<PAGE>

                                           *** TEXT OMITTED AND FILED SEPARATELY
                                                CONFIDENTIAL TREATMENT REQUESTED
                                           UNDER 17 C.F.R.SECTIONS 200.80(b)(4),
                                                            200.83 AND 240.24b-2

                                                                   EXHIBIT 10.10

                              PHARSIGHT CORPORATION

                           DATABASE LICENSE AGREEMENT

This Database License Agreement (this "Agreement") is made and entered into as
of February 24, 2000 (the "Effective Date") by and between Pharsight
Corporation, a California corporation, (hereinafter "Pharsight") and Duke
University, a nonprofit educational and healthcare institution (hereinafter
"Duke").

                                    RECITALS

Pharsight is engaged in the sale of software and services relating to clinical
trial design and modeling to pharmaceutical and biotechnology companies and
desires to have the right to use certain databases developed by Duke, through
its Duke Clinical Research Institute, both as a data resource for an
Internet-based query-response product and internally in its professional
consulting practice.

Duke is the owner of or has appropriate licenses to all US and foreign
copyrights and all other intellectual property rights pertaining to the
databases that are the subject of this Agreement and has the right to grant
licenses under such copyrights and other intellectual property rights. Duke
wishes to have these databases utilized in the public interest and is willing to
grant to Pharsight a non-exclusive right and license to use, reproduce, modify,
and create derivatives of the subject database on the terms and conditions set
forth herein.

NOW, THEREFORE, IN CONSIDERATION OF THESE PREMISES, AS WELL AS THE OBLIGATIONS
HEREIN MADE AND UNDERTAKEN, THE PARTIES HERETO DO HEREBY AGREE AS FOLLOW, WITH
THE CAPITALIZED TERMS HAVING THE MEANING SET FORTH IN APPENDIX A:

1. DATABASE DELIVERY, TESTING, AND UPDATES

1.1 DELIVERY OF DATABASES. Duke will perform the statistical extraction of its
patient-level data to create the Databases in accordance with the specifications
in Appendix B and will test the Databases against the Acceptance Criteria. As a
first step, Duke will prepare and deliver to Pharsight electronically within
four (4) weeks of the Effective Date a sample database based on the Databases
that Pharsight can use for testing purposes. The complete Databases will be
delivered within twelve (12) weeks of the Effective Date.

1.2 ACCEPTANCE. Pharsight will have thirty (30) working days from receipt of
each Database to test for adherence to the Acceptance Criteria and will notify
Duke promptly if the Database fails to conform to such criteria. Duke will have
twenty (20) working days to correct such nonconformity, and upon redelivery
Pharsight will again test the Database against the Acceptance Criteria. This
process will be repeated (except that each subsequent test period and repair
period will be limited to fifteen (15)


                                       1
<PAGE>

working days) until Pharsight either provides Duke with written notice of
acceptance of the Database or is deemed to have accepted the Database under the
provisions of this section, provided, however, that if the Database fails to
meet the Acceptance Criteria on the third delivery, Pharsight shall have the
right to terminate this Agreement with respect to that particular Database and
receive a full refund of all payments made to Duke prior to such termination for
the licensing of said Database. Pharsight shall be deemed to have accepted the
Database if it fails to notify Duke of any nonconformity therein within thirty
(30) working days of delivery (or within fifteen (15) working days of redelivery
in the case of nonconformities in the original delivery).

1.3 PATIENT ANONYMITY. The Databases will be totally anonymous as to the
identity of individual patients, the study in which those patients participated,
the sponsors of clinical trials in which data may have been collected, and the
identity of medical practitioners and institutions providing treatment.
Pharsight will not make any attempt to ascertain such information or any other
information that was "confidentialized" by substituting codes for identifying
information before Duke provided the Databases to Pharsight. Pharsight will
promptly notify Duke if it finds that any such information has inadvertently
been included in a Database and will promptly purge such information from the
Database.

