S-8

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As filed with the Securities and Exchange Commission on May 3, 2001

Registration No. 333-     

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM S-8
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

Pharsight Corporation
(Exact name of registrant as specified in its charter)

Delaware	77-0401273
(State of Incorporation)	(I.R.S. Employer Identification No.)

800 West El Camino Real, Suite 200
Mountain View, California 94040
(650) 314-3800
(Address of principal executive offices)

2001 UK Employee Stock Purchase Plan
UK Company Share Option Plan
(Full title of the plans)

Arthur H. Reidel
President and Chief Executive Officer
Pharsight Corporation
800 West El Camino Real, Suite 200
Mountain View, California 94040
(650) 314-3800
(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:
Brett D. White, Esq.
Thomas L. MacMitchell, Esq.
COOLEY GODWARD LLP
Five Palo Alto Square
3000 El Camino Real
Palo Alto, California
(650) 843-5000

CALCULATION OF REGISTRATION FEE

Title of Securities to be Registered	Amount to be Registered	Proposed Maximum Offering Price per Share(2)	Proposed Maximum Aggregate Offering Price(2)	Amount of Registration Fee
Common Stock, par value $0.001 per share	330,000 shares	$3.095	$1,021,350	$256

(1)

130,000 shares to be registered pursuant to the 2001 UK Employee Stock Purchase Plan, and 200,000 shares to be registered pursuant to the UK Company Share Option Plan. This Registration Statement shall cover any additional shares of Common Stock which become issuable under the plans set forth herein by reason of any stock dividend, stock split, recapitalization or any other similar transaction without receipt of consideration which results in an increase in the number of shares of the Registrant's outstanding Common Stock.

(2)

Estimated solely for the purpose of calculating the amount of the registration fee pursuant to Rule 457(h). The price per share and aggregate offering price are based upon the average of the high and low prices of Registrant's Common Stock on April 30, 2001 as reported on the Nasdaq National Market.

PART II

INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE

    The following documents filed by Pharsight Corporation (the "Registrant") with the Securities and Exchange Commission are incorporated by reference into this Registration Statement:

    (a) The Registrant's latest prospectus filed pursuant to Rule 424(b) under the Securities Act of 1933, as amended (the "Act"), on August 9, 2000.

    (b) All other reports filed pursuant to Sections 13(a) or 15(d) of the Exchange Act since the end of the fiscal year covered by the prospectus referred to in (a) above.

    (c) The description of the Registrant's Common Stock which is contained in a registration statement filed on August 4, 2000 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), including any amendment or report filed for the purpose of updating such description.

    All reports and other documents subsequently filed by the Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the filing of a post-effective amendment which indicates that all securities offered have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference herein and to be a part of this registration statement from the date of the filing of such reports and documents.

ITEM 4. DESCRIPTION OF SECURITIES

    Not Applicable.

ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL

    As of April 20, 2001, GC&H Investments, an investment partnership composed of current and former partners and associates of Cooley Godward llp, owns 21,174 shares of the Registrant's Common Stock.

ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS

    Section 145 of the Delaware General Corporation Law, permits indemnification of officers, directors, and other corporate agents under certain circumstances and subject to certain limitations. The Registrant's Amended and Restated Certificate of Incorporation and Bylaws provide that the Registrant shall indemnify its directors, officers, employees and agents to the full extent permitted by the Delaware General Corporation Law, including circumstances in which indemnification is otherwise discretionary under Delaware law. In addition, the Registrant has entered into separate indemnification agreements with its directors and executive officers which require the Registrant, among other things, to indemnify them against certain liabilities which may arise by reason of their status or service (other than liabilities arising from acts or omissions not in good faith or willful misconduct).

    These indemnification provisions and the indemnification agreements entered into between the Registrant and its executive officers and directors may be sufficiently broad to permit indemnification of the Registrant's executive officers and directors for liabilities (including reimbursement of expenses incurred) arising under the Act.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED

    Not Applicable.

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ITEM 8. EXHIBITS

Exhibit Number
5.1	Opinion of Cooley Godward LLP
23.1	Consent of Ernst & Young LLP, independent auditors
23.2	Consent of Cooley Godward LLP is contained in Exhibit 5.1 to this Registration Statement
24.1	Power of Attorney is contained on the signature pages.
99.1	2001 UK Employee Stock Purchase Plan
99.2	UK Company Share Option Plan

ITEM 9. UNDERTAKINGS

    (a) The undersigned registrant hereby undertakes:

    (1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

     (i) To include any prospectus required by section 10(a)(3) of the Securities Act;

    (ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) (§ 230.424(b) of this chapter) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective registration statement;

    (iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

Provided, however, that paragraphs (a)(i) and (a)(ii) do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in periodic reports filed by the issuer pursuant to section 13 or section 15(d) of the Exchange Act that are incorporated by reference herein.

    (2) That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered herein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

    (3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

    (b) The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of the registrant's annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan's annual report pursuant to section 15(d) of the Exchange Act) that is incorporated by reference in the

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Registration Statement shall be deemed to be a new registration statement relating to the securities offered herein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

    (c) Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

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SIGNATURES

    Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Mountain View, State of California, on May 3, 2001.

PHARSIGHT CORPORATION
By:	/s/ ARTHUR H. REIDEL Arthur H. Reidel Title: President, Chief Executive Officer and Chairman of the Board

POWER OF ATTORNEY

    Know All Persons By These Presents, that each person whose signature appears below constitutes and appoints Arthur H. Reidel and Robin A. Kehoe, and each or any one of them, his or her true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for him or her and in his or her name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or any of them, or their or his or her substitutes or substitute, may lawfully do or cause to be done by virtue hereof.

    Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

Signature	Title	Date
/s/ ARTHUR H. REIDEL (Arthur H. Reidel)	President, Chief Executive Officer and Chairman of the Board	May 3, 2001
/s/ STEVEN D. BROOKS (Steven D. Brooks)	Director	May 3, 2001
/s/ PHILIPPE O. CHAMBONE (Philippe O. Chambone, M.D., Ph.D.)	Director	May 3, 2001
/s/ ROBERT B. CHESS (Robert B. Chess)	Director	May 3, 2001

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/s/ DOUGLAS E. KELLY (Douglas E. Kelly, M.D.)	Director	May 3, 2001
/s/ DEAN O. MORTON (Dean O. Morton)	Director	May 3, 2001
/s/ W. FERRELL SANDERS (W. Ferrell Sanders)	Director	May 3, 2001

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EXHIBIT INDEX

Exhibit Number
5.1	Opinion of Cooley Godward LLP
23.1	Consent of Ernst & Young LLP, independent auditors
23.2	Consent of Cooley Godward LLP is contained in Exhibit 5.1 to this Registration Statement
24.1	Power of Attorney is contained on the signature pages.
99.1	2001 UK Employee Stock Purchase Plan
99.2	UK Company Share Option Plan

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PART II INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE
ITEM 4. DESCRIPTION OF SECURITIES
ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL
ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS
ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED
ITEM 8. EXHIBITS
ITEM 9. UNDERTAKINGS

SIGNATURES
POWER OF ATTORNEY
EXHIBIT INDEX

EX-5.1

Exhibit 5.1

    [Cooley Letterhead]

May 3, 2001

Pharsight Corporation
800 West El Camino Real, Suite 200
Mountain View, California 94040

Ladies and Gentlemen:

    You have requested our opinion with respect to certain matters in connection with the filing by Pharsight Corporation (the "Company") of a Registration Statement on Form S-8 (the "Registration Statement") with the Securities and Exchange Commission covering the offering of up to 330,000 shares of the Company's Common Stock, $.001 par value, (the "Shares") pursuant to its 2001 UK Employee Stock Purchase Plan and UK Company Share Option Plan (together the "Plans").

