Stock Award unless and until such Participant has
satisfied all requirements for exercise of the Stock Award pursuant to its
terms.

         (c) NO EMPLOYMENT OR OTHER SERVICE RIGHTS. Nothing in the Plan or any
instrument executed or Stock Award granted pursuant thereto shall confer upon
any Participant any right to continue to serve the Company or an Affiliate in
the capacity in effect at the time the Stock Award was granted or shall affect
the right of the Company or an Affiliate to terminate (i) the employment of an
Employee with or without notice and with or without cause, (ii) the service of a
Consultant pursuant to the terms of such Consultant's agreement with the Company
or an Affiliate or (iii) the service of a Director pursuant to the Bylaws of the
Company or an Affiliate, and any applicable provisions of the corporate law of
the state in which the Company or the Affiliate is incorporated, as the case may
be.

         (d) INCENTIVE STOCK OPTION $100,000 LIMITATION. To the extent that the
aggregate Fair Market Value (determined at the time of grant) of Common Stock
with respect to which Incentive Stock Options are exercisable for the first time
by any Optionholder during any calendar year (under all plans of the Company and
its Affiliates) exceeds one hundred thousand dollars ($100,000), the Options or
portions thereof which exceed such limit (according to the order in which they
were granted) shall be treated as Nonstatutory Stock Options.

         (e) INVESTMENT ASSURANCES. The Company may require a Participant, as a
condition of exercising or acquiring Common Stock under any Stock Award, (i) to
give written assurances satisfactory to the Company as to the Participant's
knowledge and experience in financial and business matters and/or to employ a
purchaser representative reasonably satisfactory to the Company who is
knowledgeable and experienced in financial and business matters and that he or
she is capable of evaluating, alone or together with the purchaser
representative, the merits and risks of exercising the Stock Award; and (ii) to
give written assurances satisfactory to the Company stating that the Participant
is acquiring Common Stock subject to the Stock Award for the Participant's own
account and not with any present intention of selling or otherwise distributing
the Common Stock. The foregoing requirements, and any assurances given pursuant
to such requirements, shall be inoperative if (1) the issuance of the shares of
Common Stock upon the exercise or acquisition of Common Stock under the Stock
Award has been registered under a then currently effective registration
statement under the Securities Act or (2) as to any particular requirement, a
determination is made by counsel for the Company that such requirement need not
be met in the circumstances under the then applicable securities laws. The
Company may, upon advice of counsel to the Company, place legends on stock
certificates issued under the Plan as such counsel deems necessary or
appropriate in order to comply with 


                                      11.

<PAGE>

applicable securities laws, including, but not limited to, legends restricting
the transfer of the Common Stock.

         (f) WITHHOLDING OBLIGATIONS. To the extent provided by the terms of a
Stock Award Agreement, the Participant may satisfy any federal, state or local
tax withholding obligation relating to the exercise or acquisition of Common
Stock under a Stock Award by any of the following means (in addition to the
Company's right to withhold from any compensation paid to the Participant by the
Company) or by a combination of such means: (i) tendering a cash payment; (ii)
authorizing the Company to withhold shares of Common Stock from the shares of
Common Stock otherwise issuable to the Participant as a result of the exercise
or acquisition of Common Stock under the Stock Award, provided, however, that no
shares of Common Stock are withheld with a value exceeding the minimum amount of
tax required to be withheld by law; or (iii) delivering to the Company owned and
unencumbered shares of Common Stock.

11.      ADJUSTMENTS UPON CHANGES IN STOCK.

         (a) CAPITALIZATION ADJUSTMENTS. If any change is made in the Common
Stock subject to the Plan, or subject to any Stock Award, without the receipt of
consideration by the Company (through merger, consolidation, reorganization,
recapitalization, reincorporation, stock dividend, dividend in property other
than cash, stock split, liquidating dividend, combination of shares, exchange of
shares, change in corporate structure or other transaction not involving the
receipt of consideration by the Company), the Plan will be appropriately
adjusted in the class(es) and maximum number of securities subject to the Plan
pursuant to subsection 4(a) and the maximum number of securities subject to
award to any person pursuant to subsection 5(c), and the outstanding Stock
Awards will be appropriately adjusted in the class(es) and number of securities
and price per share of Common Stock subject to such outstanding Stock Awards.
The Board shall make such adjustments, and its determination shall be final,
binding and conclusive. (The conversion of any convertible securities of the
Company shall not be treated as a transaction "without receipt of consideration"
by the Company.)

         (b) DISSOLUTION OR LIQUIDATION. In the event of a dissolution or
liquidation of the Company, then all outstanding Stock Awards shall terminate
immediately prior to such event.

         (c) ASSET SALE, MERGER, CONSOLIDATION OR REVERSE MERGER. In the event
of (i) a sale, lease or other disposition of all or substantially all of the
assets of the Company, (ii) a merger or consolidation in which the Company is
not the surviving corporation or (iii) a reverse merger in which the Company is
the surviving corporation but the shares of Common Stock outstanding immediately
preceding the merger are converted by virtue of the merger into other property,
whether in the form of securities, cash or otherwise (individually, a "Corporate
Transaction"), then any surviving corporation or acquiring corporation shall
assume any Stock Awards outstanding under the Plan or shall substitute similar
stock awards (including an award to acquire the same consideration paid to the
stockholders in the Corporate Transaction for those outstanding under the Plan).
In the event any surviving corporation or acquiring corporation refuses to
assume such Stock Awards or to substitute similar stock awards for those
outstanding under the Plan, then with respect to Stock Awards held by
Participants whose Continuous Service has not terminated, the vesting of such
Stock Awards (and, if applicable, the time during which such Stock Awards may be
exercised) shall be accelerated in full, and the Stock Awards 


                                      12.

<PAGE>

shall terminate if not exercised (if applicable) at or prior to the Corporate
Transaction. With respect to any other Stock Awards outstanding under the Plan,
such Stock Awards shall terminate if not exercised (if applicable) prior to the
Corporate Transaction.

12.      AMENDMENT OF THE PLAN AND STOCK AWARDS.

         (a) AMENDMENT OF PLAN. The Board at any time, and from time to time,
may amend the Plan. However, except as provided in Section 11 relating to
adjustments upon changes in Common Stock, no amendment shall be effective unless
approved by the stockholders of the Company to the extent stockholder approval
is necessary to satisfy the requirements of Section 422 of the Code, Rule 16b-3
or any Nasdaq or securities exchange listing requirements.

         (b) STOCKHOLDER APPROVAL. The Board may, in its sole discretion, submit
any other amendment to the Plan for stockholder approval, including, but not
limited to, amendments to the Plan intended to satisfy the requirements of
Section 162(m) of the Code and the regulations thereunder regarding the
exclusion of performance-based compensation from the limit on corporate
deductibility of compensation paid to certain executive officers.

         (c) CONTEMPLATED AMENDMENTS. It is expressly contemplated that the
Board may amend the Plan in any respect the Board deems necessary or advisable
to provide eligible Employees with the maximum benefits provided or to be
provided under the provisions of the Code and the regulations promulgated
thereunder relating to Incentive Stock Options and/or to bring the Plan and/or
Incentive Stock Options granted under it into compliance therewith.

         (d) NO IMPAIRMENT OF RIGHTS. Rights under any Stock Award granted
before amendment of the Plan shall not be impaired by any amendment of the Plan
unless (i) the Company requests the consent of the Participant and (ii) the
Participant consents in writing.

         (e) AMENDMENT OF STOCK AWARDS. The Board at any time, and from time to
time, may amend the terms of any one or more Stock Awards; provided, however,
that the rights under any Stock Award shall not be impaired by any such
amendment unless (i) the Company requests the consent of the Participant and
(ii) the Participant consents in writing.

13.      TERMINATION OR SUSPENSION OF THE PLAN.

         (a) PLAN TERM. The Board may suspend or terminate the Plan at any time.
Unless sooner terminated, the Plan shall terminate on the day before the tenth
(10th) anniversary of the date the Plan is adopted by the Board or approved by
the stockholders of the Company, whichever is earlier. No Stock Awards may be
granted under the Plan while the Plan is suspended or after it is terminated.

         (b) NO IMPAIRMENT OF RIGHTS. Suspension or termination of the Plan
shall not impair rights and obligations under any Stock Award granted while the
Plan is in effect except with the written consent of the Participant.


                                      13.

