<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.

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         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