    In connection with this opinion, we have examined the Registration Statement, your Restated and Amended Certificate of Incorporation and By-laws, as amended, and such other documents, records, certificates, memoranda and other instruments as we deem necessary as a basis for this opinion. We have assumed the genuineness and authenticity of all documents submitted to us as originals, the conformity to originals of all documents submitted to us as copies thereof, and the due execution and delivery of all documents where due execution and delivery are a prerequisite to the effectiveness thereof.

    On the basis of the foregoing, and in reliance thereon, we are of the opinion that the Shares, when sold and issued in accordance with the Plans, the Registration Statement and related Prospectus, will be validly issued, fully paid, and nonassessable (except as to shares issued pursuant to certain deferred payment arrangements, which will be fully paid and nonassessable when such deferred payments are made in full).

    We consent to the filing of this opinion as an exhibit to the Registration Statement.

Very truly yours,

COOLEY GODWARD LLP

By: /s/ BRETT D. WHITE Brett D. White

EX-23.1

Exhibit 23.1

CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS

    We consent to the incorporation by reference in the Registration Statement (Form S-8) pertaining to the 2001 UK Employee Stock Purchase Plan and the UK Company Share Option Plan of Pharsight Corporation, of our report dated May 22, 2000 (except for Note 16, as to which the date is July 10, 2000 and Note 17, as to which the date is August 8, 2000), with respect to the financial statements and schedule of Pharsight Corporation included in Amendment No. 4 to the Registration Statement (Form S-1 No. 333-34896) and related Prospectus of Pharsight Corporation filed with the Securities and Exchange Commission on August 9, 2000.

San Jose, California /s/ Ernst & Young LLP

April 27, 2001

EX-99.1

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Exhibit 99.1

PHARSIGHT CORPORATION

2001 UK EMPLOYEE STOCK PURCHASE PLAN

Adopted by the Board of Directors on April 24, 2001

1. Purpose.

    (a) The purpose of this 2001 UK Employee Stock Purchase Plan (the "Plan") is to provide a means by which UK based Eligible Employees of Pharsight Corporation, a Delaware corporation (the "Company"), and its Affiliates, as defined in subparagraph 1(b), which are designated as provided in subparagraph 2(b), may be given an opportunity to purchase stock of the Company.

    (b) The word "Affiliate" as used in the Plan means any parent corporation or subsidiary corporation of the Company.

    (c) The Company, by means of the Plan, seeks to retain the services of its Eligible Employees, to secure and retain the services of new Eligible Employees, and to provide incentives for such persons to exert maximum efforts for the success of the Company.

    (d) The words "Eligible Employee" mean any employee of the Company, or an Affiliate, who is designated as eligible to participate pursuant to the terms of an Offering adopted by the Board of Directors (the "Board") of the Company, excluding however, any such employee who is either: (i) an "Officer" (as defined in Rule 16a-1(f) promulgated under Section 16 of the Securities Exchange Act of 1934), or (ii) a member of the Board.

2. Administration.

    (a) The Plan shall be administered by the Board unless and until the Board delegates administration to a committee as provided in subparagraph 2(c). Whether or not the Board has delegated administration the Board shall have the final power to determine all questions of policy and expediency that may arise in the administration of the Plan.

    (b) The Board shall have the power, subject to, and within the limitations of, the express provisions of the Plan:

     (i) To determine when and how rights to purchase stock of the Company shall be granted and the provisions of each offering of such rights (which need not be identical).

    (ii) To designate from time to time which Affiliates of the Company shall be eligible to have their employees participate in the Plan.

    (iii) To construe and interpret the Plan and rights granted under it, and to establish, amend and revoke rules and regulations for its administration. The Board, in the exercise of this power, may correct any defect, omission or inconsistency in the Plan, in a manner and to the extent it shall deem necessary or expedient to make the Plan fully effective.

    (iv) To amend the Plan as provided in paragraph 13.

    (v) Generally, to exercise such powers and to perform such acts as the Board or the Committee deems necessary or expedient to promote the best interests of the Company and its Affiliates.

    (c) The Board may delegate administration of the Plan to a committee composed of not fewer than two (2) members of the Board (the "Committee"). If administration is delegated to a Committee, the Committee shall have, in connection with the administration of the Plan, the powers theretofore possessed by the Board, subject, however, to such resolutions, not inconsistent with the provisions of

the Plan, as may be adopted from time to time by the Board. The Board may abolish the Committee at any time and revest in the Board the administration of the Plan.

3. Shares Subject to the Plan.

    (a) Subject to the provisions of paragraph 12 relating to adjustments upon changes in stock, the shares of the Company's common stock (the "Common Stock") that may be sold pursuant to rights granted under this Plan or any other employee stock purchase plan shall not exceed in the aggregate One Hundred and Thirty Thousand (130,000) shares of Common Stock (the "Reserved Shares"). As of each January 1, beginning with January 1, 2002 and continuing through and including January 1, 2011 (the "Anniversary Date"), the number of Reserved Shares will be increased automatically by the least of (i) 1.5% of the total number of share of Common Stock outstanding on such Anniversary Date, (ii) One Hundred and Thirty Thousand (130,000) shares, or (iii) such fewer number of shares as determined by the Board prior to such Anniversary Date. If any right granted under the Plan shall for any reason terminate without having been exercised, the shares of Common Stock not purchased under such right shall again become available for the Plan.

    (b) The stock subject to the Plan may be unissued shares or reacquired shares, bought on the market or otherwise.

4. Grant of Rights; Offering.

    (a) The Board or the Committee may from time to time grant or provide for the grant of rights to purchase Common Stock under the Plan to Eligible Employees (an "Offering") on a date or dates (the "Offering Date(s)") selected by the Board or the Committee. Each Offering shall be in such form and shall contain such terms and conditions as the Board or the Committee shall deem appropriate, such that all Eligible Employees granted rights to purchase stock under the Plan shall have the same rights and privileges. The terms and conditions of an Offering shall be incorporated by reference into the Plan and treated as part of the Plan. The provisions of separate Offerings need not be identical, but each Offering shall include (through incorporation of the provisions of this Plan by reference in the document comprising the Offering or otherwise) the period during which the Offering shall be effective, which period shall not exceed twenty-seven (27) months beginning with the Offering Date, and the substance of the provisions contained in paragraphs 5 through 8, inclusive.

    (b) If an Eligible Employee has more than one right outstanding under the Plan, unless he or she otherwise indicates in agreements or notices delivered hereunder: (1) each agreement or notice delivered by that employee will be deemed to apply to all of his or her rights under the Plan, and (2) a right with a lower exercise price (or an earlier-granted right, if two rights have identical exercise prices), will be exercised to the fullest possible extent before a right with a higher exercise price (or a later-granted right, if two rights have identical exercise prices) will be exercised.

5.  Eligibility.

    (a) Rights may be granted only to Eligible Employees. Except as provided in subparagraph 5(b), an employee of the Company or any Affiliate shall not be eligible to be granted rights under the Plan unless, on the Offering Date, such employee has been in the employ of the Company or any Affiliate for such continuous period preceding such grant as the Board or the Committee may require, but in no event shall the required period of continuous employment be greater than two (2) years.

