Document:

<PAGE>   1
                                                                     EXHIBIT 4.1

                             CONNETICS CORPORATION
                       1995 EMPLOYEE STOCK PURCHASE PLAN
                         (AS AMENDED THROUGH MAY 2000)
                Adopted by the Board of Directors Feb. 17, 2000
                   Approved by the Stockholders May 11, 2000

The following constitute the provisions of the 1995 Employee Stock Purchase Plan
of Connetics Corporation, as amended.

1.   PURPOSE. The purpose of the Plan is to provide employees of the Company and
its Designated Subsidiaries with an opportunity to purchase Common Stock of the
Company. It is the intention of the Company to have the Plan qualify as an
"Employee Stock Purchase Plan" under Section 423 of the Internal Revenue Code of
1986, as amended. The provisions of the Plan shall, accordingly, be construed so
as to extend and limit participation in a manner consistent with the
requirements of that section of the Code.

2.   DEFINITIONS.

     (a)  "Board" means the Board of Directors of the Company.

     (b)  "Code" means the Internal Revenue Code of 1986, as amended.

     (c)  "Common Stock" means the Common Stock of the Company.

     (d)  "Company" means Connetics Corporation a Delaware corporation.

     (e)  "Compensation" means all regular straight time gross earnings,
excluding payments for overtime, shift premium, incentive compensation,
incentive payments, bonuses, commissions and other compensation.

     (f)  "Continuous Status as an Employee" means the absence of any
interruption or termination of service as an Employee. Continuous Status as an
Employee shall not be considered interrupted in the case of a leave of absence
agreed to in writing by the Company, provided that such leave is for a period of
not more than 90 days or reemployment upon the expiration of such leave is
guaranteed by contract or statute.

     (g)  "Contributions" means all amounts credited to the account of a
participant pursuant to the Plan.

     (h)  "Designated Subsidiaries" means the Subsidiaries which have been
designated by the Board from time to time in its sole discretion as eligible to
participate in the Plan.

     (i)  "Employee" means any person, including an Officer, who is customarily
employed for at least twenty (20) hours per week and more than five (5) months
in a calendar year by the Company or one of its Designated Subsidiaries.

     (j)  "Exchange Act" means the Securities Exchange Act of 1934, as amended.

<PAGE>   2

     (k)  "Purchase Date" means the last day of each Purchase Period of the
Plan.

     (l)  "Offering" means the grant of rights to purchase Common Stock of the
Company under the Plan to eligible Employees.

     (m)  "Offering Date" means the first business day of each Offering Period
of the Plan. In the case of an individual who becomes an eligible Employee after
the first business day of an Offering Period but prior to the first business day
of the last calendar quarter of such Offering Period, the term "Offering Date"
means the first business day of the calendar quarter coinciding with or next
succeeding the day on which that individual becomes an eligible Employee.
Options granted after the first business day of an Offering Period will be
subject to the same terms as the options granted on the first business day of
such Offering Period except that they will have a different grant date (thus,
potentially, a different exercise price) and, because they expire at the same
time as the options granted on the first business day of such Offering Period, a
shorter term.

     (n)  "Offering Period" means a period of twelve (12) months commencing on
December 1 and June 1 of each year, except as otherwise set forth in SECTION
4(a), or such other period as the Board of Directors may determine prior to the
commencement of an Offering Period, but which period shall not exceed
twenty-four (24) months.

     (o)  "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 under the Exchange Act.

     (p)  "Option Price" means the price at which the shares are offered in a
given Offering Period, calculated as set forth in SECTION 7(b).

     (q)  "Plan" means this Employee Stock Purchase Plan.

     (r)  "Purchase Period" means a period of six (6) months within an Offering
Period.

     (s)  "Subsidiary" means a corporation, domestic or foreign, of which not
less than 50% of the voting shares are held by the Company or a Subsidiary,
whether or not such corporation now exists or is hereafter organized or acquired
by the Company or a Subsidiary.

3.   ELIGIBILITY.

     (a)  Any person who is an Employee as of the Offering Date of a given
Offering Period shall be eligible to participate in such Offering Period under
the Plan subject to the requirements of SECTION 5(a) and the limitations imposed
by Section 423(b) of the Code.

     (b)  Any provisions of the Plan to the contrary notwithstanding, no
Employee shall be granted an option under the Plan (i) if, immediately after the
grant, such Employee (or any other person whose stock would be attributed to
such Employee pursuant to Section 424(d) of the Code) would own stock and/or
hold outstanding options to purchase stock possessing five percent (5%) or more
of the total combined voting power or value of all classes of stock of the
Company or of any subsidiary of the Company, or (ii) if such option would permit
his or her rights to purchase stock under all employee stock purchase plans
(described in Section 423 of the Code) of the Company and its Subsidiaries to
accrue at a rate which exceeds Twenty-Five Thousand Dollars ($25,000) of fair
market value of such stock

                                       2
<PAGE>   3
(determined at the time such option is granted) for each calendar year in which
such option is outstanding at any time.

4.   OFFERING PERIODS AND PURCHASE PERIODS.

     (a)  Offering Periods. The Plan shall be implemented by a series of
Offering Periods of twelve (12) months duration, with new Offering Periods
commencing on or about June 1 and December 1 of each year (or at such other time
or times as may be determined by the Board of Directors). In particular, upon
adoption of this Plan as amended, a new Offering Period shall commence on June
1, 2000, and any Offering Periods in effect prior to that date shall be
terminated effective May 31, 2000. The Plan shall continue until terminated in
accordance with SECTION 20 of this Plan. The Board of Directors of the Company
shall have the power to change the duration and/or the frequency of Offering
Periods with respect to future offerings without stockholder approval if such
change is announced at least fifteen (15) days prior to the scheduled beginning
of the first Offering Period to be affected. The terms and conditions of an
Offering Period shall be incorporated by reference into the Plan and treated as
part of the Plan. The provisions of separate Offering Periods need not be
identical, but each Offering shall include (thorough incorporation of the
provisions of this Plan by reference into the document comprising the Offering
or otherwise) the Offering Period, and the substance of the provisions contained
in SECTIONS 5 through 13, inclusive. An Employee may only participate in one
Offering Period at a time.

     (b)  Purchase Periods. Each Offering Period shall consist of two (2)
consecutive purchase periods of six (6) months duration, unless the Board
approves a longer Offering Period. The last day of each Purchase Period shall be
the "Purchase Date" for such Purchase Period. A Purchase Period commencing on
June 1 shall end on the next November 30. A Purchase Period commencing on
December 1 shall end on the next May 31. In particular, upon adoption of this
Plan as amended, a new Purchase Period shall commence on June 1, 2000, and any
Purchase Periods in effect prior to that date shall be terminated effective May
31, 2000. The Board of Directors of the Company shall have the power to change
the duration and/or frequency of Purchase Periods with respect to future
purchases without stockholder approval if such change is announced at least
fifteen (15) days prior to the scheduled beginning of the first Purchase Period
to be affected.

5.   PARTICIPATION.

     (a)  An eligible Employee may become a participant in the Plan by
completing a subscription agreement on the form provided by the Company and
filing it with the Company's payroll office prior to the applicable Offering
Date, unless a later time for filing the subscription agreement is set by the
Board for all eligible Employees with respect to a given offering. The
subscription agreement shall set forth the percentage of the participant's
Compensation (which shall be not less than 1% and not more than 15%) to be paid
as Contributions pursuant to the Plan.

     (b)  Payroll deductions shall commence on the first payroll following the
Offering Date and shall end on the last payroll paid on or prior to the last
Purchase Period of the Offering Period to which the subscription agreement is
applicable, unless sooner terminated by the participant as provided in SECTION
10.

6.   METHOD OF PAYMENT OF CONTRIBUTIONS.

                                       3
<PAGE>   4

     (a)  The participant shall elect to have payroll deductions made on each
payday during the Offering Period in an amount not less than one percent (1%)
and not more than fifteen percent (15%) of such participant's Compensation on
each such payday. All payroll deductions made by a participant shall be credited
to his or her account under the Plan. A participant may not make any additional
payments into such account.

     (b)  A participant may discontinue his or her participation in the Plan as
provided in SECTION 10, or, on one occasion only during the Offering Period, may
increase or decrease the rate of his or her Contributions during the Offering
Period by completing and filing with the Company a new subscription agreement.
The change in rate shall be effective as of the beginning of the calendar
quarter following the date of filing of the new subscription agreement.

     (c)  Notwithstanding the foregoing, to the extent necessary to comply with
Section 423(b)(8) of the Code and SECTION 3(b) of this Plan, a participant's
payroll deductions may be decreased to 0% at such time during any Offering
Period which is scheduled to end during the current calendar year that the
aggregate of all payroll deductions accumulated with respect to such Offering
Period and any other Offering Period ending within the same calendar year equal
$25,000. Payroll deductions shall recommence at the rate provided in such
participant's subscription Agreement at the beginning of the first Offering
Period which is scheduled to end in the following calendar year, unless
terminated by the participant as provided in SECTION 10.

