Exhibit
10.46       March 13, 2003 VIA HAND DELIVERY  Michael Schwartz Pharsight Corporation Dear Michael: As we have discussed, Pharsight Corporation (Pharsight or the
Company) is offering you continued employment through April 30, 2003 and
severance benefits under the terms and conditions set forth below (the
Agreement). 1.             Continued Employment.Provided that you continue to satisfactorily perform
your job duties, and comply with Company policies and procedures, subject to
Paragraph 4 below, the Company may continue to employ you through April 30,
2003 (the Separation Date) and you will continue to be paid your regular base
salary as of the date of this Agreement during the period of such continued
employment. 2.             Accrued Salary, and Paid Time Off.On the Separation Date, the Company will pay you all accrued and unpaid
salary, and all accrued and unused vacation, earned through the Separation
Date, less required payroll deductions and withholdings.  You are entitled to these payments
regardless of whether you sign this Agreement. 3.             Severance Benefits.If you fully comply with all conditions of this Agreement (including
continuing to work through the Separation Date), and sign and return the
Supplemental Release (attached hereto as Exhibit A) on or after the Separation
Date, the Company will provide you with a severance payment equal to fifty
thousand dollars ($50,000), subject to required payroll deductions and required
withholdings, (the Severance Payment). 
The Severance Payment will be provided within ten (10) business days
after the Effective Date of the Supplemental Release (as defined therein).   In addition, provided you timely elect
COBRA continuation coverage as provided in Section 5 below, the Company will
reimburse you for your COBRA premiums from the Separation Date through July 31,
2003. 4.             Termination of
Employment Prior To Separation Date.The Company can terminate your employment
prior to the Separation Date with or without Cause, upon notice to you.  In addition, you can terminate your
employment prior to the Separation Date for any reason upon notice to the
Company.  If, prior to the Separation
Date, the Company terminates your employment without Cause, and provided that you must first sign and
return the Supplemental Release to the Company, you will be entitled to
receive, as your sole severance 1 
   compensation, the
Severance Payment.  You will not be
entitled to receive the payment referenced in the immediately preceding sentence
if your employment is terminated for Cause or you resign for any reason prior
to the Separation Date.  For the
purposes of this Agreement, Cause for termination of your employment by the
Company shall mean:  (a) your
conviction (including a guilty or no contest plea) of any felony or any other
crime involving dishonesty; (b) your participation in any fraud against the
Company; (c) your breach of any obligation under this Agreement; (d) your
damage to any Company property; or (e) conduct by you which in the good faith
and reasonable determination of the Companys Board of Directors demonstrates
gross unfitness to serve. 5.             Health Insurance.To the extent provided by the federal COBRA law or, if applicable, state
insurance laws, and by the Companys current group health insurance policies,
you will be eligible to continue your group health insurance benefits at your
own expense after the Separation Date. 
Later, you may be able to convert to an individual policy through the
provider of the Companys health insurance, if you wish.  You will be provided a separate notice
describing your rights and obligations under COBRA on or after the Separation
Date. 6.             Other Compensation or Benefits.You acknowledge that, except as expressly provided in this Agreement you
will not receive any additional compensation, severance, stock option vesting,
or benefits before or after the Separation Date.  By way of example, but not limitation, you acknowledge and agree
that you are not eligible for any bonus or other incentive compensation. 7.             Expense Reimbursements.Within ten (10) business days following the Separation Date (or any
earlier termination date), you must submit your final documented expense
reimbursement statement reflecting all business expenses you incurred through
the Separation Date, if any, for which you seek reimbursement.  The Company will reimburse you for these
expenses pursuant to its regular business practices. 8.             Return of Company Property.You agree to return to the Company, no later than the Separation Date or
at the Companys earlier request, all Company documents (and all copies
thereof) and other Company property that you have in your possession or
control, including, but not limited to, Company files, notes, drawings,
records, business plans and forecasts, financial information, specifications,
computer-recorded information, tangible property (including, but not limited
to, computers), credit cards, entry cards, identification badges and keys; and,
any materials of any kind that contain or embody any proprietary or
confidential information of the Company (and all reproductions thereof).  The timely return of such property is a
condition precedent to the Company providing you with the severance benefits
contained herein. 9.             Proprietary Information Obligations.You hereby acknowledge and reaffirm your continuing obligations under
your Proprietary Information and
Inventions Agreement, which apply both during and after your employment. A copy of your Proprietary Information and Inventions
Agreement is attached hereto as Exhibit B. 10.          Confidentiality.The provisions of this Agreement will be held in strictest confidence by
you and the Company and will not be publicized or disclosed in any manner
whatsoever; provided,
however, that:  (a) you may
disclose this Agreement in confidence to your immediate family; (b) the parties
may disclose this Agreement in confidence to their respective attorneys,
accountants, auditors, tax preparers, and financial advisors; (c) the Company
may disclose 2 
   this Agreement to
investors or potential investors and to fulfill standard or legally required
corporate reporting or disclosure requirements; and (d) the parties may
disclose this Agreement insofar as such disclosure may be necessary to enforce
its terms or as otherwise required by law. 