    (b) The Board or the Committee may provide that each person who, during the course of an Offering, first becomes an Eligible Employee will, on a date or dates specified in the Offering which coincides with the day on which such person becomes an Eligible Employee or occurs thereafter, receive a right under that Offering, which right shall thereafter be deemed to be a part of that

Offering. Such right shall have the same characteristics as any rights originally granted under that Offering, as described herein, except that:

     (i) the date on which such right is granted shall be the "Offering Date" of such right for all purposes, including determination of the exercise price of such right;

    (ii) the period of the Offering with respect to such right shall begin on its Offering Date and end coincident with the end of such Offering; and

    (iii) the Board or the Committee may provide that if such person first becomes an Eligible Employee within a specified period of time before the end of the Offering, he or she will not receive any right under that Offering.

    (c) No employee shall be eligible for the grant of any rights under the Plan if, immediately after any such rights are granted, such employee would own 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 Affiliate. For purposes of this subparagraph 5(c), the stock ownership of any employee shall be deemed to include any stock which such employee may purchase under all outstanding rights and options shall be treated as stock owned by such employee.

    (d) An Eligible Employee may be granted rights under the Plan only if such rights, together with any other rights granted under "employee stock purchase plans" of the Company and any Affiliates, do not permit such employee's rights to purchase stock of the Company or any Affiliate to accrue at a rate which exceeds twenty-five thousand dollars ($25,000) of fair market value of such stock (determined at the time such rights are granted) for each calendar year in which such rights are outstanding at any time.

6. Rights; Purchase Price.

    (a) Subject to the provisions of paragraphs 6(d) and 6(e), on each Offering Date under an Offering, each Eligible Employee shall be granted the right to purchase up to the number of shares of Common Stock purchasable with a percentage designated by the Board or the Committee not exceeding twenty percent (20%) of such employee's Earnings (as defined by the Board for each Offering) during the period which begins on the Offering Date (or such later date as the Board or the Committee determines for a particular Offering) and ends on the date stated in the Offering, which date shall be no later than the end of the Offering. The Board or the Committee shall establish one or more dates during an Offering (each of which is hereinafter referred to as a "Purchase Date") on which rights granted under the Plan shall be exercised and purchases of Common Stock carried out in accordance with such Offering.

    (b) 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 given 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 shall be practicable and as it shall deem to be equitable.

    (c) The purchase price of stock acquired pursuant to rights granted under the Plan shall be not less than the lesser of:

     (i) an amount equal to eighty-five percent (85%) of the fair market value of the stock on the Offering Date; or

    (ii) an amount equal to eighty-five percent (85%) of the fair market value of the stock on the Purchase Date.

    (d) On an Offering Date an Eligible Employee will not receive a right under an Offering unless such Eligible Employee on or before such Offering Date agrees to indemnify and keep indemnified the Company (and the Company as trustee for and on behalf of any Affiliate) in respect of any liability or obligation of the Company and/or any Affiliate to account for income tax under Pay As You Earn or any other taxation provisions and primary Class 1 National Insurance Contributions ("NIC") to the extent arising from the grant, cancellation, release, exchange, exercise of the rights or other disposal of the shares deriving from the rights.

    (e) On an Offering Date an Eligible Employee will not receive a right under an Offering unless such Eligible Employee on or before such Offering Date acknowledges and agrees that on becoming a participant in the Plan he shall be liable for all secondary employer's Class 1 NIC arising on any gains made, with such acknowledgment and agreement to be evidenced by executing an Inland Revenue-approved joint election in a form provided by the Company (the "Joint Election").

7. Participation; Withdrawal; Termination.

    (a) An Eligible Employee may become a participant in the Plan pursuant to an Offering by delivering a participation agreement to the Company within the time specified in the Offering, in such form as the Company provides. Each such agreement shall provide as required to effect the intent of paragraphs 6(d) and 6(e) of the Plan and shall authorize payroll deductions of up to the maximum percentage specified by the Board or the Committee of such employee's Earnings (as defined by the Board for each Offering) during the Offering. The payroll deductions made for each participant shall be credited to an account for such participant under the Plan and shall be deposited with the general funds of the Company. A participant may reduce (including to zero) or increase such payroll deductions, and an eligible employee may begin such payroll deductions, after the beginning of any Offering only as provided for in the Offering. A participant may make additional payments into his or her account only if specifically provided for in the Offering and only if the participant has not had the maximum amount withheld during the Offering.

    (b) At any time during an Offering, a participant may terminate his or her payroll deductions under the Plan and withdraw from the Offering by delivering to the Company a notice of withdrawal in such form as the Company provides. Such withdrawal may be elected at any time prior to the end of the Offering except as provided by the Board or the Committee in the Offering. Upon such withdrawal from the Offering by a participant, the Company shall distribute to such participant all of his or her accumulated payroll deductions (reduced to the extent, if any, such deductions have been used to acquire stock for the participant) under the Offering, without interest, and such participant's right to acquire Common Stock under that Offering shall be automatically terminated. A participant's withdrawal from an Offering will have no effect upon such participant's eligibility to participate in any other Offerings under the Plan but such participant will be required to deliver a new participation agreement in order to participate in subsequent Offerings under the Plan.

    (c) Rights granted pursuant to any Offering under the Plan shall terminate immediately upon cessation of a participant's employment with the Company and any designated Affiliate, for any reason, and the Company shall distribute to such terminated employee all of his or her accumulated payroll deductions (reduced to the extent, if any, such deductions have been used to acquire stock for the terminated employee), under the Offering, without interest.

    (d) Rights granted under the Plan shall not be transferable by a participant other than to his personal representatives in the event of a participant's death, or if the Participant dies intestate, the administrators of his estate or by a beneficiary designation as provided in paragraph 14, and during a participant's lifetime, shall be exercisable only by such participant.

8. Exercise.

    (a) On each Purchase Date specified in the relevant Offering, each participant's accumulated payroll deductions and any other additional payments specifically provided for in the Offering (without any increase for interest) will be applied to the purchase of whole shares of stock of the Company, up

to the maximum number of shares permitted pursuant to the terms of the Plan and the applicable Offering, at the purchase price specified in the Offering. Unless otherwise provided for in the applicable Offering, no fractional shares shall be issued upon the exercise of rights granted under the Plan. The amount, if any, of accumulated payroll deductions remaining in each participant's account after the purchase of shares which is less than the amount required to purchase one share of stock on the final Purchase Date of an Offering shall be held in each such participant's account for the purchase of shares under the next Offering under the Plan, unless such participant withdraws from such next Offering, as provided in subparagraph 7(b), or is no longer eligible to be granted rights under the Plan, as provided in paragraph 5, in which case such amount shall be distributed to the participant after such final Purchase Date, without interest. The amount, if any, of accumulated payroll deductions remaining in any participant's account after the purchase of shares which is equal to the amount required to purchase whole shares of Common Stock on the final Purchase Date of an Offering shall be distributed in full to the participant after such Purchase Date, without interest.

    (b) No rights granted under the Plan may be exercised to any extent unless the shares to be issued upon such exercise under the Plan (including rights granted thereunder) are covered by an effective registration statement pursuant to the Securities Act of 1933, as amended (the "Securities Act") and the Plan is in material compliance with all applicable state, foreign and other securities and other laws applicable to the Plan. If on a Purchase Date in any Offering hereunder the Plan is not so registered or in such compliance, no rights granted under the Plan or any Offering shall be exercised on such Purchase Date, and the Purchase Date shall be delayed until the Plan is subject to such an effective registration statement and such compliance, except that the Purchase Date shall not be delayed more than twelve (12) months and the Purchase Date shall in no event be more than twenty-seven (27) months from the Offering Date. If on the Purchase Date of any Offering hereunder, as delayed to the maximum extent permissible, the Plan is not registered and in such compliance, no rights granted under the Plan or any Offering shall be exercised then all payroll deductions accumulated during the Offering (reduced to the extent, if any, such deductions have been used to acquire stock) shall be distributed to the participants, without interest.