7.   GRANT OF OPTION.

     (a)  On the Offering Date of each Offering Period, each eligible Employee
participating in such Offering Period shall be granted an option to purchase on
each Purchase Date a number of shares of the Company's Common Stock determined
by dividing such Employee's Contributions accumulated prior to such Purchase
Date and retained in the participant's account as of the Purchase Date by the
Option Price; provided however, that the maximum number of shares an Employee
may purchase during each Offering Period shall be determined at the Offering
Date by dividing $50,000 by the fair market value of a share of the Company's
Common Stock on the Offering Date, and provided further that such purchase shall
be subject to the limitations set forth in SECTIONS 3(b) and 12. The fair market
value of a share of the Company's Common Stock shall be determined as provided
in SECTION 7(b).

     (b)  The option price per share of the shares offered in a given Offering
Period ("Option Price") shall be the lower of:

     (i)  eighty-five percent (85%) of the fair market value of a share of the
          Company's Common Stock on the Offering Date, or

     (ii) eighty-five percent (85%) of the fair market value of a share of the
          Company's Common Stock on the Purchase Date;

The fair market value of the Company's Common Stock on a given date shall be
determined by the Board in its discretion based on the closing price of the
Common Stock for such date (or, in the event that the Common Stock is not traded
on such date, on the immediately preceding trading date), as reported by the
National Association of Securities Dealers Automated Quotation (Nasdaq) National
Market or, if such price is not reported, the mean of the bid and asked prices
per share of the Common Stock as reported by Nasdaq or, in the event the Common
Stock is listed on a stock exchange, the fair market value per share shall be
the closing price on such exchange on such date (or, in the event that the
Common Stock is not traded on such date, on the immediately preceding trading
date), as reported in The Wall Street Journal.

                                       4
<PAGE>   5

     (c)  In connection with each Offering made under the Plan, the Board or the
Committee may specify a maximum number of shares that may be purchased by any
employee as well as a maximum aggregate number of shares that may be purchased
by all eligible employees pursuant to such Offering. In addition, in connection
with each Offering that contains more than one Purchase Date, the Board or the
Committee may specify a maximum aggregate number of shares which may be
purchased by all eligible employees on any give Purchase Date under the
Offering. If the aggregate purchase of shares upon exercise of rights granted
under the Offering would exceed any such maximum aggregate number, the Board or
the Committee shall make a pro rata allocation of the shares available in as
nearly a uniform manner as is practicable and as it deems to be equitable.

8.   EXERCISE OF OPTION. Unless a participant withdraws from the Plan as
provided in SECTION 10, his or her option for the purchase of shares will be
exercised automatically on each Purchase Date of an Offering Period, and the
maximum number of shares, including fractional shares, subject to the option
will be purchased at the applicable option price with the accumulated
Contributions in his or her account. The shares purchased upon exercise of an
option hereunder shall be deemed to be transferred to the participant on the
Purchase Date. During his or her lifetime, a participant's option to purchase
shares hereunder is exercisable only by him or her.

9.   DELIVERY. As promptly as practicable after each Purchase Date of each
Offering Period, the Company shall arrange the delivery to each participant, as
appropriate, of a certificate representing the shares purchased upon exercise of
his or her option or the deposit of such number of shares with the broker
selected by the Company for administration of Plan stock purchases, as
determined by the Company. Any cash remaining to the credit of a participant's
account under the Plan after a purchase by him or her of shares at the
termination of each Offering Period, or which is insufficient to purchase a full
share of Common Stock of the Company, shall be carried over to the next Offering
Period if the Employee continues to participate in the Plan, or if the Employee
does not continue to participate, shall be returned to said participant.

10.     VOLUNTARY WITHDRAWAL; TERMINATION OF EMPLOYMENT.

     (a)  A participant may withdraw all but not less than all the Contributions
credited to his or her account under the Plan at any time prior to each Purchase
Date by giving written notice to the Company. All of the participant's
Contributions credited to his or her account will be paid to him or her promptly
after receipt of his or her notice of withdrawal and his or her option for the
current period will be automatically terminated, and no further Contributions
for the purchase of shares will be made during the Offering Period.

     (b)  Upon termination of the participant's Continuous Status as an Employee
prior to the Purchase Date of an Offering Period for any reason, including
retirement or death, the Contributions credited to his or her account will be
returned to him or her or, in the case of his or her death, to the person or
persons entitled thereto under SECTION 14, and his or her option will be
automatically terminated.

     (c)  If an Employee fails to remain in Continuous Status as an Employee of
the Company for at least twenty (20) hours per week during the Offering Period
in which the employee is a participant, he or she will be deemed to have elected
to withdraw from the Plan and the Contributions credited to his or her account
will be returned to him or her and his or her option terminated.

     (d)  A participant's withdrawal from an offering will not have any effect
upon his or her eligibility to participate in a succeeding offering or in any
similar plan which the Company may adopt after the date of this Plan.

                                       5
<PAGE>   6

11.  AUTOMATIC WITHDRAWAL. On each Purchase Date, if the fair market value of
the shares is lower than it was on the immediately preceding Offering Date, all
participants whose Offering Period commenced on the immediately preceding
Offering Date shall (a) acquire the shares reserved for the participant for such
Purchase Period, and (b) automatically be (i) withdrawn from the Offering Period
in which they are enrolled at the close of such Purchase Date following the
acquisition of shares, and (ii) enrolled in the Offering Period that commences
on the next business day.

12.  INTEREST. No interest shall accrue on the Contributions of a participant in
the Plan.

13.  STOCK SUBJECT TO THE PLAN.

     (a)  Subject to adjustment upon changes in capitalization of the Company as
provided in SECTION 18, the maximum aggregate number of Shares which may be
optioned and sold under the Plan shall be Eight Hundred Thousand (800,000)
shares, plus an annual increase to be added on each November 30, equal to the
lesser of:

     (i)  one half of one percent (0.5%) of the total number of shares of Common
          Stock outstanding on such anniversary date; or

     (ii) a number of shares determined by the Board prior to the anniversary
          date, which number shall be less than (i) above.

The Shares may be authorized, but unissued, or reacquired Common Stock. If the
total number of shares which would otherwise be subject to options granted
pursuant to SECTION 7(a) on the Offering Date of an Offering Period exceeds the
number of shares then available under the Plan (after deduction of all shares
for which options have been exercised or are then outstanding), the Company
shall make a pro rata allocation of the shares remaining available for option
grant in as uniform a manner as shall be practicable and as it shall determine
to be equitable. In such event, the Company shall give written notice of such
reduction of the number of shares subject to the option to each Employee
affected thereby and shall similarly reduce the rate of Contributions, if
necessary.

     (b)  The participant will have no interest or voting right in shares
covered by his or her option until such option has been exercised.

     (c)  Shares to be delivered to a participant under the Plan will be
registered in the name of the participant or in the name of the participant and
his or her spouse.

14.  ADMINISTRATION. The Board, or a committee named by the Board, shall
supervise and administer the Plan and shall have full power to adopt, amend and
rescind any rules deemed desirable and appropriate for the administration of the
Plan and not inconsistent with the Plan, to determine when and how rights to
purchase stock of the Company shall be granted and the provisions of each such
Offering Period (which need not be identical), to construe and interpret the
Plan and rights granted under it, and to establish, amend and revoke rules and
regulations for the administration of the Plan. The composition of the committee
shall be in accordance with the requirements to obtain or retain any available
exemption from the operation of Section 16(b) of the Exchange Act pursuant to
Rule 16b-3 under the Exchange Act.

                                       5
<PAGE>   7

15.  DESIGNATION OF BENEFICIARY.

     (a)  A participant may file a written designation of a beneficiary who is
to receive any shares and cash, if any, from the participant's account under the
Plan in the event of such participant's death subsequent to the end of a
Purchase Period but prior to delivery to him or her of such shares and cash. In
addition, a participant may file a written designation of a beneficiary who is
to receive any cash from the participant's account under the Plan in the event
of such participant's death prior to the Purchase Date of an Offering Period. If
a participant is married and the designated beneficiary is not the spouse,
spousal consent shall be required for such designation to be effective.

     (b)  Such designation of beneficiary may be changed by the participant (and
his or her spouse, if any) at any time by written notice. In the event of the
death of a participant and in the absence of a beneficiary validly designated
under the Plan who is living at the time of such participant's death, the
Company shall deliver such shares and/or cash to the executor or administrator
of the estate of the participant, or if no such executor or administrator has
been appointed (to the knowledge of the Company), the Company, in its
discretion, may deliver such shares and/or cash to the spouse or to any one or
more dependents or relatives of the participant, or if no spouse, dependent or
relative is known to the Company, then to such other person as the Company may
designate.

16.  TRANSFERABILITY. Neither Contributions credited to a participant's account
nor any rights with regard to the exercise of an option or to receive shares
under the Plan may be assigned, transferred, pledged or otherwise disposed of in
any way (other than by will, the laws of descent and distribution, or as
provided in SECTION 14) by the participant. Any such attempt at assignment,
transfer, pledge or other disposition shall be without effect, except that the
Company may treat such act as an election to withdraw funds in accordance with
SECTION 10.

17.  USE OF FUNDS. Contributions received by the Company under the Plan shall
constitute general funds of the Company.

18.  REPORTS. Individual accounts will be maintained for each participant in the
Plan. Statements of account will be given to participating Employees promptly
following the Purchase Date, which statements will set forth the amounts of
Contributions, the per share purchase price, the number of shares purchased and
the remaining cash balance, if any.