In particular, and without limitation, you agree not to disclose the
terms of this Agreement to any current or former employee, consultant or independent
contractor of the Company. 11.          Nondisparagement.You agree that you will not at any time disparage the
Company or its directors, officers, shareholders, agents, or employees in any
manner likely to be harmful to the personal or business reputation of it or
them, and the Company (through its officers and directors) agrees that it will
not disparage you in any manner likely to be harmful to your personal or
business reputation, provided that both you and the Company shall respond
accurately and fully to any question, inquiry, or request for information when
required by legal process. 12.          Cooperation.You agree to cooperate with the Company in
responding to the Companys requests in connection with any existing or future
litigation, arbitrations, mediations or investigations brought by or against
the Company or any of its affiliates, agents, officers, directors or employees,
whether administrative, civil or criminal in nature, in which the Company
reasonably deems your cooperation necessary or desirable.  In such matters, you agree to provide the
Company with reasonable advice, assistance and information, including offering
and explaining evidence, providing sworn statements, and participating in
discovery and trial preparation and testimony. 
You also agree to promptly send the Company copies of all correspondence
(for example, but not limited to, subpoenas) received by you in connection with
any such legal proceedings, unless you are expressly prohibited by law from so
doing.  You will act in good faith to
furnish the information and cooperation required by this paragraph and the
Company will act in good faith so that the requirement to furnish such
information and cooperation does not create an undue hardship for you.The Company will reimburse you for reasonable out-of-pocket expenses
incurred by you as a result of your cooperation, with the exception of lost
compensation, within ten (10) days of the presentation of appropriate
documentation thereof, in accordance with the Companys standard reimbursement
policies and procedures. 13.          Nonsolicitation of
Company Employees.You hereby agree that during your continued employment
and for six (6) months after the termination of your employment for any reason,
you will not, either directly or indirectly, solicit, attempt to solicit,
induce or otherwise cause any employee of the Company to terminate his or her
employment with the Company. 14.          Release of Claims.In consideration for, and as a condition of, your
continued employment and other consideration provided to you by the Company
under this Agreement, to which you are not otherwise entitled, you hereby
generally and completely release the Company and Execustaff, Inc., its
directors, officers, employees, shareholders, partners, agents, attorneys,
predecessors, successors, parent and subsidiary entities, insurers, affiliates,
and assigns from any and all claims, liabilities and obligations, both known
and unknown, that arise out of or are in any way related to events, acts,
conduct, or omissions occurring at any time prior to and including the date you
sign this Agreement.  This general
release includes, but is not limited to: (1) all claims arising out of or in
any way related to your employment with the Company or the termination of that
employment; (2) all claims related to your compensation or benefits from the
Company, including salary, bonuses, commissions, vacation pay, expense
reimbursements, severance pay, fringe benefits, stock, stock options, or any
other ownership interests in the Company; (3) all claims for breach of
contract, 3 
   wrongful termination, and
breach of the implied covenant of good faith and fair dealing; (4) all
tort claims, including claims for fraud, defamation, emotional distress, and
discharge in violation of public policy; and (5) all federal, state, and local
statutory claims, including claims for discrimination, harassment, retaliation,