9. Covenants of the Company.

    (a) During the terms of the rights granted under the Plan, the Company shall at all times make reasonable efforts to keep available the number of shares of stock required to satisfy such rights, provided that this section shall not require the Company to take any action that would result in adverse tax, accounting or financial consequences to the Company.

    (b) The Company shall seek to obtain from each federal, state, foreign or other regulatory commission or agency having jurisdiction over the Plan such authority as may be required to issue and sell shares of stock upon exercise of the rights granted under the Plan. If, after reasonable efforts, the Company is unable to obtain from any such regulatory commission or agency the authority which counsel for the Company deems necessary for the lawful issuance and sale of stock under the Plan, the Company shall be relieved from any liability for failure to issue and sell stock upon exercise of such rights unless and until such authority is obtained.

10. Use of Proceeds from Stock.

    Proceeds from the sale of stock to participants pursuant to rights granted under the Plan shall constitute general funds of the Company.

11. Rights as a Stockholder.

    A participant shall not be deemed to be the holder of, or to have any of the rights of a holder with respect to, any shares subject to rights granted under the Plan unless and until the participant's shares acquired upon exercise of rights hereunder are recorded in the books of the Company (or its transfer agent).

12. Adjustments upon Changes in Stock.

    (a) If any change is made in the stock subject to the Plan, or subject to any rights granted under the Plan (through merger, consolidation, reorganization, recapitalization, stock dividend, dividend in property other than cash, stock split, liquidating dividend, combination of shares, exchange of shares, change in corporate structure or other transaction not involving the receipt of consideration by the Company), the Plan and outstanding rights will be appropriately adjusted in the class(es) and maximum number of shares subject to the Plan and the class(es) and number of shares and price per share of stock subject to outstanding rights. Such adjustments shall be made by the Board or the Committee, the determination of which shall be final, binding and conclusive. (The conversion of any convertible securities of the Company shall not be treated as a "transaction not involving the receipt of consideration by the Company.")

    (b) In the event of: (1) a dissolution or liquidation of the Company; (2) a merger or consolidation in which the Company is not the surviving corporation; or (3) a reverse merger in which the Company is the surviving corporation but the shares of Common Stock outstanding immediately preceding the merger are converted by virtue of the merger into other property, whether in the form of securities, cash or otherwise, then, as determined by the Board in its sole discretion, (i) any surviving or acquiring corporation may assume outstanding rights or substitute similar rights for those under the Plan, (ii) such rights may continue in full force and effect, or (iii) participants' accumulated payroll deductions may be used to purchase Common Stock immediately prior to the transaction described above and the participants' rights under the ongoing Offering terminated.

13. Amendment of the Plan.

    (a) The Board or the Committee at any time, and from time to time, may amend the Plan.

    (b) The Board or the Committee may amend the Plan in any respect the Board or the Committee deems necessary or advisable to provide Eligible Employees with the maximum benefits provided or to be provided under the provisions of the employee stock purchase plans and/or to bring the Plan and/or rights granted under it into compliance therewith.

    (c) Rights and obligations under any rights granted before amendment of the Plan shall not be impaired by any amendment of the Plan, except with the consent of the person to whom such rights were granted, or except as necessary to comply with any laws or governmental regulations.

14. 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 an Offering but prior to delivery to the participant 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 during an Offering.

    (b) Such designation of beneficiary may be changed by the participant at any time by written notice in the form prescribed by the Company. 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 sole 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.

15. Termination or Suspension of the Plan.

    (a) The Board or the Committee in its discretion, may suspend or terminate the Plan at any time. No rights may be granted under the Plan while the Plan is suspended or after it is terminated.

    (b) Rights and obligations under any rights granted while the Plan is in effect shall not be impaired by suspension or termination of the Plan, except as expressly provided in the Plan or with the consent of the person to whom such rights were granted, or except as necessary to comply with any laws or governmental regulation.

16. Effective Date of Plan.

    The Plan shall become effective on the date it is adopted by the Board.

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PHARSIGHT CORPORATION 2001 UK EMPLOYEE STOCK PURCHASE PLAN Adopted by the Board of Directors on April 24, 2001

EX-99.2

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Exhibit 99.2

R U L E S

OF THE

PHARSIGHT CORPORATION

UK COMPANY SHARE OPTION PLAN

     (Established by the Board of Directors on April 24, 2001
and approved by the Inland Revenue
under Schedule 9 to the Income
and Corporation Taxes Act 1988
on [    ]
under ref [    ])

1

PHARSIGHT CORPORATION

UK COMPANY SHARE OPTION PLAN

Contents

Rule
1	Definitions and Interpretation
2	Grant of Options
3	Restrictions on the Grant of Options
4	Individual limits
5	Plan limits
6	Exercise of Options
7	Lapse of Options
8	Cessation/Transfer of Employment before Exercise
9	Takeovers and Liquidations
10	Exchange of Options on a Takeover
11	Variation of Share Capital
12	Administration
13	General
14	Amendments to these Rules

2

RULES

of the

PHARSIGHT CORPORATION UK COMPANY SHARE OPTION PLAN

1.

Definitions and Interpretation

    In this Plan, the following words shall, where the context so permits, have the following meanings:

Expression	Meaning
"Stock Exchange"	means the Nasdaq National Market System, or such other exchange or market as the Board may later designate;
"Associated Company"	has the meaning given by section 416 of the Taxes Act;
"the Auditors"	Means the auditors for the time being of the Company;
"Board"	Means the Board of Directors for the time being of the Company;
"Cause"	means the occurrence of any one or more of the following: (i) the Participant's conviction of any felony or any crime involving moral turpitude or dishonesty; (ii) the Participant's participation in a fraud or act of dishonesty against the Company which results in material harm to the business of the Company; or (iii) the Participant's intentional, material violation of any contract between the Company and the Participant or any statutory duty the Participant owes to the Company that the Participant does not correct within thirty (30) days after written notice thereof has been provided to the Participant.
"the Company"	means Pharsight Corporation, a corporation registered in the State of Delaware in the United States of America;
"Committee"	means a committee of one or more members of the Board appointed by the Board in accordance with Rule 12.3.

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"Corporate Transaction"

means the occurrence of any one or more of the following: (i) a sale, lease or other disposition of all or substantially all of the securities or assets of the Company; (ii) a merger or consolidation following which the Company is not the surviving corporation; or (iii) a reverse merger following which the Company is the surviving corporation but the shares of Common Stock outstanding immediately preceding the merger are converted by virtue of the merger into other property, whether in the form of securities, cash or otherwise.

"Change in Control"

means the occurrence of any one or more of the following: (i) a Corporate Transaction after which persons who were not stockholders of the Company immediately prior to such Corporate Transaction own, directly or indirectly, immediately following such Corporate Transaction, fifty percent (50%) or more of the outstanding voting power of each of (a) the continuing or surviving entity and (b) any direct or indirect parent corporation of the continuing or surviving entity; (ii) after the IPO Date, an acquisition by any person, entity or group or any comparable successor provisions (excluding any employee benefit plan, or related trust, sponsored or maintained by the Company or an Affiliate) of the beneficial ownership of securities of the Company representing at least fifty percent (50%) of the combined voting power entitled to vote in the election of Directors; provided that such acquisition does not occur in connection with, in contemplation of or as a result of a Corporate Transaction; or (iii) after the IPO Date, during any consecutive two (2) year period the individuals who, as of the start of such period, are members of the Board (the "Inc.umbent Board"), cease for any reason to constitute at least fifty percent (50%) of the Board, provided that such change in the Inc.umbent Board does not occur in connection with, in contemplation of or as a result of a Corporate Transaction, and further provided that if the election, or nomination for election, by the Company's stockholders of any new Director was approved by a vote of at least fifty percent (50%) of the Inc.umbent Board, such new Director shall be considered as a member of the Inc.umbent Board.

