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                           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


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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.


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         (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.
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         (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.
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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.


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         (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.
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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.