<PAGE>

14.      EFFECTIVE DATE OF PLAN.

         The Plan shall become effective as determined by the Board, but no
Stock Award shall be exercised (or, in the case of a stock bonus, shall be
granted) unless and until the Plan has been approved by the stockholders of the
Company, which approval shall be within twelve (12) months before or after the
date the Plan is adopted by the Board.

15.      CHOICE OF LAW.

         The law of the State of California shall govern all questions
concerning the construction, validity and interpretation of this Plan, without
regard to such state's conflict of laws rules.
















                                      14.

<PAGE>

                           ACADIA PHARMACEUTICALS INC.
                            STOCK OPTION GRANT NOTICE
                          (2000 EQUITY INCENTIVE PLAN)


ACADIA PHARMACEUTICALS INC. (the "Company"), pursuant to its 2000 Equity
Incentive Plan (the "Plan"), hereby grants to Optionholder an option to purchase
the number of shares of the Company's Common Stock set forth below. This option
is subject to all of the terms and conditions as set forth herein and in the
Stock Option Agreement, the Plan and the Notice of Exercise, all of which are
attached hereto and incorporated herein in their entirety.

Optionholder:                           _______________________________________
Date of Grant:                          _______________________________________
Vesting Commencement Date:              _______________________________________
Number of Shares Subject to Option:     _______________________________________
Exercise Price (Per Share):             _______________________________________
Total Exercise Price:                   _______________________________________
Expiration Date:                        _______________________________________


TYPE OF GRANT:     / /  Incentive Stock Option(1) / /  Nonstatutory Stock Option

EXERCISE SCHEDULE: [Same as Vesting Schedule] [Early Exercise Permitted]

VESTING SCHEDULE:  [1/4th  of the shares vest one year after the Vesting 
                   Commencement Date. 
                   1/48th of the shares vest monthly thereafter over the 
                   next three years.]

PAYMENT:           By one or a combination of the following items (described in
                   the Stock Option Agreement):

                            By cash or check
                            Pursuant to a Regulation T Program if the Shares
                            are publicly traded 
                            By delivery of already-owned shares if the Shares 
                            are publicly traded 
                            [By deferred payment]

ADDITIONAL TERMS/ACKNOWLEDGEMENTS: The undersigned Optionholder acknowledges
receipt of, and understands and agrees to, this Grant Notice, the Stock Option
Agreement and the Plan. Optionholder further acknowledges that as of the Date of
Grant, this Grant Notice, the Stock Option Agreement and the Plan set forth the
entire understanding between Optionholder and the Company regarding the
acquisition of stock in the Company and supersede all prior oral and written
agreements on that subject with the exception of (i) options previously granted
and delivered to Optionholder under the Plan, and (ii) the following agreements
only:

         OTHER AGREEMENTS:              _______________________________________
                                        _______________________________________

ACADIA PHARMACEUTICALS INC.                 OPTIONHOLDER:

By:______________________________________   ___________________________________
                  Signature                                  Signature

Title:___________________________________   Date:______________________________


Date:____________________________________

ATTACHMENTS: Stock Option Agreement, 2000 Equity Incentive Plan and Notice of
Exercise



_________________________

(1) If this is an incentive stock option, it (plus your other outstanding
incentive stock options) cannot be first EXERCISABLE for more than $100,000 in
any calendar year. Any excess over $100,000 is a nonstatutory stock option.


<PAGE>

                           ACADIA PHARMACEUTICALS INC.
                           2000 EQUITY INCENTIVE PLAN

                             STOCK OPTION AGREEMENT
              (INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK OPTION)


         Pursuant to your Stock Option Grant Notice ("Grant Notice") and this
Stock Option Agreement, ACADIA Pharmaceuticals Inc. (the "Company") has granted
you an option under its 2000 Equity Incentive Plan (the "Plan") to purchase the
number of shares of the Company's Common Stock indicated in your Grant Notice at
the exercise price indicated in your Grant Notice. Defined terms not explicitly
defined in this Stock Option Agreement but defined in the Plan shall have the
same definitions as in the Plan.

         The details of your option are as follows:

         1. VESTING. Subject to the limitations contained herein, your option
will vest as provided in your Grant Notice, provided that vesting will cease
upon the termination of your Continuous Service.

         2. NUMBER OF SHARES AND EXERCISE PRICE. The number of shares of Common
Stock subject to your option and your exercise price per share referenced in
your Grant Notice may be adjusted from time to time for Capitalization
Adjustments, as provided in the Plan.

         3. EXERCISE PRIOR TO VESTING ("EARLY EXERCISE"). If permitted in your
Grant Notice (i.e., the "Exercise Schedule" indicates that "Early Exercise" of
your option is permitted) and subject to the provisions of your option, you may
elect at any time that is both (i) during the period of your Continuous Service
and (ii) during the term of your option, to exercise all or part of your option,
including the nonvested portion of your option; provided, however, that:

                  (a) a partial exercise of your option shall be deemed to cover
first vested shares of Common Stock and then the earliest vesting installment of
unvested shares of Common Stock;

                  (b) any shares of Common Stock so purchased from installments
that have not vested as of the date of exercise shall be subject to the purchase
option in favor of the Company as described in the Company's form of Early
Exercise Stock Purchase Agreement;

                  (c) you shall enter into the Company's form of Early Exercise
Stock Purchase Agreement with a vesting schedule that will result in the same
vesting as if no early exercise had occurred; and

                  (d) if your option is an incentive stock option, then, as
provided in the Plan, to the extent that the aggregate Fair Market Value
(determined at the time of grant) of the shares of Common Stock with respect to
which your option plus all other incentive stock options you hold are
exercisable for the first time by you during any calendar year (under all plans
of the Company and its Affiliates) exceeds one hundred thousand dollars
($100,000), your option(s) or 


                                       1.

<PAGE>

portions thereof that exceed such limit (according to the order in which they
were granted) shall be treated as nonstatutory stock options.

         4. METHOD OF PAYMENT. Payment of the exercise price is due in full upon
exercise of all or any part of your option. You may elect to make payment of the
exercise price in cash or by check or in any other manner PERMITTED BY YOUR
GRANT NOTICE, which may include one or more of the following:

                  (a) In the Company's sole discretion at the time your option
is exercised and provided that at the time of exercise the Common Stock is
publicly traded and quoted regularly in THE WALL STREET JOURNAL, pursuant to a
program developed under Regulation T as promulgated by the Federal Reserve Board
that, prior to the issuance of Common Stock, results in either the receipt of
cash (or check) by the Company or the receipt of irrevocable instructions to pay
the aggregate exercise price to the Company from the sales proceeds.

                  (b) Provided that at the time of exercise the Common Stock is
publicly traded and quoted regularly in THE WALL STREET JOURNAL, by delivery of
already-owned shares of Common Stock either that you have held for the period
required to avoid a charge to the Company's reported earnings (generally six
months) or that you did not acquire, directly or indirectly from the Company,
that are owned free and clear of any liens, claims, encumbrances or security
interests, and that are valued at Fair Market Value on the date of exercise.
"Delivery" for these purposes, in the sole discretion of the Company at the time
you exercise your option, shall include delivery to the Company of your
attestation of ownership of such shares of Common Stock in a form approved by
the Company. Notwithstanding the foregoing, you may not exercise your option by
tender to the Company of Common Stock to the extent such tender would violate
the provisions of any law, regulation or agreement restricting the redemption of
the Company's stock.

                  (c) Pursuant to the following deferred payment alternative:

                           (i) Not less than one hundred percent (100%) of the
aggregate exercise price, plus accrued interest, shall be due four (4) years
from date of exercise or, at the Company's election, upon termination of your
Continuous Service.

                           (ii) Interest shall be compounded at least annually
and shall be charged at the market rate of interest necessary to avoid a charge
to earnings for financial accounting purposes.

                           (iii) At any time that the Company is incorporated in
Delaware, payment of the Common Stock's "par value," as defined in the Delaware
General Corporation Law, shall be made in cash and not by deferred payment.

                           (iv) In order to elect the deferred payment
alternative, you must, as a part of your written notice of exercise, give notice
of the election of this payment alternative and, in order to secure the payment
of the deferred exercise price to the Company hereunder, if the Company so
requests, you must tender to the Company a promissory note and a security
agreement covering the purchased shares of Common Stock, both in form and
substance 


                                       2.

<PAGE>

satisfactory to the Company, or such other or additional documentation as the
Company may request.