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"Control"	has the meaning given by section 840 of the Taxes Act;
"Date of Grant"	means in respect of any Option the date upon which that Option is granted;
"Dealing Day"	means any weekday (excluding a Saturday or Sunday) which is not a statutory, public or bank holiday in the United Kingdom, or the United States of America;
"Eligible Employee"	Means any Full-Time Director or employee of a Participating Company who is not (a) precluded by paragraph 8 of Schedule 9 (material interest in a close company) from participating in this Plan, and (b) the Company's president, principal financial officer, principal accounting officer (or, if there is no such accounting officer, the controller), any vice-president of the Company in charge of a principal business unit, division or function (such as sales, administration or finance), any other officer who performs a policy-making function, or any other person who performs similar policy-making functions for the Company. Officers of the Company's parent(s) or subsidiaries shall be deemed officers of the Company if they perform such policy-making functions for the Company;
"Exercise Price"	means the price at which each Share subject to an Option may be acquired, being (subject to Rule 11) not less than the Market Value of a Share on the Date of Grant, provided that, if Shares are to be subscribed, the Exercise Price will be not less than the nominal value of a Share;
"Full-Time Director"	means a director of a Participating Company who is required to devote to his duties not less than 25 hours per week (excluding meal breaks);
"Grantor"	means: (a) The Company; or (b) The Participating Company by which the relevant Eligible Employee or Participant (as the context permits) is employed; or (c) With the consent of the Supervisory Board, any other person who grants an Option under this Plan; or (d) in the case of the Executives on the Board of Management the Supervisory Board;

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"Grant Period"	means any day following the approval of this Plan by the Inland Revenue under Schedule 9 and ending on [];
"Indemnified Persons"	The Company or any member of the group of companies of which the Company is a member (a "Group Company"), any associated company, any trustee of an employee benefit trust established in respect of the Company, and/or any Group Company, and/or associated company.
"Indemnity"	The indemnification to the extent it is permitted by law given by the Eligible Employee (or, as the case may be his personal representative(s)) to the Indemnified Persons on the exercise of an Option in whole or in part to indemnify and keep indemnified the Indemnified Persons in respect of any charges, tax or liability charged to suffered or Inc.urred by the Indemnified Persons either directly or indirectly from the grant, exercise or cancellation of any Option or related rights under this scheme.
"the Insider Dealing Code"	means any US or non-US legislation or agreement, arrangement, condition or contract adopted or entered into by, or which regulates, the Company and its employees or directors in relation to insider dealing;
"Market Value"	means the market value determined in accordance with Part VIII of the Taxation of Chargeable Gains Act 1992 and agreed in advance for this purpose by the Inland Revenue Shares Valuation Division;
"Option"	means a right to acquire Shares granted pursuant to the Plan;
"Option Certificate"	means a certificate issued to a Participant pursuant to Rule 2;
"Option Period"	means the period between the third and the tenth anniversary of the Date of Grant;
"Participant"	means an Eligible Employee to whom an Option has been granted under this Plan, or (where the context so requires) his legal personal representative(s);
"Participating Company"	means the Company and any other company which is for the time being nominated by the Management to be a Participating Company, being a company of which the Company has Control;

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"the Plan"	means this plan as from time to time constituted by the Rules which shall be known as the "Pharsight Corporation UK Company Share Option Plan" or such other name as the Management may from time to time decide;
"the Rules"	means these rules of the Plan as from time to time amended;
"Schedule 9"	means Schedule 9 to the Taxes Act;
"Share"	means an ordinary share in the capital of the Company which satisfies the requirements of paragraphs 10 to 14 of Schedule 9;
"Taxes Act"	means the Income and Corporation Taxes Act 1988; and
"the Pharsight Corporation Group"	means Pharsight Corporation and its branches and subsidiaries from time to time.

    References to any statutory provision are to that provision as amended or re-enacted from time to time, and, unless the context otherwise requires, words in the singular shall include the plural and vice versa and the masculine shall include the feminine and vice versa.

2.

Grant of Options

2.1

Subject to Rules 3, 4 and 5, the Grantor on the instructions of the Board may grant an Option to any Eligible Employee by issuing to him an Option Certificate in such manner as shall take effect as a legally binding agreement and which is signed by the Chief Executive Officer or another officer of the Company designated in writing by the Chief Executive Officer. The Option Certificate will form part of the Rules, and shall be in such form as the Board shall determine from time to time (subject to the approval of the Inland Revenue) and shall state:

(a)

the identity of the Grantor;

(b)

the Date of Grant of the Option;

(c)

the number and class of Shares subject to the Option; and

(d)

the Exercise Price in respect of each Share under the Option.

2.2

For the avoidance of doubt the grant of an Option in accordance with Rule 2.1 can, subject to Rule 3, be made at any time to a newly appointed Eligible Employee, even if such grant takes place at a different time to the annual grant of Options.

2.3

Each Eligible Employee to whom an Option is granted may within 30 days of the Date of Grant accept the Option by signing and returning one copy of the Option Certificate to the Grantor, or such other person as the Grantor shall direct. In the absence of such acceptance, the Option will be deemed never to have been granted under the Plan.

2.4

Participants are not required to pay for the grant of an Option.

3.

Restrictions on the Grant of Options

3.1

The Grantor shall not grant an Option to any Eligible Employee except during the Grant Period.

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3.2

No Option shall be granted to an Eligible Employee at a time when it would be in breach of the Insider Dealing Code.



3.3

Subject to the right of a deceased Participant's legal personal representative(s) to exercise an Option in accordance with these Rules, every Option shall be personal to the Participant to whom it is granted and shall not be capable of being transferred, assigned, charged, disposed of, or made subject to a security interest. If a Participant tries to transfer, assign, charge, dispose of, or make subject to a security interest, any Option or any right in respect of it, whether voluntarily or involuntarily, the Option will lapse immediately without any notice.

4.

Individual limits

4.1

Any Option granted to an Eligible Employee shall be limited and take effect so that, immediately following such grant, the aggregate Market Value of all the Shares which he may acquire on the exercise in full of all unexercised options then held by him under this Plan and any share option plan (other than a savings-related share option plan) approved by the Inland Revenue under Schedule 9 and adopted by the Company or any Associated Company of the Company, shall not exceed £30,000 (thirty thousand pounds).

4.2

For the purposes of Rule 4.1, the Market Value of Shares shall be their Market Value at the date or dates on which the relevant options were granted or such earlier time or times as may be agreed with the Inland Revenue.

5.

Plan limits

    The Board will decide the maximum number of Shares which may be placed under Option under this Plan.

6.