1.4 DATA ACCESS. Customers using the Product will have access only to summary
statistics presented in numeric, tabular, and graphical form. The Product will
be constructed so that it is not possible for Customers to access data records
for individual patients or to identify individual practitioners or institutions
providing treatment or the sponsors of clinical trials in which data may have
been collected. Pharsight will maintain sufficient security measures, including
firewalls and secure transmission protocols, to ensure that patient records from
the Databases are always under Pharsight's control and cannot be accessed by its
Customers. Pharsight will provide its consulting services Customers with
tabular, graphical, numerical or narrative results based upon statistical
analysis of data extracted from the Databases by its own consultants. All
results provided to Customers will be in summary and non-patient specific form,
and Pharsight's consultants will not share data from individual patient records
in the Databases with Customers unless required to do so by the FDA.

1.5 UPDATES. During the term of this Agreement, Duke will provide Pharsight with
an Update for each Database within thirty (30) days after the beginning of each
year of this Agreement (including any renewal terms). The Update will be subject
to QA testing in accordance with the criteria established by the parties.

1.6 COSTS. Duke will be fully responsible for all development and extraction
costs of the Databases and any Updates, including any royalties or payments due
to third-parties.

2. GRANT OF LICENSE

2.1 LICENSE GRANT FOR PRODUCT. Subject to the payment of royalties as set forth
in Section 4.2, Duke hereby grants Pharsight a world-wide right and license (a)
to use, reproduce, and modify the Databases and Documentation and to create
Database Derivatives for development of the Product; (b) to license the Product
to its Customers; (c) to license its Customers to use results obtained through
the use of the Product for drug development and marketing activities, including
regulatory submissions and research publications; (d) to use the Databases, the
Documentation, and the Database Derivatives for purposes of technical support
for Customers; and (e) to use a reasonable number of copies of the


                                       2
<PAGE>

Product, Databases, Documentation, and Database Derivatives for purposes of
marketing, training, and demonstrations.

2.2 LICENSE GRANT FOR CONSULTING . Pharsight will have unrestricted access to
data in the Databases and Database Derivatives for use in its consulting
activities and, subject to the royalty obligations of Section 4.3 and other
material terms of this Agreement, Duke hereby grants Pharsight a world-wide
right and license (a) to use the Databases, the Database Derivatives, and the
Documentation to prepare statistical results and conclusions based on data
extracted from the Databases and Database Derivatives under consulting contracts
with Customers; (b) to distribute to such Customers models, other analyses, and
conclusions based on its analysis of the data in the Databases and Database
Derivatives; and (c) to allow such Customers to use such models, analyses, and
conclusions for drug development and marketing activities, including regulatory
submissions and research publications.

2.3 OWNERSHIP. Pharsight acknowledges that the Databases and the underlying data
are, and shall remain, the exclusive property of Duke, that Pharsight has no
rights in such properties except those expressly granted by this Agreement and
that those properties shall not be used in any way not specifically allowed by
this Agreement. Duke acknowledges that Pharsight will own all right, title, and
interest in and to the query, user interface, and other software developed by or
for Pharsight as part of the Product and that Duke has no rights in the Product
except as may be expressly granted by Pharsight. Database Derivatives created by
Pharsight, including but not limited to a loading or other translation of the
Databases from one format to another, shall be owned by Pharsight, but such
ownership of the Database Derivatives shall be subject to Duke's underlying
ownership of the data and shall not give Pharsight any rights to use such
Database Derivatives, to the extent they contain such data, in any way not
authorized by this Agreement. Pharsight will treat any Database Derivative and
the underlying data contained therein with the same care and under the same
restrictions defined in this Agreement.

2.4 LIMITED EXCLUSIVITY. During the term of this Agreement, Duke will not sell
or license either Database to any third party for use in or development of
commercial Internet-based query-response products or services similar to those
provided by Pharsight. This Agreement shall not be taken to place any other
restriction on Duke's rights to license its data to third parties or to use its
data in providing services to third parties. This Agreement shall not be taken
to place any restrictions on Duke's right to use, copy, or modify the Databases
for Duke's research, educational, and healthcare purposes, including in projects
that may be sponsored by commercial third parties, except that Duke will not
make such use in support of any commercial Internet-based query-response
products or services similar to those provided by Pharsight.