19.  ADJUSTMENTS UPON CHANGES IN CAPITALIZATION; CORPORATE TRANSACTIONS.

     (a)  Adjustment. Subject to any required action by the shareholders of the
Company, the number of shares of Common Stock covered by each option under the
Plan which has not yet been exercised and the number of shares of Common Stock
which have been authorized for issuance under the Plan but have not yet been
placed under option (collectively, the "Reserves"), as well as the price per
share of Common Stock covered by each option under the Plan which has not yet
been exercised, shall be proportionately adjusted for any increase or decrease
in the number of issued shares of Common Stock resulting from a stock split,
reverse stock split, stock dividend, combination or reclassification of the
Common Stock, or any other increase or decrease in the number of shares of
Common Stock effected without receipt of consideration by the Company; provided,
however, that conversion of any convertible securities of the Company shall not
be deemed to have been "effected without receipt of consideration". Such
adjustment shall be made by the Board, whose determination in that respect shall
be final, binding and conclusive. Except as expressly provided herein, no issue
by the Company of shares of stock of any class, or securities convertible into
shares of stock of any class, shall affect, and no adjustment by reason thereof
shall be made with respect to, the number or price of shares of Common Stock
subject to an option.

                                       6
<PAGE>   8

     (b)  Corporate Transactions. In the event of the proposed dissolution or
liquidation of the Company, the Offering Period will terminate immediately prior
to the consummation of such proposed action, unless otherwise provided by the
Board. In the event of a proposed sale of all or substantially all of the assets
of the Company, or the merger of the Company with or into another corporation,
each option under the Plan shall be assumed or an equivalent option shall be
substituted by such successor corporation or a parent or subsidiary of such
successor corporation, unless the Board determines, in the exercise of its sole
discretion and in lieu of such assumption or substitution, to shorten the
Offering Period then in progress by setting a new Purchase Date (the "New
Purchase Date"). If the Board shortens the Offering Period then in progress in
lieu of assumption or substitution in the event of a merger or sale of assets,
the Board shall notify each participant in writing, at least ten (10) days prior
to the New Purchase Date, that the Purchase Date for his or her option has been
changed to the New Purchase Date and that his or her option will be exercised
automatically on the New Purchase Date, unless prior to such date he or she has
withdrawn from the Offering Period as provided in SECTION 10. For purposes of
this paragraph, an option granted under the Plan shall be deemed to be assumed
if, following the sale of assets or merger, the option confers the right to
purchase, for each share of option stock subject to the option immediately prior
to the sale of assets or merger, the consideration (whether stock, cash or other
securities or property) received in the sale of assets or merger by holders of
Common Stock for each share of Common Stock held on the effective date of the
transaction (and if such holders were offered a choice of consideration, the
type of consideration chosen by the holders of a majority of the outstanding
shares of Common Stock); provided, however, that if such consideration received
in the sale of assets or merger was not solely common stock of the successor
corporation or its parent (as defined in Section 424(e) of the Code), the Board
may, with the consent of the successor corporation and the participant, provide
for the consideration to be received upon exercise of the option to be solely
common stock of the successor corporation or its parent equal in fair market
value to the per share consideration received by holders of Common Stock and the
sale of assets or merger.

      The Board may, if it so determines in the exercise of its sole
discretion, also make provision for adjusting the Reserves, as well as the price
per share of Common Stock covered by each outstanding option, in the event that
the Company effects one or more reorganizations, recapitalizations, rights
offerings or other increases or reductions of shares of its outstanding Common
Stock, and in the event of the Company being consolidated with or merged into
any other corporation.

20.  AMENDMENT OR TERMINATION.

     (a)  The Board of Directors of the Company may at any time terminate or
amend the Plan. Except as provided in SECTION 19, no such termination may affect
options previously granted, nor may an amendment make any change in any option
theretofore granted which adversely affects the rights of any participant. In
addition, to the extent necessary to comply with Rule 16b-3 under the Exchange
Act, or under Section 423 of the Code (or any successor rule or provision or any
applicable law or regulation), the Company shall obtain shareholder approval in
such a manner and to such a degree as so required.

     (b)  Without shareholder consent and without regard to whether any
participant rights may be considered to have been adversely affected, the Board
(or its committee) shall be entitled to change the Offering Periods and Purchase
Periods, limit the frequency and/or number of changes in the amount withheld
during an Offering Period, establish the exchange ratio applicable to amounts
withheld in a currency other than U.S. dollars, permit payroll withholding in
excess of the amount designated by a participant in order to adjust for delays
or mistakes in the Company's processing of properly completed withholding
elections, establish reasonable waiting and adjustment periods and/or accounting
and crediting procedures to ensure that amounts applied toward the purchase of
Common Stock for each participant properly correspond with amounts withheld from
the participant's Compensation, and

                                       7
<PAGE>   9

establish such other limitations or procedures as the Board (or its committee)
Determines in its sole discretion advisable which are consistent with the Plan.

21.  NOTICES. All notices or other communications by a participant to the
Company under or in connection with the Plan shall be deemed to have been duly
given when received in the form specified by the Company at the location, or by
the person, designated by the Company for the receipt thereof.

22.  CONDITIONS UPON ISSUANCE OF SHARES. Shares shall not be issued with respect
to an option unless the exercise of such option and the issuance and delivery of
such shares pursuant thereto shall comply with all applicable provisions of law,
domestic or foreign, including, without limitation, the Securities Act of 1933,
as amended, the Exchange Act, the rules and regulations promulgated under those
Acts, and the requirements of any stock exchange upon which the shares may then
be listed, and shall be further subject to the approval of counsel for the
Company with respect to such compliance. As a condition to the exercise of an
option, the Company may require the person exercising such option to represent
and warrant at the time of any such exercise that the shares are being purchased
only for investment and without any present intention to sell or distribute such
shares if, in the opinion of counsel for the Company, such a representation is
required by any of the aforementioned applicable provisions of law.

23.  TERM OF PLAN; EFFECTIVE DATE. The Plan shall become effective upon the
earlier to occur of its adoption by the Board of Directors or its approval by
the shareholders of the Company. It shall continue in effect for a term of
twenty (20) years unless sooner terminated under SECTION 20.

24.  ADDITIONAL RESTRICTIONS OF RULE 16b-3. The terms and conditions of options
granted hereunder to, and the purchase of shares by, persons subject to Section
16 of the Exchange Act shall comply with the applicable provisions of Rule
16b-3. This Plan shall be deemed to contain, and such options shall contain, and
the shares issued upon exercise thereof shall be subject to, such additional
conditions and restrictions as may be required by Rule 16b-3 to qualify for the
maximum exemption from Section 16 of the Exchange Act with respect to Plan
transactions.

                               * * * * * * * * * *

                                       8
<PAGE>   10

                                     Exhibit
                              CONNETICS CORPORATION
                        1995 EMPLOYEE STOCK PURCHASE PLAN
                             SUBSCRIPTION AGREEMENT

New Election  [ ]                                        Change of Election  [ ]

1.   I, ________________________, hereby elect to participate in the CONNETICS
CORPORATION 1995 Employee Stock Purchase Plan (the "Plan") for the Offering
Period ______________, 20___ to _______________, 20__, and subscribe to purchase
shares of the Company's Common Stock in accordance with this Subscription
Agreement and the Plan.

2.   I elect to have Contributions in the amount of ____% of my Compensation, as
those terms are defined in the Plan, applied to this purchase. I understand that
this amount must not be less than 1% and not more than 15% of my Compensation
during the Offering Period. (PLEASE NOTE THAT NO FRACTIONAL PERCENTAGES ARE
PERMITTED).

3.   I hereby authorize payroll deductions from each paycheck during the
Offering Period at the rate stated in Item 2 of this Subscription Agreement. I
understand that all payroll deductions made by me shall be credited to my
account under the Plan and that I may not make any additional payments into such
account. I understand that all payments made by me shall be accumulated for the
purchase of shares of Common Stock at the applicable purchase price determined
in accordance with the Plan. I further understand that, except as otherwise set
forth in the Plan, shares will be purchased for me automatically on the Purchase
Date of each Offering Period unless I otherwise withdraw from the Plan by giving
written notice to the Company for such purpose.

4.   I understand that I may discontinue at any time prior to the Purchase Date
my participation in the Plan as provided in Section 10 of the Plan. I also
understand that I can decrease the rate of my Contributions on one occasion only
during any Offering Period by completing and filing a new Subscription Agreement
with such decrease taking effect as of the beginning of the calendar quarter
following the date of filing of the new Subscription Agreement. Further, I may
change the rate of deductions for future Offering Periods by filing a new
Subscription Agreement, and any such change will be effective as of the
beginning of the next Offering Period. In addition, I acknowledge that, unless I
discontinue my participation in the Plan as provided in Section 10 of the Plan,
my election will continue to be effective for each successive Offering Period.

5.   I have received a copy of the Company's most recent description of the Plan
and a copy of the complete "CONNETICS CORPORATION 1995 Employee Stock Purchase
Plan." I understand that my participation in the Plan is in all respects subject
to the terms of the Plan.