Exercise of Options

6.1

Subject to the rest of this Rule 6 and Rules 7 and 8, whilst a Participant remains an Eligible Employee and is not prohibited from exercise by virtue of the provisions of paragraph 8 of Schedule 9 (material interest in a close company), an unexercised Option may be exercised in whole or in multiples of 100 Shares (or the balance of Shares under the Option, if less) during the Option Period by delivery of a notice in writing to the Grantor (or such other person as the Grantor nominates). The notice shall be given in such form or manner not Inconsistent with these Rules as the Grantor may determine from time to time and be accompanied by a remittance in cleared funds for the aggregate of the Exercise Price and by the relevant Option Certificate. Such exercise shall be effective on the date that the notice, the Option Certificate and when the Company is satisfied that:

(a)

payment has been made by the Participation respect of the Exercise Price for the Shares; and

(b)

payment has been made under an Indemnity, whereby each Participant agrees to indemnify the Grantor, the Company and every Participating Company against any tax or social security claim of whatever nature or any other liability or obligation Inc.urred by the Grantor, the Company or any Participating Company which relates to the liability of a Participant in the Plan to taxation or social security contributions.

(c)

the Company is provided with a completed power of attorney in the form set out in the appendix to the Option Certificate (or such form as the Company may reasonably specify in light of the changes in law occurring after the Date of Grant of the Option) and/or a duly executed agreement and/or Joint Election which the Company may reasonably require so as to ensure that the Participant shall bear the employer's national insurance contributions (or any other tax or social security charges which may be introduced in

8

substitution or in addition thereto and which may lawfully be paid by the Participant) which may arise on grant, exercise, release or other disposal of the Option).

6.2

The allotment or transfer of Shares subject to an Option shall be conditional on the Participant complying with arrangements specified by the Grantor for the payment of any taxation (including without limitation the deduction of tax at source) and/or social security contributions. The Grantor or any other Participating Company which employs a Participant shall be entitled to make arrangements for the sale of some of the Shares to be allotted or transferred to a Participant to satisfy such Participant's tax liability and/or liability to social security contributions.



6.3

Shares allotted under this Plan shall rank pari passu in all respects with the Shares of the same class for the time being in issue save as regards any rights attaching to such Shares by reference to a record date prior to the date of allotment and in the case of a transfer of existing Shares the transferee shall not acquire any rights attaching to such Shares by reference to a record date prior to the date of such transfer.



6.4

If the exercise of Options or the allotment or transfer of Shares to a Participant could be in contravention of the Insider Dealing Code, or any securities, exchange control, tax or other laws which may be applicable to the Pharsight Corporation Group, any Eligible Employee or Participant, such exercise, allotment or transfer shall be deferred until such time when such exercise, allotment or transfer would not be in contravention of the above. The Option may be exercised and/or the Shares allotted or transferred to the Participant as soon as reasonably practicable following the first date on which the exercise, allotment or transfer would not be in such contravention.



6.5

Following the exercise of an Option in accordance with these Rules, the Grantor shall, subject to Rules 6.2 and 6.4, ensure that the relevant Shares are allotted or transferred to the Participant within 30 days of the exercise of the Option.



6.6

If and so long as the Shares are listed on the Stock Exchange, the Company shall apply for any Shares allotted under this Plan to be admitted to the list of such Stock Exchange.

7.

Lapse of Options

    An Option will lapse without notice on the earliest of the following:

(a)

3 months from the date of cessation of employment of a Participant other than in circumstances where the exercise of Options is permitted under Rule 8 or Rule 9;



(b)

any of the dates specified in Rule 8 or Rule 9 for such lapse;



(c)

the end of the Option Period;



(d)

the date on which a Participant is declared bankrupt or makes an arrangement or compromise with his creditors; and



(e)

the date on which a resolution is passed or an order is made by the Court for the compulsory winding up of the Company.

8.

Cessation/Transfer of Employment Before Exercise

8.1

If a Participant ceases to be an Eligible Employee (whether before or after his Options become exercisable) by reason of the following:

(a)

death;

(b)

disability, injury or ill-health (evidenced to the satisfaction of the Board);

9

(c)

redundancy (within the meaning of the Employment Rights Act 1996);



(d)

retirement at contractual retirement age or early retirement;



(e)

the Participant entering into a contract of employment with an Associated Company; or



(f)

any other reason which the Board considers reasonably justifies the continuance of the Option

then his unexercised Options shall not lapse by reason of such cessation. Subject to Rules 6.1, 6.2 and 6.4, all unexercised Options may then be exercised and will lapse as follows:

(i)

in the case of death or disability injury or ill-health at any time before the earliest of the end of the Option Period and 12 months following the date of the Participant's death; and



(ii)

in all other cases at any time before the earliest of the end of the Option Period and 3 months after the end of the Participant's employment whereupon, if unexercised, all Options will lapse.




8.2

If a Participant ceases to be an Eligible Employee for a reason other than those set out in Rule 8.1, the unexercised Options will lapse without further notice 3 months from the date of cessation and without any compensation.



8.3

If, while continuing to hold an office or employment with a Participating Company, a Participant is to be transferred to work in another country or jurisdiction and the Board is satisfied that as a result of such transfer either:



(a)

he will suffer a tax disadvantage on exercising his Option; or



(b)

he will become subject to restrictions on his ability to exercise his Option or to deal in the Shares obtained upon exercise of his Option, the Participant may, subject to Rules 6.1, 6.4 and 7, exercise all or any of his Options in whole or in part in the period commencing three months before and ending three months after the date of such transfer (but so that any exercise before the date of transfer shall be conditional upon such transfer taking place). Upon the expiry of such period, all Options to the extent unexercised shall cease to be exercisable under this Rule 8.3 but shall continue to be exercisable at such other time or times as may be permitted by these Rules.




8.4

Following exercise under Rule 8.1, the allotment or transfer of the Shares will take place as described in Rule 6.

9.

Takeovers and Liquidations

9.1

(a)

In the event of a Corporate Transaction, any surviving corporation or acquiring corporation may assume any unexercised Options or may substitute similar options (including an award to acquire the same consideration paid to the stockholders pursuant to Corporate Transaction). In the event any surviving corporation or acquiring corporation refuses to assume such unexercised Options or to substitute similar unexercised options for those Options, then with respect to Options held by Participants whose employment has not terminated as of the effective date of the Corporate Transaction, the vesting of such Options (and, if applicable, the time during which such Options may be exercised) shall be accelerated in full, and such Options shall terminate if not exercised (if applicable) at or prior to such effective date. With respect to any other unexercised Options, such Options shall terminate on the effective date of the Corporate

10

Transaction to the extent not exercised (if applicable) prior the effective date of the Corporation Transaction.

(b)

If a Change in Control occurs and within thirteen (13) months after the effective date of such Change in Control the employment of a Participant terminates due to an involuntary termination (not including death or disability) without Cause, then the vesting and exercisability of all Options held by such Participant shall accelerate in full.




9.2

Dissolution or Liquidation. In the event of a dissolution or liquidation of the Company, then all unexercised Options shall terminate immediately prior to such event.

10.

Exchange of Options on a Takeover

10.1

Notwithstanding the provisions of Rule 9, if any company ("the Acquiring Company") obtains Control of the Company or becomes bound or entitled to acquire shares in the Company within the circumstances specified in Rules 9.1, any Participant may at any time within the appropriate period (as specified in Rule 9), by agreement with the Acquiring Company, release his Option ("the Old Option") in consideration of the grant to him of a new option ("the New Option") which is equivalent to the Old Option (by virtue of satisfying the requirements of paragraph 15(3) of Schedule 9) but relates to shares in a different company (whether the Acquiring Company itself or some other company which, on the assumption that the Acquiring Company were the grantor, would be a company falling within paragraph (b) or (c) of paragraph 10 of Schedule 9). Where any New Options are granted pursuant to this Rule 10.1 they shall be regarded for the purposes of the subsequent application of the provisions of this Plan as having been granted at the time when the corresponding Old Options were granted and, with effect from the date on which the New Options are granted, these Rules shall, in relation to the New Options, be construed as if references to the Company and to the Shares were references to the Acquiring Company and to shares in the Acquiring Company or, as the case may be, to the other company to whose shares the New Options relate and to the shares in that other company, but references to Participating Companies shall continue to be construed as if references to the Company were references to Pharsight Group.