2.5 LIMITED LICENSE TO DUKE FOR PRODUCT. Pharsight hereby grants Duke a
royalty-free, non-exclusive license (limited to ten users to be identified by
Duke) to use the Product for Duke's internal research purposes, including
research sponsored by governmental organizations, non-profit foundations, or
through gifts, and for educational and other non-profit purposes, including the
preparation of scientific publications by Duke personnel. Duke will acknowledge
the contribution of Pharsight in any scientific publication resulting from
Duke's use of the Product.

3.  PRODUCT DEVELOPMENT, MARKETING AND DISTRIBUTION

3.1 PRODUCT DEVELOPMENT. Pharsight will develop the query, user interface, and
other software for the Product that will allow licensed Customers to access the
information in the Databases, as described


                                       3
<PAGE>

in the application overview in Appendix B. The target date for commercial
release of the Product is June 2000.

3.2 PRODUCT MARKETING ACTIVITIES. Pharsight will be responsible for all
decisions and costs involved in the marketing and distribution of the Product
and consulting services utilizing the Databases, including pricing, end-user
license terms, promotional materials, packaging, distribution channels, and
customer evaluation and training. Pharsight may distribute the Product through
Distributors so long as such Distributors have no direct access to the
Databases. Pharsight may authorize its Distributors to use the Product for
marketing, training, and demonstrations.

3.3 DATABASE SOURCE IDENTIFICATION. Neither party will, without the prior
written consent of the other party: (a) use in advertising, publicity or
otherwise, the name of any employee or agent, any trade-name, trademark, trade
device, service mark, symbol, or any abbreviation, contraction or simulation
thereof owned by the other party, or (b) represent, either directly or
indirectly, that any product or service of the other party is a product or
service of the representing party. Notwithstanding the foregoing, Pharsight may
identify the Databases as having been prepared by Duke, subject to Duke's
approval of the copy, which shall not be unreasonably withheld. Pharsight will
submit all marketing materials referencing Duke to the Reviewers identified in
Appendix A at the addresses set forth therein at least thirty (30) days prior to
their intended use. Duke shall be deemed to have approved the marketing
materials if it fails to notify Pharsight of any problems therein within thirty
(30) days of submission. Pharsight will not represent or imply that use of the
Databases represents any endorsement of the Product by Duke.

3.4 CUSTOMER SUPPORT. Pharsight will provide customer support for the Product.
Duke will make one or more persons familiar with each Database available to
assist Pharsight personnel in the resolution of problems they may encounter from
time to time in use of the Databases. For each [...*** ...] in royalties paid by
Pharsight to Duke (including the initial payment), Duke will provide one day of
problem resolution assistance to Pharsight personnel without charge; further
assistance will be provided as reasonably necessary at [...***...] per day,
prorated on an hourly basis for usage of less than a full day (minimum charge of
four hours per day).

3.5 PRESS ANNOUNCEMENTS. Pharsight will issue a press release announcing the
relationship between Pharsight and Duke (target release date: ACC Scientific
Session 2000), which announcement shall be subject to approval by Duke. Duke
agrees that it will consider supplying a quotation for the press release. The
parties agree that as further news about the relationship is generated in the
future, they will cooperate with each other to issue appropriate press releases,
subject to prior approval by Duke, to cover such news.

4.  PAYMENTS

4.1 PREPAID ROYALTIES. To allow Duke to cover up-front expenses associated with
the preparation of the Databases, Pharsight will make lump-sum, minimum royalty
payments to Duke as follows:.(a) [...***...] upon execution of this Agreement
and (b) [...***...] upon delivery of the Databases.; To cover the up-front costs
for creating the Updates, Pharsight will make lump-sum,

----------------
* Confidential treatment requested.


                                       4
<PAGE>

minimum royalty payments to Duke as follows: (a) [...*** ...] at the start of
each subsequent year of this Agreement (including any renewal terms); and (d)
[...***...] upon the delivery of the Updates in accordance with Section 1.5. All
of these royalty payments, together with the [...***...] previously paid by
Pharsight in connection with the parties' letter of intent on December 22, 1999,
will be credited against actual royalties due in each year under section 4.2 and
4.3 below. Should the royalties due under sections 4.2 and 4.3 for a year be
less than these minimum payments, then Duke shall be entitled to retain the full
minimum payment.