6.   Shares purchased for me under the Plan should be issued in the name(s) of
(name of employee or employee and spouse only):

                      ------------------------------------

                      ------------------------------------

7.   In the event of my death, I hereby designate the following as my
beneficiary(ies) to receive all payments and shares due to me under the Plan:

                                       9
<PAGE>   11

NAME:
      ---------------------------------------
(Please print) (First)   (Middle)      (Last)

---------------------------------------------
             (Relationship)

-------------------------------------
               (Address)

-------------------------------------

8.   I understand that if I dispose of any shares received by me pursuant to the
Plan within two years after the Offering Date (the first day of the Offering
Period during which I purchased such shares) or within one year after the
Purchase Date, I will be treated for federal income tax purposes as having
received ordinary compensation income at the time of such disposition in an
amount equal to the excess of the fair market value of the shares on the
Purchase Date over the price which I paid for the shares, regardless of whether
I disposed of the shares at a price less than their fair market value at the
Purchase Date. The remainder of the gain or loss, if any, recognized on such
disposition will be treated as capital gain or loss.

          I hereby agree to notify the Company in writing within 30 days after
the date of any such disposition, and I will make adequate provision for
federal, state or other tax withholding obligations, if any, which arise upon
the disposition of the Common Stock. The Company may, but will not be obligated
to, withhold from my compensation the amount necessary to meet any applicable
withholding obligation including any withholding necessary to make available to
the Company any tax deductions or benefits attributable to the sale or early
disposition of Common Stock by me.

9.   If I dispose of such shares at any time after expiration of the 2-year and
1-year holding periods, I understand that I will be treated for federal income
tax purposes as having received compensation income only to the extent of an
amount equal to the lesser of (1) the excess of the fair market value of the
shares at the time of such disposition over the purchase price which I paid for
the shares under the option, or (2) 15% of the fair market value of the shares
on the Offering Date. The remainder of the gain or loss, if any, recognized on
such disposition will be treated as capital gain or loss.

          I understand that this tax summary is only a summary and is subject to
change. I further understand that I should consult a tax advisor concerning the
tax implications of the purchase and sale of stock under the Plan.

10.  I hereby agree to be bound by the terms of the Plan. The effectiveness of
this Subscription Agreement is dependent upon my eligibility to participate in
the Plan.

SIGNATURE:
          -------------------------------

SOCIAL SECURITY #:
                   ------------------------------
DATE:
     ----------------------

SPOUSE'S SIGNATURE (necessary if beneficiary is not spouse):

-----------------------------------------
(Signature)

-----------------------------------------
(Print name)

                                     ******

                                       10
<PAGE>   12

                                     Exhibit
                              CONNETICS CORPORATION
                        1995 EMPLOYEE STOCK PURCHASE PLAN
                              NOTICE OF WITHDRAWAL

I, __________________________, hereby elect to withdraw my participation in the
CONNETICS CORPORATION 1995 Employee Stock Purchase Plan (the "Plan") for the
Offering Period ______________, 20___ to _______________, 20__. This withdrawal
covers all Contributions credited to my account and is effective on the date
designated below.

I understand that all Contributions credited to my account will be paid to me
within ten (10) business days of receipt by the Company of this Notice of
Withdrawal and that my option for the current period will automatically
terminate, and that no further Contributions for the purchase of shares can be
made by me during the Offering Period.

I further understand and agree that I shall be eligible to participate in
succeeding Offering Periods only by delivering to the Company a new Subscription
Agreement.

If the undersigned is an Officer or Director of CONNETICS CORPORATION or other
person subject to Section 16 of the Securities Exchange Act of 1934, the
signature below indicates that, in addition to the foregoing, I understand that
under rules promulgated by the U.S. Securities and Exchange Commission I may not
re-enroll in the Plan for a period of six (6) months after withdrawal.

Dated:
      ------------------------------
        Signature of Employee

-------------------------------------
    Social Security Number

                                     ******

                                       11<PAGE>   1
                                                                     EXHIBIT 4.3

                              CONNETICS CORPORATION
                      2000 NON-OFFICER EMPLOYEE STOCK PLAN
                           (ADOPTED FEBRUARY 17, 2000)

     1.   PURPOSES OF THE PLAN. The purposes of this 2000 Non-Officer Employee
Stock Plan ("PLAN") are to attract and retain the best available personnel for
positions of substantial responsibility, to provide additional incentive to
Employees and Consultants of the Company and its Subsidiaries and to promote the
success of the Company's business. Options granted under the Plan may be
Nonstatutory Stock Options, as determined by the Administrator at the time of
grant and reflected in the terms of the written option agreement. Stock purchase
rights may also be granted under the Plan.

     2.   DEFINITIONS. As used in this Plan, the following definitions shall
apply:

          (a)  "Administrator" means the Board or any of its Committees
     appointed pursuant to Section 4 of the Plan.

          (b)  "Board" means the Board of Directors of the Company.

          (c)  "Code" means the Internal Revenue Code of 1986, as amended.

          (d)  "Committee" means the Committee appointed by the Board of
     Directors in accordance with SECTION 4(a) of the Plan below, if one is
     appointed.

          (e)  "Common Stock" means the Common Stock of the Company.

          (f)  "Company" means Connetics Corporation, a Delaware corporation.

          (g)  "Consultant" means any person, including an advisor, who is
     engaged by the Company or any Parent or Subsidiary to render services and
     is compensated for such services, and any director of the Company, whether
     compensated for such services or not.

          (h)  "Continuous Status as an Employee or Consultant" means the
     absence of any interruption or termination of service as an Employee or
     Consultant. Continuous Status as an Employee or Consultant shall not be
     considered interrupted in the case of sick leave, military leave, or any
     other leave of absence approved by the Administrator, provided that such
     leave is for a period of not more than ninety (90) days, unless
     reemployment upon the expiration of such leave is guaranteed by contract or
     statute, or unless provided otherwise pursuant to Company policy adopted
     from time to time, or in the case of transfers between locations of the
     Company or between the Company, its Subsidiaries or its successor. For
     purposes of this Plan, a change in status from an Employee to a Consultant
     or from a Consultant to an Employee will not constitute a termination of
     employment.

          (i)  "Director" means a member of the Board.

          (j)  "Employee" means any person, excluding Named Executives, Officers
     and Directors, employed by the Company or any Parent or Subsidiary of the
     Company.

          (k)  "Exchange Act" means the Securities Exchange Act of 1934, as
     amended.

<PAGE>   2

          (l)  "Fair Market Value" means, as of any date, the value of Common
     Stock determined as follows:

               (i)  If the Common Stock is listed on any established stock
          exchange or a national market system including without limitation the
          National Market of the National Association of Securities Dealers,
          Inc. Automated Quotation ("Nasdaq") System, its Fair Market Value
          shall be the closing sales price for such stock as quoted on such
          system on the date of determination (or the closing bid, if no sales
          were reported on that day) as reported in The Wall Street Journal or
          such other source as the Administrator deems reliable;

               (ii) If the Common Stock is quoted on the Nasdaq System (but not
          on the National Market thereof) or regularly quoted by a recognized
          securities dealer but selling prices are not reported, its Fair Market
          Value shall be the mean between the high bid and low asked prices for
          the Common Stock or;

               (iii) In the absence of an established market for the Common
          Stock, the Fair Market Value thereof shall be determined in good faith
          by the Administrator.

          (m)  "Incentive Stock Option" means an Option intended to qualify as
     an incentive stock option within the meaning of Section 422 of the Code, as
     designated in the applicable written option agreement.

          (n)  "Named Executive" means any individual who, on the last day of
     the Company's fiscal year, is the chief executive officer of the Company
     (or is acting in such capacity) or among the four highest compensated
     officers of the Company (other than the chief executive officer). Such
     officer status shall be determined pursuant to the executive compensation
     disclosure rules under the Exchange Act.

          (o)  "Nonstatutory Stock Option" means an Option not intended to
     qualify as an Incentive Stock Option, as designated in the applicable
     written option agreement.

          (p)  "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.

          (q)  "Option" means a stock option granted pursuant to the Plan.

          (r)  "Optioned Stock" means the Common Stock subject to an Option or a
     Stock Purchase Right.

          (s)  "Optionee" means an Employee or Consultant who receives an Option
     or Stock Purchase Right.

          (t)  "Parent" means a "parent corporation," whether now or hereafter
     existing, as defined in Section 424(e) of the Code.

          (u)  "Restricted Stock" means shares of Common Stock acquired pursuant
     to a grant of a Stock Purchase Right under SECTION 11 below.

          (v)  "Rule 16b-3" means Rule 16b-3 promulgated under the Exchange Act
     as the same may

                                       2
<PAGE>   3

     be amended from time to time, as any successor provision.

          (w)  "Share" means a share of the Common Stock, as adjusted in
     accordance with SECTION 13 below.

          (x)  "Stock Purchase Right" means the right to purchase Common Stock
     pursuant to SECTION 11 below.

          (y)  "Subsidiary" means a "subsidiary corporation," whether now or
     hereafter existing, as defined in Section 424(f) of the Code.

          (z)  "Plan" means this 2000 Non-Officer Employee Stock Plan.

          3.   STOCK SUBJECT TO THE PLAN. Subject to the provisions of SECTION
     13, the maximum aggregate number of shares which may be optioned and sold
     under the Plan is 500,000 shares of Common Stock. The shares may be
     authorized, but unissued, or reacquired Common Stock. If an Option should
     expire or become unexercisable for any reason without having been exercised
     in full, the unpurchased Shares which were subject thereto shall, unless
     the Plan shall have been terminated, become available for future grant
     under the Plan. Notwithstanding any other provision of the Plan, Shares
     issued under the Plan and later repurchased by the Company shall not become
     available for future grant or sale under the Plan.