10.2

As soon as practicable after having granted the New Option in accordance with the provisions of Rule 10.1, the Acquiring Company shall issue an option certificate in respect of such Option or shall procure that such an option certificate is issued. The option certificate shall state:

(a)

the date on which the Old Option (which has been released in consideration of the grant of the New Option) was granted;

(b)

the number and class of Shares subject to the New Option;

(c)

the Exercise Price payable for each Share under the New Option; and

(d)

the last date on which a notice exercising the New Option can be given,

and subject as aforesaid shall be issued in such form and manner as the Board may from time to time prescribe.

11.

Variation of Share Capital

11.1

In the event of any capitalisation, consolidation, sub-division or reduction of the share capital of the Company and in respect of any discount element in any rights issue or any other variation in the share capital of the Company:

(a)

the number of Shares comprised in an Option;

11

(b)

their Exercise Price; and



(c)

where an Option has been exercised but no Shares have been allotted or transferred in satisfaction of such exercise, the number of Shares to be so allotted or transferred and their Exercise Price;

may, subject to the prior approval of the Inland Revenue, be varied in such manner as the Grantor with the approval of the Board shall determine and (save in the event of a capitalisation) the Auditors shall confirm in writing to be in their opinion fair and reasonable, provided that no variation shall be made which would result in the Exercise Price for an allotted Share being less than its nominal value.

11.2

The Grantor may take such steps as it considers necessary to notify Participants of any adjustment made under Rule 11.1 and to call in, cancel, endorse, issue or re-issue any Option Certificate consequent upon such adjustment.

12.

Administration

12.1

The Board shall have power from time to time to make and vary such regulations (not being Inconsistent with these Rules) for the implementation and administration of the Plan as it thinks fit.

12.2

The decision of the Board shall be final and binding in all matters relating to this Plan (other than in the case of matters to be determined or confirmed by the Auditors in accordance with this Plan).

12.3

The Board may delegate administration of the Plan to a Committee or Committees of one (1) or more members of the Board, and the term "Committee" shall apply to any person or persons to whom such authority has been delegated. If administration is delegated to a Committee, the Committee shall have, in connection with the administration of the Plan, the powers theretofore possessed by the Board, including the power to delegate to a subcommittee any of the administrative powers the Committee is authorised to exercise (and references in this Plan to the Board shall thereafter be to the Committee or subcommittee), subject, however, to such resolutions, not Inconsistent with the provisions of the Plan, as may be adopted from time to time by the Board. The Board may abolish the Committee at any time and revest in the Board the administration of the Plan.

12.4

The costs of establishing and administering this Plan shall be borne by the Grantor. The costs of exercise shall be borne by the relevant Participant.

12.5

The Grantor shall not be obliged to provide Eligible Employees or Participants with copies of any notices, circulars or other documents sent to shareholders of the Company.

12.6

Any notification or other notice which the Grantor is required to give or may desire to give to any Eligible Employee or Participant pursuant to the Plan must be personally delivered or sent by ordinary post in a prepaid envelope addressed to his address last known to the Company.

12.7

Any notice sent by post (by airmail if overseas) shall be deemed to be properly served four working days after an envelope containing such notice and properly addressed has been posted by first class prepaid post (or if sent airmail from or to overseas on the fifth day following the day of posting). Share certificates and other communications sent by post will be sent at the risk of the Eligible Employee or Participant. The Grantor shall only accept liability in respect of any notification, document, or other communication so given or sent to it by a Participant or Eligible Employee, where the sender can prove postage/transmission.

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12.8

Any notice given by an Eligible Employee or a Participant to the Grantor pursuant to the Plan must be given in writing and signed by the Eligible Employee or Participant as the case may be and shall be acted upon by the Company as soon as practicable after receipt. Any such notice shall be properly given if sent by prepaid registered post (by airmail if overseas) or delivered to the Grantor at its registered offices. The Grantor may, in its absolute discretion, act on notices, requests or instructions given or purporting to be given by facsimile and shall not be responsible for any loss whatsoever occasioned by so acting. All faxes must be confirmed by prepaid post.

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13. General

13.1

This Plan shall commence upon the date of its approval by the Inland Revenue and shall terminate as set forth by a resolution of the Board. Upon termination (howsoever occurring) no further Options may be granted but such termination shall be without prejudice to any accrued rights in existence at the date thereof.

13.2

The Company will ensure that sufficient Shares will be available to satisfy the exercise to the full extent possible of all unexercised Options.

13.3

Notwithstanding any other provisions of this Plan:

(a)

this Plan shall not form part of any contract of employment between any Participating Company and any employee of any such company. The rights and obligations of any individual under the terms of his office or employment with any Participating Company shall not be affected by his participation in this Plan or any right which he may have to participate in it, and this Plan shall afford such an individual no additional rights to compensation or damages in consequence of the termination of such office or employment for any reason whatsoever;

(b)

no Participant shall be entitled to any compensation or damages for any loss or potential loss which he may suffer by reason of being unable to exercise an Option in consequence of the loss or termination of his office or employment with any Participating Company for any reason whatsoever;

(c)

this Plan shall not confer on any person any legal or equitable rights (other than those constituting the Options themselves) against any Participating Company directly or indirectly, or give rise to any cause of action at law or in equity against any Participating Company.

13.4

All Participants and Eligible Employees agree as a condition of their participation in the Plan that any personal data in relation to them may be held by any company in the Pharsight Corporation Group and/or passed to any third party where necessary for the administration of the Plan.

13.5

This Plan and all Options granted under it shall be governed by and construed in accordance with English law.

14. Amendments to these Rules

14.1

The Board may, prior to approval of this Plan by the Inland Revenue under Schedule 9, alter the Rules of this Plan as may be necessary in order to obtain such approval.

14.2

After the date on which the Plan is approved by the Inland Revenue under Schedule 9, the Board may amend the provisions of this Plan and the terms of the Options as it considers necessary or desirable in order to:

(a)

benefit the administration of the Plan; or

(b)

comply with or take account of the provisions of any proposed or existing legislation

14.3

For so long as this Plan is to continue to be approved by the Inland Revenue under Schedule 9, no amendment pursuant to Rule 14.1 and Rule 14.2 shall have effect until approved by the Inland Revenue.

14.4

Written notice of any amendment to this Plan shall be given to all Participants.

13

OPTION CERTIFICATE
[STANDARD OPTION GRANT FOR PARTICIPANTS IN UK]

THIS CERTIFICATE IS IMPORTANT AND SHOULD BE
KEPT IN A SAFE PLACE

PHARSIGHT CORPORATION UK COMPANY SHARE OPTION PLAN
("the Plan")

Option Certificate

Note: The words in this option certificate shall bear the same meaning as the words defined in the rules of the Plan ("the Plan Rules").

This is to certify that [TITLE] [FIRST NAME] [SURNAME] is the holder of an Option to acquire [NUMBER OF OPTIONS] ordinary Shares in Pharsight Corporation at a price of $[VALUE] per Share.

This Option was granted on [  ] under the Rules of the Pharsight Corporation UK Company Share Option Plan to which English Law applies.