         5. WHOLE SHARES. You may exercise your option only for whole shares of
Common Stock.

         6. SECURITIES LAW COMPLIANCE. Notwithstanding anything to the contrary
contained herein, you may not exercise your option unless the shares of Common
Stock issuable upon such exercise are then registered under the Securities Act
or, if such shares of Common Stock are not then so registered, the Company has
determined that such exercise and issuance would be exempt from the registration
requirements of the Securities Act. The exercise of your option must also comply
with other applicable laws and regulations governing your option, and you may
not exercise your option if the Company determines that such exercise would not
be in material compliance with such laws and regulations.

         7. TERM. You may not exercise your option before the commencement of
its term or after its term expires. The term of your option commences on the
Date of Grant and expires upon the EARLIEST of the following:

                  (a) three (3) months after the termination of your Continuous
Service for any reason other than your Disability or death, provided that if
during any part of such three- (3-) month period your option is not exercisable
solely because of the condition set forth in the preceding paragraph relating to
"Securities Law Compliance," your option shall not expire until the earlier of
the Expiration Date or until it shall have been exercisable for an aggregate
period of three (3) months after the termination of your Continuous Service;

                  (b) twelve (12) months after the termination of your
Continuous Service due to your Disability;

                  (c) eighteen (18) months after your death if you die either
during your Continuous Service or within three (3) months after your Continuous
Service terminates;

                  (d) the Expiration Date indicated in your Grant Notice; or

                  (e) the day before the tenth (10th) anniversary of the Date of
Grant.

         If your option is an incentive stock option, note that, to obtain the
federal income tax advantages associated with an "incentive stock option," the
Code requires that at all times beginning on the date of grant of your option
and ending on the day three (3) months before the date of your option's
exercise, you must be an employee of the Company or an Affiliate, except in the
event of your death or Disability. The Company has provided for extended
exercisability of your option under certain circumstances for your benefit but
cannot guarantee that your option will necessarily be treated as an "incentive
stock option" if you continue to provide services to the Company or an Affiliate
as a Consultant or Director after your employment terminates or if you otherwise
exercise your option more than three (3) months after the date your employment
terminates.


                                       3.

<PAGE>

         8.       EXERCISE.

                  (a) You may exercise the vested portion of your option (and
the unvested portion of your option if your Grant Notice so permits) during its
term by delivering a Notice of Exercise (in a form designated by the Company)
together with the exercise price to the Secretary of the Company, or to such
other person as the Company may designate, during regular business hours,
together with such additional documents as the Company may then require.

                  (b) By exercising your option you agree that, as a condition
to any exercise of your option, the Company may require you to enter into an
arrangement providing for the payment by you to the Company of any tax
withholding obligation of the Company arising by reason of (1) the exercise of
your option, (2) the lapse of any substantial risk of forfeiture to which the
shares of Common Stock are subject at the time of exercise, or (3) the
disposition of shares of Common Stock acquired upon such exercise.

                  (c) If your option is an incentive stock option, by exercising
your option you agree that you will notify the Company in writing within fifteen
(15) days after the date of any disposition of any of the shares of the Common
Stock issued upon exercise of your option that occurs within two (2) years after
the date of your option grant or within one (1) year after such shares of Common
Stock are transferred upon exercise of your option.

         9. TRANSFERABILITY. Your option is not transferable, except by will or
by the laws of descent and distribution, and is exercisable during your life
only by you. Notwithstanding the foregoing, by delivering written notice to the
Company, in a form satisfactory to the Company, you may designate a third party
who, in the event of your death, shall thereafter be entitled to exercise your
option.

         10. OPTION NOT A SERVICE CONTRACT. Your option is not an employment or
service contract, and nothing in your option shall be deemed to create in any
way whatsoever any obligation on your part to continue in the employ of the
Company or an Affiliate, or of the Company or an Affiliate to continue your
employment. In addition, nothing in your option shall obligate the Company or an
Affiliate, their respective stockholders, Boards of Directors, Officers or
Employees to continue any relationship that you might have as a Director or
Consultant for the Company or an Affiliate.

         11. WITHHOLDING OBLIGATIONS.

                  (a) At the time you exercise your option, in whole or in part,
or at any time thereafter as requested by the Company, you hereby authorize
withholding from payroll and any other amounts payable to you, and otherwise
agree to make adequate provision for (including by means of a "cashless
exercise" pursuant to a program developed under Regulation T as promulgated by
the Federal Reserve Board to the extent permitted by the Company), any sums
required to satisfy the federal, state, local and foreign tax withholding
obligations of the Company or an Affiliate, if any, which arise in connection
with your option.

                  (b) Upon your request and subject to approval by the Company,
in its sole discretion, and compliance with any applicable conditions or
restrictions of law, the Company may withhold from fully vested shares of Common
Stock otherwise issuable to you upon the 


                                       4.

<PAGE>

exercise of your option a number of whole shares of Common Stock having a Fair
Market Value, determined by the Company as of the date of exercise, not in
excess of the minimum amount of tax required to be withheld by law. If the date
of determination of any tax withholding obligation is deferred to a date later
than the date of exercise of your option, share withholding pursuant to the
preceding sentence shall not be permitted unless you make a proper and timely
election under Section 83(b) of the Code, covering the aggregate number of
shares of Common Stock acquired upon such exercise with respect to which such
determination is otherwise deferred, to accelerate the determination of such tax
withholding obligation to the date of exercise of your option. Notwithstanding
the filing of such election, shares of Common Stock shall be withheld solely
from fully vested shares of Common Stock determined as of the date of exercise
of your option that are otherwise issuable to you upon such exercise. Any
adverse consequences to you arising in connection with such share withholding
procedure shall be your sole responsibility.

                  (c) You may not exercise your option unless the tax
withholding obligations of the Company and/or any Affiliate are satisfied.
Accordingly, you may not be able to exercise your option when desired even
though your option is vested, and the Company shall have no obligation to issue
a certificate for such shares of Common Stock or release such shares of Common
Stock from any escrow provided for herein.

         12. NOTICES. Any notices provided for in your option or the Plan shall
be given in writing and shall be deemed effectively given upon receipt or, in
the case of notices delivered by mail by the Company to you, five (5) days after
deposit in the United States mail, postage prepaid, addressed to you at the last
address you provided to the Company.

         13. GOVERNING PLAN DOCUMENT. Your option is subject to all the
provisions of the Plan, the provisions of which are hereby made a part of your
option, and is further subject to all interpretations, amendments, rules and
regulations which may from time to time be promulgated and adopted pursuant to
the Plan. In the event of any conflict between the provisions of your option and
those of the Plan, the provisions of the Plan shall control.


                                       5.


<PAGE>

                               NOTICE OF EXERCISE


ACADIA Pharmaceuticals Inc.
3911 Sorrento Valley Blvd.
San Diego, CA 92121                                Date of Exercise: ___________

Ladies and Gentlemen:

         This constitutes notice under my stock option that I elect to purchase
the number of shares for the price set forth below.

         Type of option (check one):           Incentive / /   Nonstatutory / /

         Stock option dated:                   _______________

         Number of shares as
         to which option is
         exercised:                            _______________

         Certificates to be
         issued in name of:                    _______________

         Total exercise price:                 $______________

         Cash payment delivered
         herewith:                             $______________

         [Promissory note delivered
         herewith:                             $______________]

         Value of ________ shares of ACADIA 
         Pharmaceuticals Inc.
         common stock delivered herewith(1):   $______________

         By this exercise, I agree (i) to provide such additional documents as
you may require pursuant to the terms of the ACADIA Pharmaceuticals, Inc. 2000
Equity Incentive Plan, (ii) to provide for the payment by me to you (in the
manner designated by you) of your withholding obligation, if any, relating to
the exercise of this option, and (iii) if this exercise relates to an incentive
stock option, to notify you in writing within fifteen (15) days after the date
of any disposition of any of the shares of Common Stock issued upon exercise of
this option that occurs within two (2) years after the date of grant of this
option or within one (1) year after such shares of Common Stock are issued upon
exercise of this option.

                                               Very truly yours,



                                               ________________________________




_______________________________

(1)      Shares must meet the public trading requirements set forth in the
option. Shares must be valued in accordance with the terms of the option being
exercised, must have been owned for the minimum period required in the option,
and must be owned free and clear of any liens, claims, encumbrances or security
interests. Certificates must be endorsed or accompanied by an executed
assignment separate from certificate.