attorneys fees, or other claims arising under the federal Civil Rights Act of
1964 (as amended), the federal Americans with Disabilities Act of 1990, the
federal Age Discrimination in Employment Act (as amended) (ADEA), and the
California Fair Employment and Housing Act (as amended). 15.          ADEA Waiver.You acknowledge that you are knowingly
and voluntarily waiving and releasing any rights you may have under the ADEA,
and that the consideration given for the waiver and release in the preceding
paragraph is in addition to anything of value to which you were already
entitled.  You further acknowledge that
you have been advised by this writing that:  (a) your waiver and release do not
apply to any rights or claims that may arise after the date you sign this
Agreement; (b) you should consult with an attorney
prior to signing this Agreement (although you may not choose to do so); (c) you have twenty-one (21) days to consider this
Agreement (although you may choose voluntarily to sign this Agreement earlier); (d) you have seven (7) days following the date you sign
this Agreement to revoke the Agreement; and (e) this
Agreement will not be effective until the date upon which the revocation period
has expired, which will be the eighth calendar day after the date you sign this
Agreement (the Effective Date). 16.          Release of Unknown Claims.You acknowledge that you have read and understand
Section 1542 of the California Civil Code: 
A
general release does not extend to claims which the creditor does not know or
suspect to exist in his favor at the time of executing the release, which if
known by him must have materially affected his settlement with the debtor. You hereby expressly waive and relinquish all
rights and benefits under that section and any law of or legal principle of
similar effect in any jurisdiction with respect to your release of claims
herein, including but not limited to the release of unknown and unsuspected
claims. 17.          Arbitration.To ensure rapid and economical resolution of any
disputes which may arise under this Agreement, you and the Company agree that
any and all disputes or controversies of any nature whatsoever arising from or
regarding the interpretation, performance, enforcement or breach of this
Agreement shall be resolved, to the fullest extent allowed by law, by
confidential, final and binding arbitration conducted before a single
arbitrator with Judicial Arbitration and Mediation Services, Inc. (JAMS) in
San Francisco, California, under the then-existing JAMS employment rules.  The parties  acknowledge that by agreeing to this
arbitration procedure, they each waive the right to resolve any such dispute
through a trial by jury, judge or administrative proceeding.  The arbitrator shall:  (a) have the authority to compel
adequate discovery for the resolution of the dispute and to award such relief
as would otherwise be permitted by law; and (b) issue a written arbitration decision
including the arbitrators essential findings and conclusions and a statement
of the award.  The Company shall pay all
JAMS arbitration fees in excess of those which would be required if the
dispute were decided in a court of law. 
Nothing in this Agreement is intended to prevent either you or the
Company from obtaining injunctive relief in court to prevent irreparable harm
pending the conclusion of any such arbitration.  Notwithstanding the foregoing, you and the Company each have the
right to resolve any issue or dispute involving Company trade secrets or
invention rights by court action instead of arbitration. 4 
   18.          Miscellaneous.This Agreement, including Exhibits A and B, constitutes the complete,
final and exclusive embodiment of the entire agreement between you and the
Company with regard to its subject matters. 
It is entered into without reliance on any promise or representation,
written or oral, other than those expressly contained herein, and it supersedes
any other such promises, warranties or representations. (This Agreement does
not however, supersede the Arbitration Agreement between you, the Company and
Execustaff, Inc. dated December 3, 2002.) 