The Option is exercisable in accordance with the Plan rules ("Rules") as they are amended from time to time and should not in any event be exercised later than the tenth anniversary from the Date of Grant shown above. In particular, the following should be noted:

To ensure Income tax is not Inc.urred on the exercise of the Option, in addition to complying with the Rules of the Plan, the exercise must take place:

•

not less than three years after the Option was granted; and



•

not within three years of the latest previous exercise by the Option Holder of an Option (obtained under this or any other plan (not being a savings-related share option plan) approved by the Inland Revenue) which enjoyed relief from Income tax.

The Option is not transferable and will lapse upon the occasion of any assignment, charge, disposal or other dealing with the rights conveyed by it.

The terms of this Option Certificate are governed by English law.

EXECUTED as a Deed by	)
Pharsight Corporation
acting by:	)

Chief Executive Officer
Chief Financial Officer

14

I HEREBY AGREE to accept the grant of the Option and agree and undertake:

1.

to be bound by the terms and conditions set out in the Scheme Rules; and

2.

to indemnify the Company in respect of any Income tax to be accounted for under PAYE and any primary (employee) class 1 National Insurance Contributions ("NICs") and secondary (employer) class 1 NICs arising on exercise, release or other disposal of the Option; and

3.

to return to the company the completed, signed and witnessed and power of attorney that is appended to this Option Certificate; and

4.

if the Company so requires, to pay to the Company (as trustee for the Indemnified Persons if appropriate) at the date of exercise release or other disposal a cash amount equal to the liability of any Indemnified Person to account to any revenue or other authority for any sum in respect of any tax to be accounted for under PAYE and any primary (employee) class 1 NICs and any secondary class 1 (employer) NICs (or any other tax or social security charges which may be introduced in substitution or addition thereto and which may lawfully be paid by the holder of the Option) for which any of the Indemnified Persons is liable as a result of the exercise of the Option or the resulting issue or transfer of Shares; and

5.

if the Company so requires, to enter into a duly executed agreement and/or joint election so as to ensure that the I the Participant shall bear the employer's NICs (or any other tax or social security charges which may be introduced in substitution or in addition thereto and which may lawfully be paid by the Participant) which may arise on exercise, release or other disposal of the Option.

This Deed has been executed and delivered as a deed on the date set out above.

SIGNED by	)
in the presence of:	)

Signature:
(Print in capitals	)
Name of Witness:
Address:
Occupation:

15

APPENDIX TO OPTION CERTIFICATE
POWER OF ATTORNEY [UK]

By this Power of Attorney made on [            ], I [            ] of [            ] HEREBY APPOINT Pharsight Corporation (the "Company") to act as my attorney with authority in my name and on my behalf to sign or execute any and all agreements, instruments, deeds or other papers and to do all things in my name as may be necessary to facilitate the sale on whatever terms the Company may determine of sufficient number of the ordinary shares in the Company issued or transferred to me on the exercise of the option granted to me on [            ] to fund the payment of any Income tax to be accounted for under PAYE and any primary (employee) class 1 and secondary (employer) Class 1 National Insurance Contributions (NICs) (or any tax or social security charges which may be introduced in substitution or addition thereto and which may lawfully be paid by the Participant) to be accounted for by the Company (or any company in the same group of companies as the Company, any company associated with the Company or the trustees of any employee benefit trust established in respect of the Company and/or any other companies in the same group of companies as the Company) together with any Inc.idental costs Inc.urred in connection with the sale of such Shares.

I declare that this Power of Attorney, having been given to me to secure my obligations in connection with the terms of the conditions applicable to the exercise of my Option under the Pharsight Corporation UK Company Share Option Plan shall be irrevocable in accordance with Section 4 of the Powers of Attorney Act 1971.

IN WITNESS whereof this Power of Attorney has been duly EXECUTED as a DEED and DELIVERED by

)
)
)

Witness Signature:

Name of Witness:

Address:

Occupation:

16

NOTICE OF EXERCISE OF SHARE OPTION
PHARSIGHT CORPORATION

To: The Company Secretary, Pharsight Corporation

I hereby exercise the Option referred to in the Option Certificate dated ([            ]) in respect of all/        * of the shares over which the Option may be exercised, and request the allotment or transfer to me of those shares in accordance with the Agreement.

I enclose a cheque made payable to Pharsight Corporation [            ] in the sum of £      being the aggregate Exercise Price of such shares.

Name (block letters)		Signature
Address
	Date

NOTES:

1.

This form must be accompanied by payment of the Exercise Price for the shares in respect of which the Option is exercised and either payment of such sum as [      ] has required to be paid and/or a duly executed power of attorney in each case in accordance with the conditions of exercise set out in the Appendix to the Option Certificate and/or a duly executed agreement and/or joint election which the Company may reasonably require so as to ensure that the Optionholder shall bear the employer's National Insurance Contributions (or any other tax or social security charges which may be introduced in substitution or in addition thereto and which may lawfully be paid by the Optionholder) which may arise on grant, exercise, release or other disposal of the Option.

2.

Where the Option is exercised by personal representatives, an office copy of the Probate or Letters of Administration should accompany the form.

3.

IMPORTANT: The Plan has been approved by the Inland Revenue under Schedule 9 to the Income and Corporation Taxes Act 1988. However, Pharsight Corporation does not undertake to advise you on the tax consequences of exercising your Option. If you are unsure of the tax liabilities which may arise, you should take appropriate professional advice before exercising your Option.

* Delete/insert number as appropriate

17

DECLARATION 1
To be typed on the letterhead of Pharsight Corporation

I declare that the shares to be issued in the Pharsight Corporation Company Approved Share Plan Scheme satisfy the conditions in paragraphs 10 to 14 (inclusive), Schedule 9, ICTA 1988. Namely that the shares are:

1.

part of the ordinary share capital of the parent company;

2.

shares in a company not controlled by another company;

3.

fully paid up and irredeemable;

4.

not be subject to any restrictions not attaching to all shares of the same class (although the articles may require directors and employees to sell their shares for money on specified terms on leaving employment (or on acquisition, if this takes place after employment has ceased) so long as other shareholders may be required under the articles to sell their shares on the same terms); and

5.

part of the only class of ordinary shares¹.

Signed

Company Secretary

Date

¹

Ordinary share capital means all the issues share capital (by whatever name called) of the company other than capital the holders of which have a right to a dividend at a fixed rate but have other right to share in the profits of the company.

18

DECLARATION 2
To be typed on the letterhead of Pharsight Corporation

We the Directors of Pharsight Corporation declare that we will not use our power to vote for the transfer of shares in any way to discriminate against the transfer of shares acquired under the Pharsight Corporation Company Approved Share Option Plan ("the Plan"), and that employees participating in the Scheme will be informed of this declaration.

Signed

Company Secretary

Date

19

QuickLinks

R U L E S OF THE PHARSIGHT CORPORATION UK COMPANY SHARE OPTION PLAN
PHARSIGHT CORPORATION UK COMPANY SHARE OPTION PLAN

Contents

RULES of the PHARSIGHT CORPORATION UK COMPANY SHARE OPTION PLAN

13. General
14. Amendments to these Rules

OPTION CERTIFICATE [STANDARD OPTION GRANT FOR PARTICIPANTS IN UK] THIS CERTIFICATE IS IMPORTANT AND SHOULD BE KEPT IN A SAFE PLACE PHARSIGHT CORPORATION UK COMPANY SHARE OPTION PLAN ("the Plan") Option Certificate
APPENDIX TO OPTION CERTIFICATE POWER OF ATTORNEY [UK]
NOTICE OF EXERCISE OF SHARE OPTION PHARSIGHT CORPORATION
DECLARATION 1 To be typed on the letterhead of Pharsight Corporation
DECLARATION 2 To be typed on the letterhead of Pharsight Corporation