4.2 PRODUCT ROYALTY. Pharsight will pay Duke a royalty of [...***...] for each
annual Customer subscription license allowing use of the Product. No royalty
will be due for evaluation licenses allowing a Customer limited use of the
Product, provided Pharsight receives no revenue for such evaluation licenses, or
for use of the Product in Customer training programs.

4.3 SERVICE USE ROYALTY. Pharsight will pay Duke a running royalty of
[...***...] of revenues that Pharsight receives for consulting services where
its professional staff utilize the Databases or Database Derivatives. Pharsight
will invoice Customers separately for the portion of such services that utilizes
the Databases or Database Derivatives, and the royalty will be based on the
invoiced amounts. No royalty will be due for use of the Databases or Database
Derivatives for Pharsight staff training.

4.4 PAYMENTS. Royalty payments will be made on a quarterly basis with payment
due thirty (30) days after the end of each calendar quarter for all Product
license revenue received during such quarter and all consulting service revenue
recognizable (under generally accepted accounting principles) during such
quarter. Each payment will be accompanied by a report setting forth the
calculation of such payment amount. Checks shall be made payable to Duke
University (EIN 56 0532129) and sent to the address supplied by Duke. Pharsight
shall be responsible for all taxes (local, state and federal), including all
sales and use taxes, that may now or hereafter be imposed upon this license or
the possession or use of the Databases by Pharsight, provided, however, that
Pharsight shall have no responsibility for any taxes based upon Duke's net
income.

4.5 AUDIT. Pharsight will, upon written request, during normal business hours,
but not more frequently than once each calendar year, provide access for
purposes of audit to pertinent records relating to royalties payable in
connection with the Databases to an independent accounting firm chosen and
compensated (other than on a contingent fee basis) by Duke and reasonably
acceptable to Pharsight. Such accounting firm will be authorized to report to
Duke only the amount of royalties due and payable for the period examined. If
the amount under-reported by Pharsight is equal to or greater than ten percent
(10%) of the total payment due to Duke for the payment period so audited, then
the cost of the audit shall be borne by Pharsight.

4.6 CONFIDENTIALITY. Duke will not disclose to any third party any sales or
customer information received from Pharsight in connection with royalty payments
and will use such information solely for the purpose of carrying out its
obligations under this Agreement. Pharsight will protect the confidentiality of
the Databases and will not disclose the Databases or the information contained
therein to any third party except as expressly allowed by this Agreement.

5.  WARRANTIES; INDEMNIFICATION; LIMITATION OF LIABILITY

----------------
* Confidential treatment requested.


                                       5
<PAGE>

5.1 WARRANTIES. Duke represents and warrants to Pharsight (a) that Duke has all
rights and authority necessary for the grant of rights and licenses effected by
this Agreement; (b) that the data in the Databases were developed in substantial
accordance with Duke's standard medical record-keeping procedures; (c) that all
required consents to use and redistribute the data in the Databases have been
obtained; and (d) that use and distribution of the Databases as authorized
herein will not violate federal or state patient-privacy laws or regulations.
The warranty in clause (d) shall apply to the Databases only on the basis of the
federal or state patient-privacy laws or regulations in effect at the time of
initial delivery of the Databases and to each Update only on the basis of the
federal or state patient-privacy laws or regulations in effect at the time of
delivery of such Update. If Pharsight is required to cancel any Customer license
for the Product because of Duke's breach of one of the foregoing warranties,
Duke will refund to Pharsight any royalties paid with respect to such cancelled
licenses.

5.2 LIMITATIONS OF WARRANTY. THE FOREGOING WARRANTIES ARE THE ONLY WARRANTIES
MADE BY DUKE. ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE, ARE EXPRESSLY DISCLAIMED.

5.3 NON-INFRINGEMENT. Duke represents that to the best of its knowledge the
Databases do not infringe upon any third party copyrights or other intellectual
property rights, and that Duke has obtained all necessary consents to use and
redistribute the data in the Databases as set forth in this agreement. If the
Databases are found to infringe upon any third party rights, Duke agrees, at no
cost to Pharsight to modify the infringing Database to eliminate such
infringement, or if such modification is not practical to refund to Pharsight
any royalties paid with respect to licenses that Pharsight cancels because of
such infringement.