This Agreement may not be modified or amended except in a writing signed
by both you and a duly authorized officer of the Company.  This Agreement will bind the heirs, personal
representatives, successors and assigns of both you and the Company, and inure
to the benefit of both you and the Company, their heirs, successors and
assigns.  If any provision of this
Agreement is determined to be invalid or unenforceable, in whole or in part,
this determination will not affect any other provision of this Agreement and
the provision in question will be modified by the court so as to be rendered
enforceable.  This Agreement will be
deemed to have been entered into and will be construed and enforced in
accordance with the laws of the State of California as applied to contracts
made and to be performed entirely within California. We hope the foregoing terms are acceptable to you.  If you agree to the terms set forth in this
Agreement, please sign below and return the original to me.  You have up to twenty-one (21) calendar days
to decide whether you want to accept the Companys offer contained herein.  If you have any questions regarding these
matters, feel free to contact me. We wish you good luck in your future endeavors. Sincerely, Pharsight Corporation By:
  /s/  Shawn OConnorShawn
  OConnorPresident
  and Chief Executive Officer   Exhibit A  Supplemental Release Exhibit B  Proprietary
Information and Inventions Agreement  Agreed:
  Accepted
  and Agreed:/s/  Michael Schwartz
  
  /s/ Susan
  JochheimMichael Schwartz
  Susan Jochheim,
  Execustaff, Inc.Date:
  March 21, 2003
  
  Date:
  March 24, 2003  5 
   Exhibit A SUPPLEMENTAL RELEASE (to be signed on or after the Separation Date) In
consideration for the severance payment and other consideration provided to me
by Pharsight Corporation (the Company) and Execustaff, Inc., and as required
by the Agreement between the Company and me dated March 13, 2003, I hereby give
the following Supplemental Release. I hereby generally and completely release the Company
and Execustaff, Inc. and their directors, officers, employees, shareholders,
partners, agents, attorneys, predecessors, successors, parent and subsidiary
entities, insurers, affiliates, and assigns from any and all claims,
liabilities and obligations, both known and unknown, that arise out of or are
in any way related to events, acts, conduct, or omissions occurring at any time
prior to and including the date I sign this Supplemental Release.  This general release includes, but is not
limited to: (1) all claims arising out of or in any way related to my
employment with the Company or the termination of that employment; (2) all
claims related to my compensation or benefits from the Company, including
salary, bonuses, commissions, vacation pay, expense reimbursements, severance
pay, fringe benefits, stock, stock options, or any other ownership interests in
the Company; (3) all claims for breach of contract, wrongful termination,
and breach of the implied covenant of good faith and fair dealing; (4) all
tort claims, including claims for fraud, defamation, emotional distress, and
discharge in violation of public policy; and (5) all federal, state, and local
statutory claims, including claims for discrimination, harassment, retaliation,
attorneys fees, or other claims arising under the federal Civil Rights Act of
1964 (as amended), the federal Americans with Disabilities Act of 1990, the
federal Age Discrimination in Employment Act (as amended) (ADEA), and the
California Fair Employment and Housing Act (as amended). Iacknowledge that I am knowingly and
voluntarily waiving and releasing any rights I may have under the ADEA, and
that the consideration given for the waiver and release in the preceding
paragraph is in addition to anything of value to which I am already entitled.  I further acknowledge that I have been
advised by this writing that:  (a) my waiver and release do not apply to any rights or
claims that may arise after the date I sign this Supplemental Release; (b) I should consult with an attorney prior to signing
this Supplemental Release (although I may choose not to do so); (c) I have twenty-one (21) days to consider this
Supplemental Release (although I may choose to voluntarily sign it earlier); (d) I have seven (7) days following the date I sign this
Supplemental Release to revoke it; and (e) this
Supplemental Release will not be effective until the date upon which the
revocation period has expired, which will be the eighth calendar day after the
date I sign it (the Effective Date). 6 
   I UNDERSTAND THAT THIS AGREEMENT INCLUDES A RELEASE OF
ALL KNOWN AND UNKNOWN CLAIMS.  I
acknowledge that I have read and understand Section 1542 of the California
Civil Code which reads as follows:  A general
release does not extend to claims which the creditor does not know or suspect
to exist in his favor at the time of executing the release, which if known by
him must have materially affected his settlement with the debtor. I hereby expressly waive and relinquish all rights
and benefits under that section and any law of any jurisdiction of similar
effect with respect to my release of any claims I may have. By:
  /s/ Michael
  SchwartzDate:
  April 30, 2003  7 
   Exhibit B PROPRIETARY
INFORMATION AND INVENTIONS AGREEMENT   Pharsight
Corporation  Proprietary Information and
Inventions Agreement  In consideration
of, and as a condition of, my employment with Pharsight
Corporation, a Delaware corporation (the Company), I hereby represent
to and agree with the Company as follows:  1.             Purpose of Agreement; Effective
Date.I understand that the
Company is engaged in a continuous program of research, development,
production, and marketing in connection with its business and that it is
critical for the Company to preserve and protect its Proprietary Information
(as defined below) and its rights in Inventions (as defined below) and all
related intellectual property rights. 