          4.   ADMINISTRATION OF THE PLAN.

               (a)  Composition of the Administrator.

                    (i)  Administration of the Plan. With respect to grants of
               Options or Stock Purchase Rights to Employees or Consultants who
               are neither Directors nor Officers of the Company, the Plan shall
               be administered by (A) the Board or (B) a committee designated by
               the Board, which committee shall be constituted in such a manner
               as to satisfy the legal requirements relating to the
               administration of stock option plans, if any, of the applicable
               securities laws and the Code (collectively the "Applicable
               Laws").

                    (ii) General. If a Committee has been appointed pursuant to
               subsection (i) of this SECTION 4(a), such Committee shall
               continue to serve in its designated capacity until otherwise
               directed by the Board. From time to time the Board may increase
               the size of the Committee and appoint additional members thereof,
               remove members (with or without cause) and appoint new members in
               substitution therefor, fill vacancies, however caused, and remove
               all members of the Committee and thereafter directly administer
               the Plan, all to the extent permitted by the Applicable Laws.

               (b)  Powers of the Administrator. Subject to the provisions of
          the Plan and in the case of a Committee, the specific duties delegated
          by the Board to such Committee, and subject to the approval of any
          relevant authorities, including the approval, if required, of any
          stock exchange upon which the Common Stock is listed, the
          Administrator shall have the authority, in its discretion:

                    (i)  to determine the Fair Market Value of the Common Stock,
                in accordance with SECTION 2(l) of the Plan;

                                       3
<PAGE>   4

                    (ii) to select the Consultants and Employees to whom Options
               and Stock Purchase Rights may from time to time be granted
               hereunder;

                    (iii) to determine whether and to what extent Options and
               Stock Purchase Rights or any combination thereof are granted
               hereunder;

                    (iv) to determine the number of shares of Common Stock to be
               covered by each such award granted hereunder;

                    (v)  to approve forms of agreement for use under the Plan;

                    (vi) to determine the terms and conditions, not inconsistent
               with the terms of the Plan, of any award granted hereunder;

                    (vii) to determine whether and under what circumstances an
               Option may be settled in cash under SUBSECTION 10(f) instead of
               Common Stock;

                    (viii) to reduce the exercise price of any Option to the
               then current Fair Market Value if the Fair Market Value of the
               Common Stock covered by such Option shall have declined since the
               date the Option was granted; and

                    (ix) to determine the terms and restrictions applicable to
               Stock Purchase Rights and the Restricted Stock purchased by
               exercising such Stock Purchase Rights.

          (c)  Effect of Administrator's Decision. All decisions, determinations
     and interpretations of the Administrator shall be final and binding on all
     Optionees and any other holders of any Options or Stock Purchase Rights.

     5.   ELIGIBILITY.

          (a)  Nonstatutory Stock Options and Stock Purchase Rights may be
     granted to Employees and Consultants. An Employee or Consultant who has
     been granted an Option or Stock Purchase Right may, if he is otherwise
     eligible, be granted additional Options or Stock Purchase Rights.

          (b)  Each Option shall be designated in the written option agreement
     as a Nonstatutory Stock Option.

          (c)  The Plan shall not confer upon any Optionee any right with
     respect to continuation of employment or consulting relationship with the
     Company, nor shall it interfere in any way with his or her right or the
     Company's right to terminate his or her employment or consulting
     relationship at any time, with or without cause.

     6.   TERM OF PLAN. The Plan shall become effective upon its adoption by the
Board of Directors. It shall continue in effect for a term of ten (10) years
unless sooner terminated under SECTION 17 of the Plan.

     7.   TERM OF OPTION. The term of each Option shall be the term stated in
the Option Agreement; provided, however, that in the case of an Option granted
to an Optionee who, at the time the Option is granted, owns stock representing
more than ten percent (10%) of the voting power of all classes of stock of the
Company or any Parent or Subsidiary, the term of the Option shall be five (5)
years from

                                       4
<PAGE>   5

the date of grant thereof or such shorter term as may be provided in the Option
Agreement.

     8.   LIMITATION ON GRANTS TO EMPLOYEES. Subject to adjustment as provided
in this Plan, the maximum number of Shares which may be subject to Options or
Stock Purchase Rights granted to any one Employee under this Plan for any fiscal
year of the Company shall be 150,000.

     9.   OPTION EXERCISE PRICE AND CONSIDERATION.

          (a)  The per Share exercise price for the Shares to be issued pursuant
     to exercise of an Option shall be such price as is determined by the
     Administrator, but shall in any event be no less than 100% of the Fair
     Market Value per Share on the date of grant.

          (b)  The consideration to be paid for the Shares to be issued upon
     exercise of an Option, including the method of payment, shall be determined
     by the Administrator and may consist entirely of

               (1)  cash,

               (2)  check,

               (3)  promissory note,

               (4)  other Shares which (x) in the case of Shares acquired upon
                    exercise of an Option either have been owned by the Optionee
                    for more than six months on the date of surrender or were
                    not acquired, directly or indirectly, from the Company, and
                    (y) have a Fair Market Value on the date of surrender equal
                    to the aggregate exercise price of the Shares as to which
                    said Option shall be exercised,

               (5)  authorization from the Company to retain from the total
                    number of Shares as to which the Option is exercised that
                    number of Shares having a Fair Market Value on the date of
                    exercise equal to the exercise price for the total number of
                    Shares as to which the Option is exercised,

               (6)  delivery of a properly executed exercise notice together
                    with such other documentation as the Administrator and the
                    broker, if applicable, shall require to effect an exercise
                    of the Option and delivery to the Company of the sale or
                    loan proceeds required to pay the exercise price,

               (7)  any combination of the foregoing methods of payment, or

               (8)  such other consideration and method of payment for the
                    issuance of Shares to the extent permitted under Applicable
                    Laws.

In making its determination as to the type of consideration to accept, the Board
shall consider if acceptance of such consideration may be reasonably expected to
benefit the Company.

     10.  EXERCISE OF OPTION.

          (a)  Procedure for Exercise; Rights as a Stockholder. Any Option
     granted under this Plan shall be exercisable at such times and under such
     conditions as the Administrator

                                       5
<PAGE>   6

     determines, including performance criteria with respect to the Company
     and/or the Optionee, and as shall be permissible under the terms of the
     Plan. An Option may not be exercised for a fraction of a Share. An Option
     shall be deemed to be exercised when written notice of such exercise has
     been given to the Company in accordance with the terms of the Option by the
     person entitled to exercise the Option and full payment for the Shares with
     respect to which the Option is exercised has been received by the Company.
     Full payment may, as authorized by the Administrator, consist of any
     consideration and method of payment allowable under SECTION 9(b) of the
     Plan. Until the issuance (as evidenced by the appropriate entry on the
     books of the Company or of a duly authorized transfer agent of the Company)
     of the stock certificate evidencing such Shares, no right to vote or
     receive dividends or any other rights as a stockholder shall exist with
     respect to the Optioned Stock, notwithstanding the exercise of the Option.
     The Company shall issue (or cause to be issued) such stock certificate as
     promptly as practicable upon exercise of the Option. No adjustment will be
     made for a dividend or other right for which the record date is prior to
     the date the stock certificate is issued, except as provided in SECTION 14
     of the Plan.

          Exercise of an Option in any manner shall result in a decrease in the
     number of Shares which thereafter may be available, both for purposes of
     the Plan and for sale under the Option, by the number of Shares as to which
     the Option is exercised.

          (b)  Termination of Status as an Employee or Consultant. In the event
     of termination of an Optionee's Continuous Status as an Employee or
     Consultant, such Optionee may, but only within thirty (30) days (or such
     other period of time not exceeding six (6) months as is determined by the
     Administrator) after the date of such termination (but in no event later
     than the date of expiration of the term of such Option as set forth in the
     Option Agreement), exercise his or her Option to the extent that he or she
     was entitled to exercise it at the date of such termination. To the extent
     that the Optionee was not entitled to exercise the Option at the date of
     such termination, or if the optionee does not exercise such Option (which
     he or she was entitled to exercise) within the time specified herein, the
     Option shall terminate.

          (c)  Disability of Optionee.

               (i)  Notwithstanding the provisions of SECTION 9(b) above, in the
          event of termination of an Optionee's Continuous Status as an Employee
          or Consultant as a result of his or her total and permanent disability
          (within the meaning of Section 22(e)(3) of the Code), Optionee may,
          but only within twelve (12) months from the date of such termination
          (but in no event later than the expiration date of the term of such
          Option as set forth in the Option Agreement), exercise the Option to
          the extent otherwise entitled to exercise it at the date of such
          termination. To the extent that Optionee was not entitled to exercise
          the Option at the date of termination, or if Optionee does not
          exercise such Option to the extent so entitled within the time
          specified herein, the Option shall terminate.

               (ii) In the event of termination of an Optionee's Continuous
          Status as an Employee or Consultant as a result of a disability which
          does not fall within the meaning of total and permanent disability (as
          set forth in Section 22(e)(3) of the Code), Optionee may, but only
          within six (6) months from the date of such termination (but in no
          event later than the expiration date of the term of such Option as set
          forth in the Option Agreement), exercise the Option to the extent
          otherwise entitled to exercise it at the date of such termination. To
          the extent that Optionee was not entitled to exercise the Option at
          the date of termination, or if

                                       6
<PAGE>   7

          Optionee does not exercise such Option to the extent so entitled
          within six months (6) from the date of termination, the Option shall
          terminate.