5.4 INDEMNIFICATION. Pharsight will defend, indemnify, and hold Duke harmless
from and against any action or other proceeding brought against Duke arising
from Pharsight's use, reproduction, modification, and creation of derivatives of
the Databases, except where such action arises from negligence or willful
misconduct on the part of Duke or from Duke's breach of the representations and
warranties set forth in Section 5.1. Duke will defend, indemnify, and hold
Pharsight harmless from and against any action or other proceeding brought
against Pharsight to the extent that it is based on (i) Duke's negligence or
willful misconduct; (ii) a claim that any part of the Databases or Documentation
infringes any copyright or patent or incorporates any misappropriated trade
secrets of any third party; or (iii) a claim that use or distribution of the
Databases as authorized herein violates federal or state patient-privacy laws or
regulations or the privacy rights of any patient included in the Databases as
such laws were in effect at the time of delivery of the version of the Database
that is the subject of such claim.

5.5 CONDITIONS OF INDEMNIFICATION. The indemnifying party will pay any and all
costs, damages, and expenses (including but not limited to reasonable attorneys'
fees) incurred by the indemnified party in any action or proceeding requiring
indemnification under section 5.4 (an "Action"). The indemnifying party will
have no obligation as to any Action unless (i) the indemnified party gives it
prompt notice of the Action; (ii) the indemnifying party has sole control of the
defense and settlement of the Action; and (iii) the indemnified party provides
the indemnifying party, at the indemnifying party's expense, with reasonable
assistance in defense and settlement of the Action.

5.6 LIMITATION ON LIABILITY. IN NO EVENT SHALL EITHER PARTY BE LIABLE TO THE
OTHER FOR ANY INDIRECT, CONSEQUENTIAL, SPECIAL OR INCIDENTAL DAMAGES (INCLUDING
DAMAGES FOR LOSS


                                       6
<PAGE>

OF BUSINESS PROFITS, BUSINESS INTERRUPTION, LOSS OF BUSINESS INFORMATION, AND
THE LIKE) ARISING OUT OF THIS AGREEMENT EVEN IF SUCH PARTY HAS BEEN ADVISED OF
THE POSSIBILITY OF SUCH DAMAGES. EXCEPT WITH RESPECT TO THE INDEMNIFICATION
OBLIGATIONS UNDER SECTIONS 5.4 AND 5.5, NEITHER PARTY'S LIABILITY UNDER THIS
AGREEMENT SHALL EXCEED THE AMOUNTS PAID TO DUKE UNDER THIS AGREEMENT. BOTH
PARTIES ACKNOWLEDGE THAT THE FOREGOING LIMITATION REFLECTS A BARGAINED-FOR
ALLOCATION OF RISK AND THAT THE ROYALTIES SET FORTH HEREIN REFLECT SUCH RISK.

6.  TERM AND TERMINATION

6.1 TERM OF AGREEMENT. The initial term of this Agreement will be the period
beginning on the Effective Date of this Agreement and ending on the second
anniversary of the date on which Pharsight accepts (in accordance with Section
2.2) both Databases. This Agreement may be renewed for two successive additional
one-year periods at Pharsight's option and beyond that may be renewed by mutual
agreement of the parties.

6.2 TERMINATION FOR NON-DELIVERY. If Duke fails to deliver both Databases in a
form meeting the Acceptance Criteria within six (6) months of the Effective
Date, then Pharsight shall have the option to terminate this Agreement, return
any copies of the Databases in its possession, and receive from Duke a refund of
all payments made to Duke prior to such termination, except that Duke may retain
such portion of the payments, not to exceed [...*** ...], reflecting the cost of
the statistical database development effort performed by Duke up to the date of
termination under this Section 6.2.

6.3 TERMINATION FOR BREACH. Each party has the right to terminate this Agreement
if the other party has materially breached any obligation herein and such breach
remains uncured for a period of thirty (30) days after written notice thereof is
sent to the other party. Either party may immediately terminate this Agreement
for fraud, willful misconduct, or illegal conduct of the other party upon
written notice of same to that other party.