<PAGE>

                           ACADIA PHARMACEUTICALS INC.

                 2000 NON-EMPLOYEE DIRECTORS' STOCK OPTION PLAN

                            ADOPTED DECEMBER 20, 2000
                  APPROVED BY STOCKHOLDERS ____________, 200__
                     EFFECTIVE DATE: _______________, 200__


1.       PURPOSES.

         (a) ELIGIBLE OPTION RECIPIENTS. The persons eligible to receive Options
are the Non-Employee Directors of the Company.

         (b) AVAILABLE OPTIONS. The purpose of the Plan is to provide a means by
which Non-Employee Directors may be given an opportunity to benefit from
increases in value of the Common Stock through the granting of Nonstatutory
Stock Options.

         (c) GENERAL PURPOSE. The Company, by means of the Plan, seeks to retain
the services of its Non-Employee Directors, to secure and retain the services of
new Non-Employee Directors and to provide incentives for such persons to exert
maximum efforts for the success of the Company and its Affiliates.

2.       DEFINITIONS.

         (a) "AFFILIATE" means any parent corporation or subsidiary corporation
of the Company, whether now or hereafter existing, as those terms are defined in
Sections 424(e) and (f), respectively, of the Code.

         (b) "ANNUAL GRANT" means an Option granted annually to all Non-Employee
Directors who meet the criteria specified in subsection 6(b) of the Plan.

         (c) "ANNUAL MEETING" means the annual meeting of the stockholders
 of
the Company.

         (d) "BOARD" means the Board of Directors of the Company.

         (e) "CODE" means the Internal Revenue Code of 1986, as amended.

         (f) "COMMON STOCK" means the common stock of the Company.

         (g) "COMPANY" means ACADIA Pharmaceuticals Inc., a Delaware
corporation.

         (h) "CONSULTANT" means any person, including an advisor, (i) engaged by
the Company or an Affiliate to render consulting or advisory services and who is
compensated for such services or (ii) who is a member of the Board of Directors
of an Affiliate. However, the term "Consultant" shall not include either
Directors of the Company who are not compensated 


                                       1.

<PAGE>

by the Company for their services as Directors or Directors of the Company who
are merely paid a director's fee by the Company for their services as Directors.

         (i) "CONTINUOUS SERVICE" means that the Optionholder's service with the
Company or an Affiliate, whether as an Employee, Director or Consultant, is not
interrupted or terminated. The Optionholder's Continuous Service shall not be
deemed to have terminated merely because of a change in the capacity in which
the Optionholder renders service to the Company or an Affiliate as an Employee,
Consultant or Director or a change in the entity for which the Optionholder
renders such service, provided that there is no interruption or termination of
the Optionholder's service. For example, a change in status without interruption
from a Non-Employee Director of the Company to a Consultant of an Affiliate or
an Employee of the Company will not constitute an interruption of Continuous
Service. The Board or the chief executive officer of the Company, in that
party's sole discretion, may determine whether Continuous Service shall be
considered interrupted in the case of any leave of absence approved by that
party, including sick leave, military leave or any other personal leave.

         (j) "DIRECTOR" means a member of the Board of Directors of the Company.

         (k) "DISABILITY" means the permanent and total disability of a person
within the meaning of Section 22(e)(3) of the Code.

         (l) "EMPLOYEE" means any person employed by the Company or an
Affiliate. Mere service as a Director or payment of a director's fee by the
Company or an Affiliate shall not be sufficient to constitute "employment" by
the Company or an Affiliate.

         (m) "EXCHANGE ACT" means the Securities Exchange Act of 1934, as
amended.

         (n) "FAIR MARKET VALUE" means, as of any date, the value of the Common
Stock determined as follows:

                  (i) If the Common Stock is listed on any established stock
exchange or traded on the Nasdaq National Market or the Nasdaq SmallCap Market,
the Fair Market Value of a share of Common Stock shall be the closing sales
price for such stock (or the closing bid, if no sales were reported) as quoted
on such exchange or market (or the exchange or market with the greatest volume
of trading in the Common Stock) on the last market trading day prior to the day
of determination, as reported in The Wall Street Journal or such other source as
the Board deems reliable.

                  (ii) In the absence of such markets for the Common Stock, the
Fair Market Value shall be determined in good faith by the Board.

         (o) "INITIAL GRANT" means an Option granted to a Non-Employee Director
who meets the criteria specified in subsection 6(a) of the Plan.

         (p) "IPO DATE" means the effective date of the initial public offering
of the Common Stock.

         (q) "NON-EMPLOYEE DIRECTOR" means a Director who is not an Employee.


                                       2.

<PAGE>

         (r) "NONSTATUTORY STOCK OPTION" means an Option not intended to qualify
as an incentive stock option within the meaning of Section 422 of the Code and
the regulations promulgated thereunder.

         (s) "OFFICER" means a person who is an officer of the Company within
the meaning of Section 16 of the Exchange Act and the rules and regulations
promulgated thereunder.

         (t) "OPTION" means a Nonstatutory Stock Option granted pursuant to the
Plan.

         (u) "OPTION AGREEMENT" means a written agreement between the Company
and an Optionholder evidencing the terms and conditions of an individual Option
grant. Each Option Agreement shall be subject to the terms and conditions of the
Plan.

         (v) "OPTIONHOLDER" means a person to whom an Option is granted pursuant
to the Plan or, if applicable, such other person who holds an outstanding
Option.

         (w) "PLAN" means this ACADIA Pharmaceuticals Inc. 2000 Non-Employee
Directors' Stock Option Plan.

         (x) "RULE 16b-3" means Rule 16b-3 promulgated under the Exchange Act or
any successor to Rule 16b-3, as in effect from time to time.

         (y) "SECURITIES ACT" means the Securities Act of 1933, as amended.

3.       ADMINISTRATION.

         (a) ADMINISTRATION BY BOARD. The Board shall administer the Plan. The
Board may not delegate administration of the Plan to a committee.

         (b) POWERS OF BOARD. The Board shall have the power, subject to, and
within the limitations of, the express provisions of the Plan:

                  (i) To determine the provisions of each Option to the extent
not specified in the Plan.

                  (ii) To construe and interpret the Plan and Options granted
under it, and to establish, amend and revoke rules and regulations for its
administration. The Board, in the exercise of this power, may correct any
defect, omission or inconsistency in the Plan or in any Option Agreement, in a
manner and to the extent it shall deem necessary or expedient to make the Plan
fully effective.

                  (iii) To amend the Plan or an Option as provided in 
Section 12.

                  (iv) To terminate or suspend the Plan as provided in 
Section 13.

                  (v) Generally, to exercise such powers and to perform such
acts as the Board deems necessary or expedient to promote the best interests of
the Company that are not in conflict with the provisions of the Plan.


                                       3.

<PAGE>

         (c) EFFECT OF BOARD'S DECISION. All determinations, interpretations and
constructions made by the Board in good faith shall not be subject to review by
any person and shall be final, binding and conclusive on all persons.

4.       SHARES SUBJECT TO THE PLAN.

         (a) SHARE RESERVE. Subject to the provisions of Section 11 relating to
adjustments, the Common Stock that may be issued pursuant to Options shall not
exceed two hundred thousand (200,000) shares of Common Stock.

         (b) REVERSION OF SHARES TO THE SHARE RESERVE. If any Option shall for
any reason expire or otherwise terminate, in whole or in part, without having
been exercised in full, the shares of Common Stock not acquired under such
Option shall revert to and again become available for issuance under the Plan.

         (c) SOURCE OF SHARES. The shares of Common Stock subject to the Plan
may be unissued shares or reacquired shares, bought on the market or otherwise.

5.       ELIGIBILITY.

         The Options as set forth in Section 6 of the Plan automatically shall
be granted under the Plan to all Non-Employee Directors.

6.       NON-DISCRETIONARY GRANTS.

         (a) INITIAL GRANTS. Without any further action of the Board, each
person who is elected or appointed for the first time to be a Non-Employee
Director after the IPO Date automatically shall, upon the date of his or her
initial election or appointment to be a Non-Employee Director by the Board or
stockholders of the Company, be granted an Initial Grant to purchase Twelve
Thousand (12,000) shares of Common Stock on the terms and conditions set forth
herein.