          (d)  Death of Optionee. In the event of the death of an Optionee
     during the term of the Option who is at the time of death an Employee or
     Consultant of the Company, the Option may be exercised, at any time within
     twelve (12) months following the date of death (but in no event later than
     the expiration date of the term of such Option as set forth in the Option
     Agreement), by the Optionee's estate or by a person who acquired the right
     to exercise the Option by bequest or inheritance, but only to the extent
     the Optionee was entitled to exercise the Option at the date of death. To
     the extent that Optionee was not entitled to exercise the Option at the
     date of termination, or if Optionee does not exercise such Option to the
     extent so entitled within the time specified herein, the Option shall
     terminate.

          (e)  Rule 16b-3. Options granted to persons subject to Section 16(b)
     of the Exchange Act must comply with Rule 16b-3 and shall contain such
     additional conditions or restrictions as may be required thereunder to
     qualify for the maximum exemption from Section 16 of the Exchange Act with
     respect to Plan transactions.

          (f)  Buyout Provisions. The Administrator may at any time offer to buy
     out for a payment in cash or Shares, an Option previously granted, based on
     such terms and conditions as the Administrator shall establish and
     communicate to the Optionee at the time that such offer is made.

     11.  NON-TRANSFERABILITY OF OPTIONS. Option may not be sold, pledged,
assigned, hypothecated, transferred, or disposed of in any manner other than by
will or by the laws of descent or distribution and may be exercised, during the
lifetime of the Optionee, only by the Optionee.

     12.  STOCK PURCHASE RIGHTS.

          (a)  Rights to Purchase. Stock Purchase Rights may be issued either
     alone, in addition to, or in tandem with other awards granted under the
     Plan and/or cash awards made outside of the Plan. After the Administrator
     determines that it will offer Stock Purchase Rights under the Plan, it
     shall advise the offeree in writing of the terms, conditions and
     restrictions related to the offer, including the number of Shares that such
     person shall be entitled to purchase, the price to be paid (which price
     shall not be less than 85% of the Fair Market Value of the Shares as of the
     date of the offer or, in the case of a stockholder owning ten percent (10%)
     or more of the Company's outstanding stock or a person who is a Named
     Executive, 100% of the Fair Market Value of the Shares as of the date of
     the offer), and the time within which such person must accept such offer,
     which shall in no event exceed thirty (30) days from the date upon which
     the Administrator made the determination to grant the Stock Purchase Right.
     The offer shall be accepted by execution of a Restricted Stock purchase
     agreement in the form determined by the Administrator. Shares purchased
     pursuant to the grant of a Stock Purchase Right shall be referred to herein
     as "Restricted Stock."

          (b)  Repurchase Option. Unless the Administrator determines otherwise,
     the Restricted Stock purchase agreement shall grant the Company a
     repurchase option exercisable upon the voluntary or involuntary termination
     of the purchaser's employment with the Company for any reason (including
     death or Disability). The purchase price for Shares repurchased pursuant to
     the Restricted Stock purchase agreement shall be the original price paid by
     the purchaser and may be paid by cancellation of any indebtedness of the
     purchaser to the Company. The repurchase option shall lapse at such rate as
     the Board or Committee may determine.

                                       7
<PAGE>   8

          (c)  Other Provisions. The Restricted Stock purchase agreement shall
     contain such other terms, provisions and conditions not inconsistent with
     the Plan as may be determined by the Administrator in its sole discretion.
     In addition, the provisions of Restricted Stock purchase agreements need
     not be the same with respect to each purchaser.

          (d)  Rights as a Stockholder. Once the Stock Purchase Right is
     exercised, the purchaser shall have the rights equivalent to those of a
     stockholder, and shall be a stockholder when his or her purchase is entered
     upon the records of the duly authorized transfer agent of the Company. No
     adjustment will be made for a dividend or other right for which the record
     date is prior to the date the Stock Purchase Right is exercised, except as
     provided in SECTION 15 of the Plan.

     13.  WITHHOLDING TAXES. As a condition to the exercise of Options or the
purchase of Restricted Stock pursuant to awards granted hereunder, the Optionee
or purchaser shall make such arrangements as the Administrator may require for
the satisfaction of any federal, state, local or foreign withholding tax
obligations that may arise in connection with the exercise, receipt or vesting
of such award. The Company shall not be required to issue any Shares under the
Plan until such obligations are satisfied.

     14.  STOCK WITHHOLDING TO SATISFY WITHHOLDING TAX OBLIGATIONS. At the
Administrator's discretion, Optionees may satisfy withholding obligations as
provided in this paragraph. When an Optionee incurs tax liability in connection
with an Option or Stock Purchase Right, which tax liability is subject to tax
withholding under applicable tax laws, and the Optionee is obligated to pay the
Company an amount required to be withheld under applicable tax laws, the
Optionee may satisfy the withholding tax obligation by electing to have the
Company withhold from the Shares to be issued upon exercise of the Option, or
the Shares to be issued in connection with the Stock Purchase Right, if any,
that number of Shares having a Fair Market Value equal to the amount required to
be withheld. The Fair Market Value of the Shares to be withheld shall be
determined on the date that the amount of tax to be withheld is to be determined
(the "TAX DATE"). All elections by an Optionee to have Shares withheld for this
purpose shall be made in writing in a form acceptable to the Administrator and
shall be subject to the following restrictions:

          (a)  the election must be made on or prior to the applicable Tax Date;

          (b)  once made, the election shall be irrevocable as to the particular
     Shares of the Option or Stock Purchase Right as to which the election is
     made; and

          (c)  all elections shall be subject to the consent or disapproval of
     the Administrator.

     In the event the election to have Shares withheld is made by an
Optionee and the Tax Date is deferred under Section 83 of the Code because no
election is filed under Section 83(b) of the Code, the Optionee shall receive
the full number of Shares with respect to which the Option or Stock Purchase
Right is exercised but such Optionee shall be unconditionally obligated to
tender back to the Company the proper number of Shares on the Tax Date.

     15.  ADJUSTMENTS UPON CHANGES IN CAPITALIZATION; CORPORATE TRANSACTION.

          (a)  Changes in Capitalization. Subject to any required action by the
     stockholders of the Company, the number of shares of Common Stock covered
     by each outstanding Option or Stock Purchase Right, and the number of
     shares of Common Stock which have been authorized

                                       8
<PAGE>   9

     for issuance under the Plan but as to which no Options or Stock Purchase
     Rights have yet been granted or which have been returned to the Plan upon
     cancellation or expiration of an Option or Stock Purchase Right, as well as
     the price per share of Common Stock covered by each such outstanding Option
     or Stock Purchase Right, shall be proportionately adjusted for any increase
     or decrease in the number of issued shares of Common Stock resulting from a
     stock split, reverse stock split, stock dividend, combination or
     reclassification of the Common Stock, or any other increase or decrease in
     the number of issued shares of Common Stock effected without receipt of
     consideration by the Company; provided, however, that conversion of any
     convertible securities of the Company shall not be deemed to have been
     "effected without receipt of consideration." Such adjustment shall be made
     by the Board, whose determination in that respect shall be final, binding
     and conclusive. Except as expressly provided herein, no issuance by the
     Company of shares of stock of any class, or securities convertible into
     shares of stock of any class, shall affect, and no adjustment by reason
     thereof shall be made with respect to, the number or price of shares of
     Common Stock subject to an Option or Stock Purchase Right.

          (b)  Corporate Transactions. In the event of a dissolution or
     liquidation of the Company, the Option will terminate immediately prior to
     the consummation of such action, unless otherwise provided by the
     Administrator. The Administrator may, in the exercise of its sole
     discretion in such instances, declare that any Option shall terminate as of
     a date fixed by the Administrator and give each Optionee the right to
     exercise his or her Option as to all of the Optioned Stock, including
     Shares as to which the Option would not otherwise be exercisable. In the
     event of a proposed sale of all or substantially all of the assets of the
     Company, the merger of the Company with or into another corporation or any
     other capital reorganization in which more than fifty percent (50%) of the
     shares of the Company entitled to vote are exchanged, the Option shall be
     assumed or an equivalent option shall be substituted by such successor
     corporation or a parent or subsidiary of such successor corporation, unless
     the Administrator determines, in the exercise of its sole discretion and in
     lieu of such assumption or substitution, that the Optionee shall have the
     right to exercise the Option as to all of the Optioned Stock, including
     Shares as to which the Option would not otherwise be exercisable. If the
     Administrator makes an Option exercisable in lieu of assumption or
     substitution in the event of a merger or sale of assets, the Administrator
     shall notify the Optionee that the Option shall be exercisable for a period
     of thirty (30) days from the date of such notice, and the Option will
     terminate upon the expiration of such period.

     16.  TIME OF GRANTING OPTIONS AND STOCK PURCHASE RIGHTS. The date of grant
of an Option or Stock Purchase Right shall, for all purposes, be the date on
which the Administrator makes the determination granting such Option or Stock
Purchase Right, or such other date as is determined by the Administrator;
provided however that in the case of any Incentive Stock Option, the grant date
shall be the later of the date on which the Administrator makes the
determination granting such Incentive Stock Option or the date of commencement
of the Optionee's employment relationship with the Company. Notice of the
determination shall be given to each Employee or Consultant to whom an Option or
Stock Purchase Right is so granted within a reasonable time after the date of
such grant.