6.4 EFFECT OF TERMINATION. Upon termination or expiration of this Agreement, all
rights and licenses granted to Pharsight hereunder shall terminate and Pharsight
shall promptly return, or at Duke's election destroy, the Databases and all
copies thereof and shall cease use of any Database Derivatives to the extent
such Database Derivatives contain data from the Databases. Termination will have
no effect on the rights of any Customer to continue to use any information
obtained from the Databases or Database Derivatives prior to such termination in
accordance with its original license for the Product. Notwithstanding any
termination of this Agreement, Duke shall remain entitled to fees owed pursuant
to this Agreement resulting from use of the Databases or license of the Product
prior to termination of this Agreement.

6.5 SURVIVAL. The provisions of Sections 2.3, 3.3, 4.5, 4.6, 5, 6.4, 6.5, 8, and
9 will survive any termination or expiration of this Agreement.

8. MEDIATION AND ARBITRATION

----------------
* Confidential treatment requested.


                                       7
<PAGE>

8.1 MEDIATION. Any dispute arising under this Agreement will be resolved through
a mediation and arbitration approach. The parties agree to select a mutually
agreeable, neutral third party to help them mediate any dispute that arises
under the terms of this Agreement. Costs and fees associated with the mediation
will be shared equally by the parties.

8.2 ARBITRATION. If the mediation is unsuccessful, the parties agree that the
dispute will be decided by binding arbitration under the rules of the American
Arbitration Association through a panel of three arbitrators with each party
nominating one arbitrator who will select the third who shall serve as chairman
of the panel. The decision of the arbitrators will be final and binding on the
parties and may be entered and enforced in any court of competent jurisdiction
by either party. The findings of the arbitration panel may include an award of
reasonable attorney fees, expert witness costs and expenses, and all other
reasonable costs and expenses incurred in connection with the proceedings

9. GENERAL

9.1 NOTICES. Any notice required or permitted hereunder must be in writing, and
will be effective on the date of delivery when delivered personally, the next
business day after dispatch when sent by Federal Express or other recognized
overnight courier service, or the fifth business day after dispatch when sent by
certified mail, postage prepaid, return receipt requested. Notices should be
addressed to the other party at the address shown below or at such other address
as a party may designate by ten days' advance written notice to the other party:

      Pharsight Corporation                        Duke University
      800 West El Camino Real, Suite 200           2400 Pratt Street
      Mountain View, CA  94040                     Room 0311 Terrace Level
      Attention:  Chief Financial Officer          Durham, NC 27705
      Phone: (650) 314-3800                        Attention: Contracts Manager
      Fax: (650) 314-3810                          Phone: (919) 886-6997
                                                   Fax: (919) 668-7009

9.2 ENTIRE AGREEMENT; MODIFICATIONS. This Agreement, including all appendices,
constitutes the entire agreement of the parties with respect to the subject
matter hereof and supersedes all prior representations, proposals, discussions,
and communications, whether oral or in writing. This Agreement may be modified
or amended only by a writing executed by a duly authorized representative of
each party.

9.3 FORCE MAJEURE. Neither party will be liable to the other for any failure or
delay caused by events beyond such party's control, including, without
limitation, sabotage, riots, insurrections, fires, flood, storm, explosions,
war, or earthquakes. However, if such events shall continue for thirty (30) days
or more, the other party shall have the option of terminating this Agreement by
giving written notice of termination.

9.4 CHANGE IN LAW; CHANGE IN CIRCUMSTANCES. No party shall make or receive any
payment or take any action under this Agreement if any judicial decision,
legislative action, or regulatory or other administrative interpretation,
whether federal or state, would render illegal the conduct of either party under
this Agreement. If performance by either party of any term of this Agreement
should be deemed illegal by any party or third party who is essential to
performance of this Agreement for any such reason,


                                       8
<PAGE>

either party shall have the right to require that the other party renegotiate
the terms of this Agreement. If the parties fail to reach an agreement
satisfactory to both parties within fifteen (15) days after the receipt of any
request for renegotiation, either party may terminate this Agreement upon ten
(10) days prior written notice to the other party, or sooner if required by law.