         (b) ANNUAL GRANTS. Without any further action of the Board, a
Non-Employee Director shall be granted an Annual Grant as follows: On the day
following each Annual Meeting commencing with the Annual Meeting in 2002, each
person who is then a Non-Employee Director automatically shall be granted an
Annual Grant to purchase Three Thousand (3,000) shares of Common Stock on the
terms and conditions set forth herein; PROVIDED, HOWEVER, that if the person has
not been serving as a Non-Employee Director for the entire twelve (12) month
period since the preceding Annual Meeting, then the number of shares subject to
the Annual Grant shall be reduced pro rata for each full month prior to the date
of grant during which such person did not serve as a Non-Employee Director.

7.       OPTION PROVISIONS.

         Each Option shall be in such form and shall contain such terms and
conditions as required by the Plan. Each Option shall contain such additional
terms and conditions, not inconsistent with the Plan, as the Board shall deem
appropriate. Each Option shall include 


                                       4.

<PAGE>

(through incorporation of provisions hereof by reference in the Option or
otherwise) the substance of each of the following provisions:

         (a) TERM. No Option shall be exercisable after the expiration of ten
(10) years from the date it was granted.

         (b) EXERCISE PRICE. The exercise price of each Option shall be one
hundred percent (100%) of the Fair Market Value of the stock subject to the
Option on the date the Option is granted. Notwithstanding the foregoing, an
Option may be granted with an exercise price lower than that set forth in the
preceding sentence if such Option is granted pursuant to an assumption or
substitution for another option in a manner satisfying the provisions of Section
424(a) of the Code.

         (c) CONSIDERATION. The purchase price of stock acquired pursuant to an
Option may be paid, to the extent permitted by applicable statutes and
regulations, in any combination of the following methods:

                  (i) By cash or check.

                  (ii) Provided that at the time of exercise the Common Stock is
publicly traded and quoted regularly in THE WALL STREET JOURNAL, by delivery of
already-owned shares of Common Stock either that the Optionholder has held for
the period required to avoid a charge to the Company's reported earnings
(generally six months) or that the Optionholder did not acquire, directly or
indirectly from the Company, that are owned free and clear of any liens, claims,
encumbrances or security interests, and that are valued at Fair Market Value on
the date of exercise. "Delivery" for these purposes shall include delivery to
the Company of the Optionholder's attestation of ownership of such shares of
Common Stock in a form approved by the Company. Notwithstanding the foregoing,
the Optionholder may not exercise the Option by tender to the Company of Common
Stock to the extent such tender would violate the provisions of any law,
regulation or agreement restricting the redemption of the Company's stock.

                  (iii) Provided that at the time of exercise the Common Stock
is publicly traded and quoted regularly in THE WALL STREET JOURNAL, pursuant to
a program developed under Regulation T as promulgated by the Federal Reserve
Board that, prior to the issuance of Common Stock, results in either the receipt
of cash (or check) by the Company or the receipt of irrevocable instructions to
pay the aggregate exercise price to the Company from the sales proceeds.

         (d) TRANSFERABILITY. An Option is transferable by will or by the laws
of descent and distribution. An Option also is transferable (i) by instrument to
an inter vivos or testamentary trust, in a form accepted by the Company, in
which the Option is to be passed to beneficiaries upon the death of the trustor
(settlor) and (ii) by gift, in a form accepted by the Company, to a member of
the "immediate family" of the Optionholder as that term is defined in 17 C.F.R.
240.16a-1(e). An Option shall be exercisable during the lifetime of the
Optionholder only by the Optionholder and a permitted transferee as provided
herein. However, the Optionholder may, by delivering written notice to the
Company, in a form satisfactory to the Company, designate a 


                                       5.

<PAGE>

third party who, in the event of the death of the Optionholder, shall thereafter
be entitled to exercise the Option.

         (e) EXERCISE SCHEDULE. The Option shall be exercisable as the shares of
Common Stock subject to the Option vest.

         (f) VESTING GENERALLY. Options shall vest and become exercisable as
follows:

                  (i) Initial Grants shall provide for one year cliff vesting of
1/3rd of the shares from the date of grant with 1/12th vesting every three
months thereafter.

                  (ii) Annual Grants shall provide for vesting of 1/4th of the
shares every three months after the date of the grant.

         (g) TERMINATION OF CONTINUOUS SERVICE. In the event an Optionholder's
Continuous Service terminates (other than upon the Optionholder's death or
Disability), the Optionholder may exercise his or her Option (to the extent that
the Optionholder was entitled to exercise it as of the date of termination) but
only within such period of time ending on the earlier of (i) the date three (3)
months following the termination of the Optionholder's Continuous Service, or
(ii) the expiration of the term of the Option as set forth in the Option
Agreement. If, after termination, the Optionholder does not exercise his or her
Option within the time specified in the Option Agreement, the Option shall
terminate.

         (h) EXTENSION OF TERMINATION DATE. If the exercise of the Option
following the termination of the Optionholder's Continuous Service (other than
upon the Optionholder's death or Disability) would be prohibited at any time
solely because the issuance of shares would violate the registration
requirements under the Securities Act, then the Option shall terminate on the
earlier of (i) the expiration of the term of the Option set forth in subsection
7(a) or (ii) the expiration of a period of three (3) months after the
termination of the Optionholder's Continuous Service during which the exercise
of the Option would not be in violation of such registration requirements.

         (i) DISABILITY OF OPTIONHOLDER. In the event an Optionholder's
Continuous Service terminates as a result of the Optionholder's Disability, the
Optionholder may exercise his or her Option (to the extent that the Optionholder
was entitled to exercise it as of the date of termination), but only within such
period of time ending on the earlier of (i) the date twelve (12) months
following such termination or (ii) the expiration of the term of the Option as
set forth in the Option Agreement. If, after termination, the Optionholder does
not exercise his or her Option within the time specified herein, the Option
shall terminate.

         (j) DEATH OF OPTIONHOLDER. In the event (i) an Optionholder's
Continuous Service terminates as a result of the Optionholder's death or (ii)
the Optionholder dies within the three-month period after the termination of the
Optionholder's Continuous Service for a reason other than death, then the Option
may be exercised (to the extent the Optionholder was entitled to exercise the
Option as of the date of death) by the Optionholder's estate, by a person who
acquired the right to exercise the Option by bequest or inheritance or by a
person designated to exercise the Option upon the Optionholder's death, but only
within the period ending on the earlier of (1) the date eighteen (18) months
following the date of death or (2) the expiration of  


                                       6.

<PAGE>

the term of such Option as set forth in the Option Agreement. If, after death, 
the Option is not exercised within the time specified herein, the Option shall
terminate.

8.       COVENANTS OF THE COMPANY.

         (a) AVAILABILITY OF SHARES. During the terms of the Options, the
Company shall keep available at all times the number of shares of Common Stock
required to satisfy such Options.

         (b) SECURITIES LAW COMPLIANCE. The Company shall seek to obtain from
each regulatory commission or agency having jurisdiction over the Plan such
authority as may be required to grant Options and to issue and sell shares of
Common Stock upon exercise of the Options; provided, however, that this
undertaking shall not require the Company to register under the Securities Act
the Plan, any Option or any stock issued or issuable pursuant to any such
Option. If, after reasonable efforts, the Company is unable to obtain from any
such regulatory commission or agency the authority which counsel for the Company
deems necessary for the lawful issuance and sale of stock under the Plan, the
Company shall be relieved from any liability for failure to issue and sell stock
upon exercise of such Options unless and until such authority is obtained.

9.       USE OF PROCEEDS FROM STOCK.

         Proceeds from the sale of stock pursuant to Options shall constitute
general funds of the Company.

10.      MISCELLANEOUS.

         (a) STOCKHOLDER RIGHTS. No Optionholder shall be deemed to be the
holder of, or to have any of the rights of a holder with respect to, any shares
subject to such Option unless and until such Optionholder has satisfied all
requirements for exercise of the Option pursuant to its terms.

         (b) NO SERVICE RIGHTS. Nothing in the Plan or any instrument executed
or Option granted pursuant thereto shall confer upon any Optionholder any right
to continue to serve the Company as a Non-Employee Director or shall affect the
right of the Company or an Affiliate to terminate (i) the employment of an
Employee with or without notice and with or without cause, (ii) the service of a
Consultant pursuant to the terms of such Consultant's agreement with the Company
or an Affiliate or (iii) the service of a Director pursuant to the Bylaws of the
Company or an Affiliate, and any applicable provisions of the corporate law of
the state in which the Company or the Affiliate is incorporated, as the case may
be.