Accordingly, whether or not I am expected to create inventions of value
for the Company, I am entering into this Proprietary Information and Inventions
Agreement (this Agreement) as a condition of my employment with the
Company.  This Agreement shall be
effective as of the first day of my employment with the Company.  2.             Definition of Proprietary
Information.Proprietary
Information is any information of a confidential nature (i.e., not generally
known or publicly available) that may be disclosed to me that relates to the
business of the Company or to the business of any parent, subsidiary,
affiliate, customer, or supplier of the Company or to the business of any other
party with whom the Company agrees to hold the information disclosed by such
party in confidence.   Proprietary
Information includes but is not limited to Inventions, marketing plans, product
plans, business strategies, financial information, forecasts, personnel
information, customer lists, and product sales and pricing information.  3.             Confidentiality.Iunderstand that my
employment by the Company creates a relationship of confidence and trust with
respect to Proprietary Information.  At
all times, both during my employment with the Company and after the termination
of such employment, I will keep and hold all Proprietary Information in confidence
and trust, and I will not use or disclose any Proprietary Information without
the prior written consent of the Company, except as may be necessary to perform
my duties as an employee of the Company for the benefit of the Company.  Upon termination of my employment with the
Company, I will promptly deliver to the Company all documents and materials of
any nature pertaining to my work with the Company, and I will not take with me
any documents or materials or copies thereof containing any Proprietary Information.  4.             Work for Hire.I acknowledge and agree that any copyrightable works
prepared by me within the scope of my employment are works for hire under the
Copyright Act and that the Company will be considered the author and owner of
such copyrightable works.  5.             Definition of Invention.  The term Invention includes all inventions,
improvements, designs, original works of authorship, formulas, processes,
compositions of matter, algorithms, computer software programs, databases, mask
works, and trade secrets that either (a) are developed using equipment,
supplies, facilities or trade secrets of the Company, (b) result from work
performed by me for the Company, or (c) relate to the Companys business or to
its current or anticipated research or development.  6.             Disclosure and Assignment of
Inventions. I will promptly disclose in confidence to the
Company all Inventions that I make or conceive or create or first reduce to
practice, either alone or jointly with others, during the period of my
employment, whether or not in the course of my employment  
     and whether or not
such Inventions are patentable, copyrightable, or protectable as trade
secrets.  I agree that all Inventions
that (a) are developed using equipment, supplies, facilities or trade secrets
of the Company, (b) result from work performed by me for the Company, or (c)
relate to the Companys business or to its current or anticipated research or
development will be the sole and exclusive property of the Company and are
hereby irrevocably assigned by me to the Company.  7.             Assignment of Other Rights.In addition to the foregoing
assignment of Inventions to the Company, I hereby irrevocably transfer and
assign to the Company: (a) all worldwide patents, patent applications,
copyrights, mask works, trade secrets, and any other intellectual property
rights in any and all Inventions, and (b) any and all Other Rights (as defined
below) that I may have in or with respect to any Invention.  I also hereby forever waive and agree never
to assert any Other Rights I may have in or with respect to any Invention, even
after termination of my employment with the Company.  Other Rights means any right to claim authors rights with
respect to an Invention, to object to or prevent the modification of any Invention,
and any similar right, existing under judicial or statutory law of any country
in the world, or under any treaty, regardless of whether such right is
denominated or generally referred to as a moral right or otherwise.  8.             Labor Code Notice.Ihave been notified and
understand that the provisions of paragraphs 6 and 7 of this Agreement do not
apply to any Invention that qualifies fully under the provisions of Section
2870 of the California Labor Code, which states as follows:  Any provision in an employment agreement which provides that an
employee shall assign or offer to assign any of his or her rights in an
invention to his or her employer shall not apply to an invention that the