     17.  AMENDMENT AND TERMINATION OF THE PLAN.

          (a)  Amendment and Termination. The Board may amend or terminate the
     Plan from time to time in such respects as the Board may deem advisable;
     provided, however, that the following revisions or amendments shall require
     approval of the stockholders of the Company:

               (i)  any change in the designation of the class of persons
          eligible to be granted Options;

                                       9
<PAGE>   10

               (ii) any change in the limitation on grants to employees as
          described in SECTION 8 of the Plan or other changes which would
          require stockholder approval to qualify options granted hereunder as
          performance-based compensation under Section 162(m) of the Code; or

               (iii) any revision or amendment requiring stockholder approval in
          order to preserve the qualification of the Plan under Rule 16b-3.

          (b)  Effect of Amendment or Termination. Any such amendment or
     termination of the Plan shall not affect Options already granted and such
     Options shall remain in full force and effect as if this Plan had not been
     amended or terminated, unless mutually agreed otherwise between the
     Optionee and the Board, which agreement must be in writing and signed by
     the Optionee and the Company.

     18.  CONDITIONS UPON ISSUANCE OF SHARES. Shares shall not be issued
pursuant to the exercise of an Option or Stock Purchase Right unless the
exercise of such Option and the issuance and delivery of such Shares pursuant
thereto shall comply with all relevant provisions of law, including, without
limitation, the Securities Act of 1933, as amended, the Exchange Act, the rules
and regulations promulgated thereunder, and the requirements of any stock
exchange upon which the Shares may then be listed, and shall be further subject
to the approval of counsel for the Company with respect to such compliance. As a
condition to the exercise of an Option or Stock Purchase Right, the Company may
require the person exercising such Option or Stock Purchase Right to represent
and warrant at the time of any such exercise that the Shares are being purchased
only for investment and without any present intention to sell or distribute such
Shares if, in the opinion of counsel for the Company, such a representation is
required by any of the aforementioned relevant provisions of law.

     19.  RESERVATION OF SHARES. The Company, during the term of this Plan, will
at all times reserve and keep available such number of Shares as shall be
sufficient to satisfy the requirements of the Plan. The inability of the Company
to obtain authority from any regulatory body having jurisdiction, which
authority is deemed by the Company's counsel to be necessary to the lawful
issuance and sale of any Shares hereunder, shall relieve the Company of any
liability in respect of the failure to issue or sell such Shares as to which
such requisite authority shall not have been obtained.

     20.  AGREEMENTS. Options and Stock Purchase Rights shall be evidenced by
written agreements in such form as the Board shall approve from time to time.

     21.  INFORMATION TO OPTIONEES AND PURCHASERS. The Company shall provide
financial statements at least annually to each Optionee and to each individual
who acquired Shares Pursuant to the Plan, during the period such Optionee or
purchaser has one or more Options or Stock Purchase Rights outstanding, and in
the case of an individual who acquired Shares pursuant to the Plan, during the
period such individual owns such Shares. The Company shall not be required to
provide such information if the issuance of Options or Stock Purchase Rights
under the Plan is limited to key employees whose duties in connection with the
Company assure their access to equivalent information.

                                     ******

                                       10
<PAGE>   11
                                     Exhibit
                              CONNETICS CORPORATION
                      2000 NON-OFFICER EMPLOYEE STOCK PLAN
                             STOCK OPTION AGREEMENT

                   OPTIONEE:        <<firstname>> <<middle>> <<lastname>>
                   GRANT NUMBER:    <<grantnumber>>

     1.   Grant of Option. Connetics Corporation, a Delaware corporation
("CONNETICS"), hereby grants to the Optionee (the "OPTIONEE") named in the
attached Notice of Stock Option Grant (the "NOTICE"), an option (the "OPTION")
to purchase a total number of shares of Common Stock (the "SHARES") set forth in
the Notice, at the Exercise Price Per Share set forth in the Notice subject to
the terms, definitions and provisions of Connetics' 2000 Non-Officer Employee
Stock Plan (the "PLAN") adopted by Connetics, which is incorporated into this
Agreement by reference. Unless otherwise defined in this Agreement, the terms
defined in the Plan shall have the same defined meanings as applied to this
Option.

     2.   Exercise of Option. This Option shall be exercisable during its term
in accordance with the Vesting Schedule set out in the Notice and with the
provisions of Section 9 of the Plan as follows:

          (i)  Right to Exercise.

               (a)  This Option may not be exercised for a fraction of a share.

               (b)  In the event of Optionee's death or disability, or other
termination of Optionee's consulting relationship or employment ("CONTINUOUS
STATUS"), the exercisability of the Option is governed by SECTIONS 5, 6 and 7
below, subject to the limitation contained in SUBSECTION 2(i)(c).

               (c)  In no event may this Option be exercised after the date of
expiration of the Term of this Option as set forth in the Notice.

          (ii) Method of Exercise. This Option shall be exercisable by written
notice which shall state the election to exercise the Option, the number of
shares of Common Stock in respect of which the Option is being exercised (the
"Shares Exercised"), and such other representations and agreements as to the
Optionee's investment intent with respect to such Shares Exercised as may be
required by Connetics pursuant to the provisions of the Plan. Such written
notice shall be signed by the Optionee and shall be delivered in person or by
certified mail to the Secretary or Assistant Secretary of Connetics. The written
notice shall be accompanied by payment in the amount of the Shares Exercised
times the Exercise Price Per Share (the "EXERCISE PRICE"). Exercise of this
Option shall be deemed to be effective (the "EFFECTIVE DATE") upon receipt by
Connetics of such written notice accompanied by the Exercise Price. No stock
certificate will be issued pursuant to the exercise of an Option unless such
issuance and such exercise comply with all relevant provisions of law and the
requirements of any stock exchange upon which the Shares may then be listed.
Assuming such compliance, the Shares Exercised shall be considered for income
tax purposes to have been issued to the Optionee on the Effective Date on which
the Option was exercised with respect to those Shares.

     3.   Method of Payment. Payment of the Exercise Price shall be by any of
the following, or a combination of one or more of the following, at the
Optionee's election:

                                       11
<PAGE>   12

               (a)  cash; or

               (b)  check; or

               (c)  surrender of other shares of Connetics Common Stock which
          (A) in the case of Shares acquired pursuant to the exercise of a
          Connetics option, the Optionee has owned for more than six (6) months
          on the date of surrender, and (B) have a fair market value on the date
          of surrender equal to the Exercise Price; or

               (d)  delivery of a properly executed exercise notice together
          with such other documentation as the Administrator of the Plan and any
          broker assisting in such exercise, if applicable, shall require to
          effect an exercise of the Option and delivery to Connetics of the sale
          or loan proceeds required to pay the exercise price.

     4.   Restrictions on Exercise. This Option may not be exercised if the
issuance of such Shares upon such exercise or the method of payment of
consideration for such shares would constitute a violation of any applicable
federal or state securities or other law or regulation, including any rule under
Part 207 of Title 12 of the Code of Federal Regulations ("REGULATION G") as
promulgated by the Federal Reserve Board. As a condition to the exercise of this
Option, Connetics may require Optionee to make any representation and warranty
to Connetics as may be required by any applicable law or regulation.

     5.   Termination of Relationship. In the event of termination of Optionee's
Continuous Status, Optionee may, to the extent otherwise so entitled at the date
of such termination (the "TERMINATION DATE"), exercise this Option during the
Termination Period set out in the Notice of Grant. To the extent that Optionee
was not entitled to exercise this Option at the date of such termination, or if
Optionee does not exercise this Option within the time specified herein, the
Option shall terminate.

     6.   Disability of Optionee.

          (a)  Notwithstanding the provisions of SECTION 5 above, in the event
     of termination of Optionee's Continuous Status as a result of his or her
     total and permanent disability (within the meaning of Section 22(e)(3) of
     the Code), Optionee may, but only within twelve (12) months from the date
     of such termination (but in no event later than the Expiration Date of the
     Term of such Option as set forth in Section 9 below), exercise the Option
     to the extent otherwise entitled to exercise it at the date of such
     termination. To the extent that Optionee was not entitled to exercise the
     Option at such date of termination, or if Optionee does not exercise such
     Option to the extent so entitled within the time specified herein, the
     Option shall terminate.

          (b)  In the event of termination of an Optionee's Continuous Status as
     a result of a disability which does not fall within the meaning of total
     and permanent disability (as set forth in Section 22(e)(3) of the Code),
     Optionee may, but only within six (6) months from the date of such
     termination (but in no event later than the Expiration Date of the Term of
     such Option as set forth in SECTION 9 below), exercise the Option to the
     extent otherwise entitled to exercise it at the date of such termination.
     To the extent that Optionee was not entitled to exercise the Option at such
     date of termination, or if Optionee does not exercise such Option to the
     extent so entitled within six months (6) from such date of termination, the
     Option shall terminate.

     7.   Death of Optionee. In the event of the death of Optionee, the Option
may be exercised at any time within twelve (12) months following the date of
death (but in no event later than the Expiration Date of the Term of this Option
as set forth in SECTION 9 below), by Optionee's estate or by a person who
acquired the right to exercise the Option by bequest or inheritance, but only to
the extent the Optionee could exercise the Option at the date of death.