         (c) INVESTMENT ASSURANCES. The Company may require an Optionholder, as
a condition of exercising or acquiring stock under any Option, (i) to give
written assurances satisfactory to the Company as to the Optionholder's
knowledge and experience in financial and business matters and/or to employ a
purchaser representative reasonably satisfactory to the Company who is
knowledgeable and experienced in financial and business matters and that he or
she is capable of evaluating, alone or together with the purchaser
representative, the merits and risks of exercising the Option; and (ii) to give
written assurances satisfactory to the Company stating that the Optionholder is
acquiring the stock subject to the Option for the Optionholder's 


                                       7.

<PAGE>

own account and not with any present intention of selling or otherwise
distributing the stock. The foregoing requirements, and any assurances given
pursuant to such requirements, shall be inoperative if (1) the issuance of the
shares upon the exercise or acquisition of stock under the Option has been
registered under a then currently effective registration statement under the
Securities Act or (2) as to any particular requirement, a determination is made
by counsel for the Company that such requirement need not be met in the
circumstances under the then applicable securities laws. The Company may, upon
advice of counsel to the Company, place legends on stock certificates issued
under the Plan as such counsel deems necessary or appropriate in order to comply
with applicable securities laws, including, but not limited to, legends
restricting the transfer of the stock.

         (d) WITHHOLDING OBLIGATIONS. The Optionholder may satisfy any federal,
state or local tax withholding obligation relating to the exercise or
acquisition of stock under an Option by any of the following means (in addition
to the Company's right to withhold from any compensation paid to the
Optionholder by the Company) or by a combination of such means: (i) tendering a
cash payment; (ii) authorizing the Company to withhold shares from the shares of
the Common Stock otherwise issuable to the Optionholder as a result of the
exercise or acquisition of stock under the Option, provided, however, that no
shares of Common Stock are withheld with a value exceeding the minimum amount of
tax required to be withheld by law; or (iii) delivering to the Company owned and
unencumbered shares of the Common Stock.

11.      ADJUSTMENTS UPON CHANGES IN STOCK.

         (a) CAPITALIZATION ADJUSTMENTS. If any change is made in the stock
subject to the Plan, or subject to any Option, without the receipt of
consideration by the Company (through merger, consolidation, reorganization,
recapitalization, reincorporation, stock dividend, dividend in property other
than cash, stock split, liquidating dividend, combination of shares, exchange of
shares, change in corporate structure or other transaction not involving the
receipt of consideration by the Company), the Plan will be appropriately
adjusted in the class(es) and maximum number of securities subject both to the
Plan pursuant to subsection 4(a) and to the nondiscretionary Options specified
in Section 5, and the outstanding Options will be appropriately adjusted in the
class(es) and number of securities and price per share of stock subject to such
outstanding Options. The Board shall make such adjustments, and its
determination shall be final, binding and conclusive. (The conversion of any
convertible securities of the Company shall not be treated as a transaction
"without receipt of consideration" by the Company.)

         (b) DISSOLUTION OR LIQUIDATION. In the event of a dissolution or
liquidation of the Company, then all outstanding Options shall terminate
immediately prior to such event.

         (c) CORPORATE TRANSACTION. In the event of (i) a sale, lease or other
disposition of all or substantially all of the securities or assets of the
Company, (ii) a merger or consolidation in which the Company is not the
surviving corporation or (iii) a reverse merger in which the Company is the
surviving corporation but the shares of Common Stock outstanding immediately
preceding the merger are converted by virtue of the merger into other property,
whether in the form of securities, cash or otherwise that occurs more than six
(6) months after the adoption of this Plan (each, a "Corporate Transaction"),
then any surviving corporation or acquiring 


                                       8.

<PAGE>

corporation shall assume any Options outstanding under the Plan or shall
substitute similar Options (including an option to acquire the same
consideration paid to the stockholders in the Corporate Transaction for those
outstanding under the Plan). In the event any surviving corporation or acquiring
corporation refuses to assume such Options or to substitute similar Options for
those outstanding under the Plan, then with respect to Options held by
Optionholders whose Continuous Service has not terminated, the vesting of such
Options (and the time during which such Options may be exercised) shall be
accelerated in full, and the Options shall terminate if not exercised at or
prior to the Corporate Transaction. With respect to any other Options
outstanding under the Plan, such Options shall terminate if not exercised prior
to the Corporate Transaction.

12.      AMENDMENT OF THE PLAN AND OPTIONS.

         (a) AMENDMENT OF PLAN. The Board at any time, and from time to time,
may amend the Plan. However, except as provided in Section 11 relating to
adjustments upon changes in stock, no amendment shall be effective unless
approved by the stockholders of the Company to the extent stockholder approval
is necessary to satisfy the requirements of Rule 16b-3 or any Nasdaq or
securities exchange listing requirements.

         (b) STOCKHOLDER APPROVAL. The Board may, in its sole discretion, submit
any other amendment to the Plan for stockholder approval.

         (c) NO IMPAIRMENT OF RIGHTS. Rights under any Option granted before
amendment of the Plan shall not be impaired by any amendment of the Plan unless
(i) the Company requests the consent of the Optionholder and (ii) the
Optionholder consents in writing.

         (d) AMENDMENT OF OPTIONS. The Board at any time, and from time to time,
may amend the terms of any one or more Options; provided, however, that the
rights under any Option shall not be impaired by any such amendment unless (i)
the Company requests the consent of the Optionholder and (ii) the Optionholder
consents in writing.

13.      TERMINATION OR SUSPENSION OF THE PLAN.

         (a) PLAN TERM. The Board may suspend or terminate the Plan at any time.
Unless sooner terminated, the Plan shall terminate on the day before the tenth
(10th) anniversary of the date the Plan is adopted by the Board or approved by
the stockholders of the Company, whichever is earlier. No Options may be granted
under the Plan while the Plan is suspended or after it is terminated.

         (b) NO IMPAIRMENT OF RIGHTS. Suspension or termination of the Plan
shall not impair rights and obligations under any Option granted while the Plan
is in effect except with the written consent of the Optionholder.

14.      EFFECTIVE DATE OF PLAN.

         The Plan shall become effective on the IPO Date, but no Option shall be
exercised unless and until the Plan has been approved by the stockholders of the
Company, which approval shall be within twelve (12) months before or after the
date the Plan is adopted by the Board.


                                       9.

<PAGE>

15.      CHOICE OF LAW.

         All questions concerning the construction, validity and interpretation
of this Plan shall be governed by the law of the State of California, without
regard to such state's conflict of laws rules.

















                                      10.


<PAGE>

                           ACADIA PHARMACEUTICALS INC.
                            STOCK OPTION GRANT NOTICE

                                  ANNUAL GRANT
                (2000 NON-EMPLOYEE DIRECTORS' STOCK OPTION PLAN)


ACADIA PHARMACEUTICALS INC. (the "Company"), pursuant to its 2000 Non-Employee
Directors' Stock Option Plan (the "Plan"), hereby grants to Optionholder an
option to purchase the number of shares of the Company's Common Stock set forth
below. This option is subject to all of the terms and conditions as set forth
herein and in the Stock Option Agreement, the Plan and the Notice of Exercise,
all of which are attached hereto and incorporated herein in their entirety.

Optionholder:                               ___________________________________
Date of Grant:                              ___________________________________
Number of Shares Subject to Option:         ___________________________________
Exercise Price (Per Share):                 ___________________________________
Total Exercise Price:                       ___________________________________
Expiration Date:                            The day before the 10th anniversary
                                            of the Date of Grant

TYPE OF GRANT:      Nonstatutory Stock Option

EXERCISE SCHEDULE:  Same as Vesting Schedule

VESTING SCHEDULE:   1/4th  of the shares vest at the end of each three month 
                    period following the Date of Grant.