employee developed entirely on his or her own time without using the employers
equipment, supplies, facilities, or trade secret information except for those
inventions that either: (1) relate at the time of conception or reduction to
practice of the invention to the employers business, or actual or demonstrably
anticipated research or development of the employer, or (2) result from any
work performed by the employee for the employer.  To the extent a provision in an employee agreement purports to
require an employee to assign an invention otherwise excluded from being required
to be assigned under California Labor Code section 2870(a), the provision is
against the public policy of this state and is unenforceable.  9.             Assistance.Iagree to assist the Company in every
proper way to obtain for the Company and to enforce patents, copyrights, mask
work rights, trade secret rights, and other legal protections for the Companys
Inventions in any and all countries.  I
will execute any documents that the Company may reasonably request for use in
obtaining or enforcing such patents, copyrights, mask work rights, trade secret
rights and other legal protections.  My
obligations under this paragraph will continue beyond the termination of my
employment with the Company, provided that the Company will compensate me at a
reasonable rate after such termination for time and expenses actually spent by
me at the Companys request on such assistance.  10.           No Breach of Prior Agreement.Irepresent that my
performance of all the terms of this Agreement and my duties as an employee of
the Company will not breach any invention assignment, proprietary information,
or similar agreement with any former employer or other party. During my
employment by the Company I will not improperly use or disclose any
confidential information or trade secrets, if any, of any former employer or
any other person to whom I have an obligation of   2 
    confidentiality,
and I will not bring onto the premises of the Company any unpublished documents
or any property belonging to any former employer or any other person to whom I
have an obligation of confidentiality unless consented to in writing by that
former employer or person, or unless the items have been legally transferred to
the Company or are generally available to the public.  I will use in the performance of my duties only information which
is generally known and used by persons with training and experience comparable
to my own, which is common knowledge in the industry or otherwise legally in
the public domain, or which is otherwise provided, developed or owned by the
Company.  11.         Prior Inventions.  If, in the course of my employment with the Company, I
incorporate a prior invention made by me into a Company product, process or
machine, the Company is hereby granted and shall have a nonexclusive,
royalty-free, irrevocable, perpetual, worldwide license (with rights to
sublicense through multiple tiers of sublicensees) to make, have made, modify,
use and sell such prior invention. 
Notwithstanding the foregoing, I agree that I will not incorporate, or
permit to be incorporated, prior inventions in any Company Inventions without
the Companys prior written consent.  12.           Notification.Ihereby authorize the Company
to notify my future employers of the terms of this Agreement and my
responsibilities hereunder.  13.           Injunctive Relief.Iunderstand that in the event of a breach
or threatened breach of this Agreement by me, the Company may suffer
irreparable harm and will therefore be entitled to injunctive relief to enforce
this Agreement.  14.           Governing Law; Severability.This Agreement will be governed and interpreted in
accordance with the laws of the State of California, without regard to
application of choice of law rules or principles.  In the event that any provision of this Agreement is found by a
court, arbitrator, or other tribunal to be illegal, invalid, or unenforceable,
then such provision shall not be voided but shall be enforced to the maximum
extent permissible under applicable law, and the remainder of this Agreement
shall remain in full force and effect.  15.           No Duty to Employ.Iunderstand that this Agreement does not
constitute a contract of employment or obligate the Company to employ me for
any stated period of time.  16.           FDA Debarrment.  I represent that I have never been debarred under Section 306(a)
or (b) of the Federal Food Drug or Cosmetic Act and that I will immediately
notify the Company in the event that any debarrment proceedings are commenced
against me.   Pharsight
  Corporation
  
  /s/ Michael J. SchwartzBy
  /s/ Stacy Murphy
  
  November 22, 2000Stacy Murphy
  Date:Vice President, Human
  Resources
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