                                       12
<PAGE>   13

     8.   Non-Transferability of Option. This Option may not be transferred in
any manner otherwise than by will or by the laws of descent or distribution and
may be exercised during the lifetime of Optionee only by Optionee. The terms of
this Option shall be binding upon the executors, administrators, heirs,
successors and assigns of the Optionee.

     9.   Term of Option. This Option may be exercised only within the Term set
out in the Notice, and may be exercised during such term only in accordance with
the Plan and the terms of this Option. The limitations set out in Section 7 of
the Plan regarding Options granted to more than ten percent (10%) stockholders
shall apply to this Option.

     10.  Taxation Upon Exercise of Option.

          10.1. Optionee understands that, upon exercising a nonstatutory
Option, he or she will recognize income for tax purposes in an amount equal to
the excess of the then fair market value of the Shares over the exercise price.
If the Optionee is an employee, Connetics will be required to withhold from
Optionee's compensation, or collect from Optionee and pay to the applicable
taxing authorities, an amount equal to a percentage of this compensation income.

          10.2 The Optionee shall satisfy his or her tax withholding obligation
arising upon the exercise of this Option by one or some combination of the
following methods:

          (a)  by cash payment, or

          (b)  out of Optionee's current compensation, or

          (c)  if permitted by the Administrator, in its discretion, by
     surrendering to Connetics Shares which (a) in the case of Shares previously
     acquired from Connetics, have been owned by the Optionee for more than six
     months on the date of surrender, and (b) have a fair market value on the
     date of surrender equal to or less than Optionee's marginal tax rate times
     the ordinary income recognized; or

          (d)  by electing to have Connetics withhold from the Shares to be
     issued upon exercise of the Option that number of Shares having a fair
     market value equal to the amount required to be withheld. For this purpose,
     the fair market value of the Shares to be withheld shall be determined on
     the date that the amount of tax to be withheld is to be determined (the
     "TAX DATE").

          10.3. If the Optionee is subject to Section 16 of the Exchange Act (an
"INSIDER"), any surrender of previously owned Shares to satisfy tax withholding
obligations arising upon exercise of this Option must comply with the applicable
provisions of Rule 16b-3 promulgated under the Exchange Act ("RULE 16b-3") and
shall be subject to such additional conditions or restrictions as may be
required thereunder to qualify for the maximum exemption from Section 16 of the
Exchange Act with respect to Plan transactions.

          10.4. All elections by an Optionee to have Shares withheld to satisfy
tax withholding obligations shall be made in writing in a form acceptable to the
Administrator and shall be subject to the following restrictions:

          (a)  the election must be made on or prior to the applicable Tax Date;

          (b)  once made, the election shall be irrevocable as to the particular
     Shares of the

                                       13
<PAGE>   14

     Option as to which the election is made;

          (c)  all elections shall be subject to the consent or disapproval of
     the Administrator;

          (d)  if the Optionee is an Insider, the election must comply with the
     applicable provisions of Rule 16b-3 and shall be subject to such additional
     conditions or restrictions as may be required thereunder to qualify for the
     maximum exemption from Section 16 of the Exchange Act with respect to Plan
     transactions.

     11.  Tax Consequences. Set forth below is a brief summary as of the date of
this Option of some of the federal and California tax consequences of exercise
of this Option and disposition of the Shares. THIS SUMMARY IS NECESSARILY
INCOMPLETE, AND THE TAX LAWS AND REGULATIONS ARE SUBJECT TO CHANGE. OPTIONEE
SHOULD CONSULT A TAX ADVISER BEFORE EXERCISING THIS OPTION OR DISPOSING OF THE
SHARES.

          (a)  Exercise of Nonstatutory Stock Option. There may be a regular
     federal income tax liability and a California income tax liability upon the
     exercise of the Option. The Optionee will be treated as having received
     compensation income (taxable at ordinary income tax rates) equal to the
     excess, if any, of the fair market value of the Shares on the date of
     exercise over the Exercise Price. If Optionee is an employee, Connetics
     will be required to withhold from Optionee's compensation or collect from
     Optionee and pay to the applicable taxing authorities an amount equal to a
     percentage of this compensation income at the time of exercise.

          (b) Disposition of Shares. If Shares are held for at least one year,
     any gain realized on disposition of the Shares will be treated as long-term
     capital gain for federal and California income tax purposes.

     12.  Entire Agreement. The Plan and Notice are incorporated into this
Agreement by reference. This Agreement, the Plan and the Notice constitute the
entire agreement of the parties and supersede in their entirety all prior
undertakings and agreements of Connetics and Optionee with respect to the
subject matter of this Agreement. This Agreement, the Plan and the Notice are
governed by California law except for its or any other jurisdiction's body of
law pertaining to choice of laws.

     13.  Optionee's Acknowledgements.

          (a)  Optionee represents that he or she is acquiring this option for
     his or her own account for investment purposes only and not with the view
     to or in connection with the resale or distribution of the option. Optionee
     further acknowledges that any transfer or sale of this option or any
     security under this agreement must be made in compliance with all
     applicable federal and state securities laws.

          (b)  Optionee acknowledges and agrees that the vesting of shares
     pursuant to the option hereof is earned only by continuing consultancy or
     employment at the will of Connetics (not through the act of being hired,
     being granted this option or acquiring shares under this Agreement).
     Optionee further acknowledges and agrees that nothing in this Agreement,
     nor in the Plan which is incorporated into this Agreement by reference,
     shall confer upon Optionee any right with respect to continuation of
     employment or consultancy by Connetics, nor shall it interfere in any way
     with his or her right or Connetics' right to

                                       14
<PAGE>   15
     terminate his or her employment or consultancy at any time, with or without
     cause.

          (c)  Optionee acknowledges receipt of a copy of the Plan and
     represents that Optionee is familiar with the terms and provisions of the
     Plan. Optionee has reviewed the Plan and this Option in their entirety, has
     had an opportunity to obtain the advice of counsel prior to executing this
     Option and fully understands all provisions of the Option.

CONNETICS CORPORATION
a Delaware corporation

By:
   ------------------------------------
   Thomas G. Wiggans
   President & Chief Executive Officer

OPTIONEE HEREBY ACCEPTS THIS OPTION SUBJECT TO ALL OF THE TERMS AND PROVISIONS
OF THE PLAN, AND OPTIONEE HEREBY AGREES TO ACCEPT AS BINDING, CONCLUSIVE AND
FINAL ALL DECISIONS OR INTERPRETATIONS OF THE ADMINISTRATOR UPON ANY QUESTIONS
ARISING UNDER THE PLAN OR THIS OPTION.

OPTIONEE

---------------------------------------
 <<firstname>> <<middle>> <<lastname>>

---------------------------------------
 Social Security or Tax I.D. No.

---------------------------------------
 Date

                                    ********

                                       15
<PAGE>   16

                                     Exhibit
                              CONNETICS CORPORATION
                      2000 NON-OFFICER EMPLOYEE STOCK PLAN
                          NOTICE OF STOCK OPTION GRANT

You (the "Optionee") have been granted an option (the "Option") to purchase
Common Stock of Connetics Corporation (the "Company") as follows:

     OPTIONEE'S NAME:                   <<firstname>> <<middle>> <<lastname>>

     DATE OF GRANT:                     <<grantdate>>

     GRANT NUMBER:                      <<grantnumber>>

     EXERCISE PRICE PER SHARE:           $<<optionprice>>

     TOTAL NUMBER OF SHARES GRANTED:    <<shares>>

     TOTAL PRICE OF SHARES GRANTED:      $<<totalprice>>

     TYPE OF OPTION:                     Nonstatutory Stock Option

     TERM/EXPIRATION DATE:              <<expiredate>>

     VESTING COMMENCEMENT DATE:         <<vestdate>>

     VESTING SCHEDULE:                  [ ] 1/8th of the Total Number of Shares
                                        Granted shall vest on the Vesting
                                        Commencement Date (initial grant).

                                        OR

                                        [ ] 1/4th of the Total Number of Shares
                                        Granted shall vest on the Vesting
                                        Commencement Date (ongoing grant).

                                        Thereafter, while Optionee remains an
                                        employee of or consultant to the
                                        Company, 1/48th of the Total Number of
                                        Shares Granted shall vest on each
                                        monthly anniversary of the Vesting
                                        Commencement Date, until the Total
                                        Number of Shares Granted is fully
                                        vested.

     TERMINATION PERIOD:                This Option (to the extent vested and
                                        not previously exercised) may be
                                        exercised for three months (3 months)
                                        after termination of employment or
                                        consulting relationship except as
                                        provided in Sections 4, 6, and 7 of the
                                        Stock Option Agreement (but in no event
                                        later than the Expiration Date).

By your signature and the signature of Connetics' representative on the Stock
Option Agreement, you and Connetics agree that this option is granted under and
governed by the terms and conditions of the 2000 Non-Officer Employee Stock Plan
and the Stock Option Agreement, all of which are attached and made a part of
this document.

Please contact Connetics' stock option administrator with any questions you may
have about this Option grant.

---------------------------------
Thomas G. Wiggans
President and CEO

                                     ******

                                       16

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00015-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00015-of-00352.parquet"}]]