PAYMENT:            By one or a combination of the following items (described 
                    in the Stock Option Agreement):

                             By cash or check
                             Pursuant to a Regulation T Program if the Shares
                             are publicly traded 
                             By delivery of already-owned shares if the Shares
                             are publicly traded

ADDITIONAL TERMS/ACKNOWLEDGEMENTS: The undersigned Optionholder acknowledges
receipt of, and understands and agrees to, this Grant Notice, the Stock Option
Agreement and the Plan. Optionholder further acknowledges that as of the Date of
Grant, this Grant Notice, the Stock Option Agreement and the Plan set forth the
entire understanding between Optionholder and the Company regarding the
acquisition of stock in the Company and supersede all prior oral and written
agreements on that subject with the exception of (i) options previously granted
and delivered to Optionholder under the Plan, and (ii) the following agreements
only:

         OTHER AGREEMENTS:               _______________________________________
                                         _______________________________________

ACADIA PHARMACEUTICALS INC.                 OPTIONHOLDER:


By:_____________________________________   _____________________________________
                Signature                              Signature

Title:__________________________________   Date:________________________________


Date:___________________________________
     

ATTACHMENTS:   Stock Option Agreement, 2000 Non-Employee Directors' Stock 
               Option Plan and Notice of Exercise


<PAGE>

                           ACADIA PHARMACEUTICALS INC.
                            STOCK OPTION GRANT NOTICE

                                  INITIAL GRANT
                (2000 NON-EMPLOYEE DIRECTORS' STOCK OPTION PLAN)


ACADIA PHARMACEUTICALS INC. (the "Company"), pursuant to its 2000 Non-Employee
Directors' Stock Option Plan (the "Plan"), hereby grants to Optionholder an
option to purchase the number of shares of the Company's Common Stock set forth
below. This option is subject to all of the terms and conditions as set forth
herein and in the Stock Option Agreement, the Plan and the Notice of Exercise,
all of which are attached hereto and incorporated herein in their entirety.

Optionholder:                            _______________________________________
Date of Grant:                           _______________________________________
Number of Shares Subject to Option:      _______________________________________
Exercise Price (Per Share):              _______________________________________
Total Exercise Price:                    _______________________________________
Expiration Date:                         The day before the 10th anniversary of
                                         the Date of Grant

TYPE OF GRANT:     Nonstatutory Stock Option

EXERCISE SCHEDULE: Same as Vesting Schedule

VESTING SCHEDULE:  1/3rd of the shares vest one year following the Date of
                   Grant and 1/12th of the shares vest at the end of each three 
                   month period thereafter.

PAYMENT:           By one or a combination of the following items (described in 
                   the Stock Option Agreement):

                            By cash or check
                            Pursuant to a Regulation T Program if the Shares
                            are publicly traded 
                            By delivery of already-owned shares if the Shares 
                            are publicly traded

ADDITIONAL TERMS/ACKNOWLEDGEMENTS: The undersigned Optionholder acknowledges
receipt of, and understands and agrees to, this Grant Notice, the Stock Option
Agreement and the Plan. Optionholder further acknowledges that as of the Date of
Grant, this Grant Notice, the Stock Option Agreement and the Plan set forth the
entire understanding between Optionholder and the Company regarding the
acquisition of stock in the Company and supersede all prior oral and written
agreements on that subject with the exception of (i) options previously granted
and delivered to Optionholder under the Plan, and (ii) the following agreements
only:

         OTHER AGREEMENTS:         _____________________________________________
                                   _____________________________________________

ACADIA PHARMACEUTICALS INC.                   OPTIONHOLDER:


By:_____________________________________      _________________________________
              Signature                                  Signature

Title:__________________________________      Date:____________________________


Date:___________________________________


ATTACHMENTS:  Stock Option Agreement, 2000 Non-Employee Directors' Stock Option
              Plan and Notice of Exercise


<PAGE>

                           ACADIA PHARMACEUTICALS INC.
                 2000 NON-EMPLOYEE DIRECTORS' STOCK OPTION PLAN


                             STOCK OPTION AGREEMENT
                           (NONSTATUTORY STOCK OPTION)


         Pursuant to your Stock Option Grant Notice ("Grant Notice") and this
Stock Option Agreement, ACADIA Pharmaceuticals Inc. (the "Company") has granted
you an option under its 2000 Non-Employee Directors' Stock Option Plan (the
"Plan") to purchase the number of shares of the Company's Common Stock indicated
in your Grant Notice at the exercise price indicated in your Grant Notice.
Defined terms not explicitly defined in this Stock Option Agreement but defined
in the Plan shall have the same definitions as in the Plan.

The details of your option are as follows:

         1. VESTING. Subject to the limitations contained herein, your option
will vest as provided in your Grant Notice, provided that vesting will cease
upon the termination of your Continuous Service.

         2. NUMBER OF SHARES AND EXERCISE PRICE. The number of shares of Common
Stock subject to your option and your exercise price per share referenced in
your Grant Notice may be adjusted from time to time for Capitalization
Adjustments, as provided in the Plan.

         3. METHOD OF PAYMENT. Payment of the exercise price is due in full upon
exercise of all or any part of your option. You may elect to make payment of the
exercise price in cash or by check or in any other manner PERMITTED BY YOUR
GRANT NOTICE, which may include one or more of the following:

                  (a) In the Company's sole discretion at the time your option
is exercised and provided that at the time of exercise the Common Stock is
publicly traded and quoted regularly in THE WALL STREET JOURNAL, pursuant to a
program developed under Regulation T as promulgated by the Federal Reserve Board
that, prior to the issuance of Common Stock, results in either the receipt of
cash (or check) by the Company or the receipt of irrevocable instructions to pay
the aggregate exercise price to the Company from the sales proceeds.

                  (b) Provided that at the time of exercise the Common Stock is
publicly traded and quoted regularly in THE WALL STREET JOURNAL, by delivery of
already-owned shares of Common Stock either that you have held for the period
required to avoid a charge to the Company's reported earnings (generally six
months) or that you did not acquire, directly or indirectly from the Company,
that are owned free and clear of any liens, claims, encumbrances or security
interests, and that are valued at Fair Market Value on the date of exercise.
"Delivery" for these purposes, in the sole discretion of the Company at the time
you exercise your option, shall include delivery to the Company of your
attestation of ownership of such shares of Common Stock in a form approved by
the Company. Notwithstanding the foregoing, you may not exercise your option by
tender to the Company of Common Stock to the extent such tender


                                       1.

<PAGE>

would violate the provisions of any law, regulation or agreement restricting the
redemption of the Company's stock.

         4. WHOLE SHARES. You may exercise your option only for whole shares of
Common Stock.

         5. SECURITIES LAW COMPLIANCE. Notwithstanding anything to the contrary
contained herein, you may not exercise your option unless the shares of Common
Stock issuable upon such exercise are then registered under the Securities Act
or, if such shares of Common Stock are not then so registered, the Company has
determined that such exercise and issuance would be exempt from the registration
requirements of the Securities Act. The exercise of your option must also comply
with other applicable laws and regulations governing your option, and you may
not exercise your option if the Company determines that such exercise would not
be in material compliance with such laws and regulations.

         6. TERM. You may not exercise your option before the commencement of
its term or after its term expires. The term of your option commences on the
Date of Grant and expires upon the EARLIEST of the following:

                  (a) three (3) months after the termination of your Continuous
Service for any reason other than your Disability or death, provided that if
during any part of such three- (3-) month period your option is not exercisable
solely because of the condition set forth in the preceding paragraph relating to
"Securities Law Compliance," your option shall not expire until the earlier of
the Expiration Date or until it shall have been exercisable for an aggregate
period of three (3) months after the termination of your Continuous Service;

                  (b) twelve (12) months after the termination of your
Continuous Service due to your Disability;

                  (c) eighteen (18) months after your death if you die either
during your Continuous Service or within three (3) months after your Continuous
Service terminates;

                  (d) the Expiration Date indicated in your Grant Notice; or

                  (e) the day before the tenth (10th) anniversary of the Date of
Grant.

         7. EXERCISE.

                  (a) You may exercise the vested portion of your option (and
the unvested portion of your option if your Grant Notice so permits) during its
term by delivering a Notice of Exercise (in a form designated by the Company)
together with the exercise price to the Secretary of the Company, or to such
other person as the Company may designate, during regular business hours,
together with such additional documents as the Company may then require.

                  (b) By exercising your option you agree that, as a condition
to any exercise of your option, the Company may require you to enter into an
arrangement providing for the payment by you to the Company of any tax
withholding obligation of the Company arising by reason of (1) the exercise of
your option, (2) the lapse of any substantial risk of forfeiture to 


                                       2.

<PAGE>

which the shares of Common Stock are subject at the time of exercise, or (3) the
disposition of shares of Common Stock acquired upon such exercise.

         8. TRANSFERABILITY. Your option is transferable to the extent provided
in the Plan and by will or by the laws of descent and distribution. In addition,
by delivering written notice to the Company, in a form satisfactory to the
Company, you may designate a third party who, in the event of your death, shall
thereafter be entitled to exercise your option.

         9. OPTION NOT A SERVICE CONTRACT. Your option is not an employment or
service contract, and nothing in your option shall be deemed to create in any
way whatsoever any obligation on your part to continue in the employ of the
Company or an Affiliate, or of the Company or an Affiliate to continue your
employment. In addition, nothing in your option shall obligate the Company or an
Affiliate, their respective stockholders, Boards of Directors, Officers or
Employees to continue any relationship that you might have as a Director or
Consultant for the Company or an Affiliate.

         10. WITHHOLDING OBLIGATIONS.

                  (a) At the time you exercise your option, in whole or in part,
or at any time thereafter as requested by the Company, you hereby authorize
withholding from payroll and any other amounts payable to you, and otherwise
agree to make adequate provision for (including by means of a "cashless
exercise" pursuant to a program developed under Regulation T as promulgated by
the Federal Reserve Board to the extent permitted by the Company), any sums
required to satisfy the federal, state, local and foreign tax withholding
obligations of the Company or an Affiliate, if any, which arise in connection
with your option.

                  (b) Upon your request and subject to approval by the Company,
in its sole discretion, and compliance with any applicable conditions or
restrictions of law, the Company may withhold from fully vested shares of Common
Stock otherwise issuable to you upon the exercise of your option a number of
whole shares of Common Stock having a Fair Market Value, determined by the
Company as of the date of exercise, not in excess of the minimum amount of tax
required to be withheld by law. If the date of determination of any tax
withholding obligation is deferred to a date later than the date of exercise of
your option, share withholding pursuant to the preceding sentence shall not be
permitted unless you make a proper and timely election under Section 83(b) of
the Code, covering the aggregate number of shares of Common Stock acquired upon
such exercise with respect to which such determination is otherwise deferred, to
accelerate the determination of such tax withholding obligation to the date of
exercise of your option. Notwithstanding the filing of such election, shares of
Common Stock shall be withheld solely from fully vested shares of Common Stock
determined as of the date of exercise of your option that are otherwise issuable
to you upon such exercise. Any adverse consequences to you arising in connection
with such share withholding procedure shall be your sole responsibility.

                  (c) You may not exercise your option unless the tax
withholding obligations of the Company and/or any Affiliate are satisfied.
Accordingly, you may not be able to exercise your option when desired even
though your option is vested, and the Company shall have no 


                                       3.

<PAGE>

obligation to issue a certificate for such shares of Common Stock or release
such shares of Common Stock from any escrow provided for herein.

         11. NOTICES. Any notices provided for in your option or the Plan shall
be given in writing and shall be deemed effectively given upon receipt or, in
the case of notices delivered by mail by the Company to you, five (5) days after
deposit in the United States mail, postage prepaid, addressed to you at the last
address you provided to the Company.

         12. GOVERNING PLAN DOCUMENT. Your option is subject to all the
provisions of the Plan, the provisions of which are hereby made a part of your
option, and is further subject to all interpretations, amendments, rules and
regulations which may from time to time be promulgated and adopted pursuant to
the Plan. In the event of any conflict between the provisions of your option and
those of the Plan, the provisions of the Plan shall control.




















                                       4.

<PAGE>

                               NOTICE OF EXERCISE



ACADIA Pharmaceuticals Inc.
3911 Sorrento Valley Blvd.
San Diego, CA 92121                            Date of Exercise: _______________

Ladies and Gentlemen:

         This constitutes notice under my stock option that I elect to purchase
the number of shares for the price set forth below.

         Stock option dated:                    _______________
         Number of shares as
         to which option is
         exercised:                             _______________
         Certificates to be
         issued in name of:                     _______________
         Total exercise price:                  $______________
         Cash payment delivered
         herewith:                              $______________
         Value of ________ shares of
         ACADIA Pharmaceuticals Inc. 
         common stock delivered herewith(1):    $______________

         By this exercise, I agree (i) to provide such additional documents as
you may require pursuant to the terms of the ACADIA Pharmaceuticals, Inc. 2000
Non-Employee Directors' Stock Option Plan, (ii) to provide for the payment by me
to you (in the manner designated by you) of your withholding obligation, if any,
relating to the exercise of this option, and (iii) if this exercise relates to
an incentive stock option, to notify you in writing within fifteen (15) days
after the date of any disposition of any of the shares of Common Stock issued
upon exercise of this option that occurs within two (2) years after the date of
grant of this option or within one (1) year after such shares of Common Stock
are issued upon exercise of this option.

                                                Very truly yours,


                                                ________________________________
         
__________________________

(1)      Shares must meet the public trading requirements set forth in the
option. Shares must be valued in accordance with the terms of the option being
exercised, must have been owned for the minimum period required in the option,
and must be owned free and clear of any liens, claims, encumbrances or security
interests. Certificates must be endorsed or accompanied by an executed
assignment separate from certificate.



<PAGE>

                           ACADIA PHARMACEUTICALS INC.
                        2000 EMPLOYEE STOCK PURCHASE PLAN

               ADOPTED BY THE BOARD OF DIRECTORS DECEMBER 20, 2000
                  APPROVED BY STOCKHOLDERS ____________, 200___


1.       PURPOSE.

         (a) The purpose of the Plan is to provide a means by which Employees of
the Company and certain designated Related Corporations may be given an
opportunity to purchase shares of the Common Stock of the Company.

         (b) The Company, by means of the Plan, seeks to retain the services of
such Employees, to secure and retain the services of new Employees and to
provide incentives for such persons to exert maximum efforts for the success of
the Company and its Related Corporations.

         (c) The Company intends that the Purchase Rights granted under the Plan
be considered options issued under an Employee Stock Purchase Plan.

2.       DEFINITIONS.

         (a) "ANNUAL MEETING" means the annual meeting of the stockholders of
the Company.

         (b) "BOARD" means the Board of Directors of the Company.

         (c) "CODE" means the Internal Revenue Code of 1986, as amended.

         (d) "COMMITTEE" means a committee appointed by the Board in accordance
with Section 3(c) of the Plan.

         (e) "COMMON STOCK" means the Common Stock of the Company.

         (f) "COMPANY" means ACADIA Pharmaceuticals Inc., a Delaware
corporation.

         (g) "CORPORATE TRANSACTION" means
 the occurrence of any one or more of
the following:

                  (i) a sale, exchange or other disposition of all or
substantially all of the assets of the Company;

                  (ii) a sale, exchange or other disposition of all or
substantially all of the outstanding securities of the Company;


                                     - 1 -

<PAGE>

                  (iii) a merger or consolidation following which the Company is
not the surviving corporation;

                  (iv) a merger following which the Company is the surviving
corporation but the shares of Common Stock outstanding immediately preceding the
merger are converted by virtue of the merger into other property, whether in the
form of securities, cash or otherwise; or

                  (v) any other transaction described as a "corporate
transaction" in Treasury Regulations Section 1.425-1(a)(1)(ii), as amended from
time to time.

         (h) "DIRECTOR" means a member of the Board.

         (i) "ELIGIBLE EMPLOYEE" means an Employee who meets the requirements
set forth in the Offering for eligibility to participate in the Offering,
provided that such Employee also meets the requirements for eligibility to
participate set forth in the Plan.

         (j) "EMPLOYEE" means any person, including Officers and Directors, who
is employed for purposes of Section 423(b)(4) of the Code by the Company or a
Related Corporation. Neither service as a Director nor payment of a director's
fee shall be sufficient to make an individual an Employee of the Company or a
Related Corporation.

         (k) "EMPLOYEE STOCK PURCHASE PLAN" means a plan that grants Purchase
Rights intended to be options issued under an "employee stock purchase plan," as
that term is defined in Section 423(b) of the Code.

         (l) "EXCHANGE ACT" means the Securities Exchange Act of 1934, as
amended.

         (m) "FAIR MARKET VALUE" means the value of a security, as determined in
good faith by the Board. If the security is listed on any established stock
exchange or traded on the Nasdaq National Market or the Nasdaq SmallCap Market,
the Fair Market Value of the security, unless otherwise determined by the Board,
shall be the closing sales price (rounded up where necessary to the nearest
whole cent) for such security (or the closing bid, if no sales were reported) as
quoted on such exchange or market (or the exchange or market with the greatest
volume of trading in the relevant security of the Company) on the Trading Day
prior to the relevant determination date, as reported in THE WALL STREET JOURNAL
or such other sourc