9.5 ASSIGNMENT. This Agreement will be binding upon and inure to the benefit of
the parties hereto, their successors and permitted assigns. Neither party may
assign its rights and obligations under this Agreement to a third party without
the written permission of the other party, except that either party may assign
this Agreement in its entirety to a successor corporation upon notice to the
other party in the event of a merger or an acquisition of all or substantially
all of the assets of the assigning party.

9.6 GOVERNING LAW. All questions concerning the validity, operation,
interpretation, and construction of this Agreement will be governed by and
determined in accordance with the laws of the State of North Carolina, without
regard to its conflict of laws provisions. Application of the United Nations
Convention on Contracts for the International Sale of Goods is specifically
excluded.

9.7 SEVERABILITY. If a court of competent jurisdiction determines that any
provision of this Agreement is invalid, illegal, or otherwise unenforceable,
such provision shall be replaced with a valid, enforceable provision as nearly
as possible in accordance with the stated intention of the parties, while the
remainder of this Agreement shall remain in full force and effect. To the extent
any provision cannot be enforced in accordance with the stated intentions of the
parties, such provision shall be deemed not to be a part of this Agreement.

9.8 COUNTERPARTS. This Agreement may be executed in any number of counterparts,
all of which together will constitute one and the same instrument.

IN WITNESS THEREOF, THE PARTIES HAVE CAUSED THIS AGREEMENT TO BE EXECUTED BY
THEIR RESPECTIVE DULY AUTHORIZED REPRESENTATIVES AS SET FORTH BELOW:

PHARSIGHT CORPORATION                         DUKE UNIVERSITY

By:  /s/ Robin A. Kehoe                       By:  /s/ illegible
   -------------------------------               -------------------------------
Robin A. Kehoe                                Name:
Chief Financial Officer                       Title


                                       9
<PAGE>

                                   APPENDIX A

                                   DEFINITIONS

DATABASE means the either of the cardio-vascular databases described in Appendix
B and all Updates to such databases when and as delivered to Pharsight.

DATABASE DERIVATIVE means any derivative works, modifications, or new
compilations of one or both of the Databases prepared by or on behalf of
Pharsight for use with the Product or in consulting services.

DISTRIBUTOR means a third-party sales and marketing organization contracted by
Pharsight to market and sell Product subscriptions in selected geographic
regions or market segments, provided such organization has been approved by
Duke. Pharsight will notify Duke of the names of its third-party sales
organizations, and Duke shall be deemed to have approved such third parties as
Distributors if it fails to notify Pharsight of its reasons for disapproval
within thirty (30) days of submission.

DOCUMENTATION means any and all materials provided to Pharsight by Duke
describing the features, structure, functions, fields, contents, collection
methods, etc. of the Databases.

CUSTOMER means a customer of Pharsight or of its distributors to whom Pharsight
has licensed the use of the Product or to whom Pharsight has provided consulting
services utilizing the Databases.

ACCEPTANCE CRITERIA means the specifications for the Databases set forth in
Appendix B and the quality requirements for the Databases set forth in Appendix
C or otherwise agreed upon in writing by the parties.

PRODUCT means Pharsight's Internet query-response product utilizing the
Databases or Database Derivatives in the fields of Acute Coronary Syndrome and
Chronic Ischemic CHF, respectively, and all updates, upgrades, and new versions
thereof.

REVIEWER means the person authorized by Duke to approve marketing materials
submitted by Pharsight. The initial Reviewer is Patricia Hodgson, with an
address at 2400 Pratt Street, Room 0311 Terrace Level, Durham, NC 27705 (phone:
919 668-8914) with a copy to be sent to Gilbert Smith, Ph.D., Associate Director
Science and Technology, Duke University Medical Center, Davison Building, Room
M454, DUMC Box 3664, Durham, NC 27715. Duke shall notify Pharsight of changes in
the Reviewer in accordance with section 9.1.

UPDATE means a new version of the Database, consisting of a new statistical
extraction made from the most recent provider database according to the
specifications defined in Appendix B.


                                       10
<PAGE>

                                   APPENDIX B

          SPECIFICATION AND APPLICATION FOR PHARSIGHT/DUKE CV DATABASES

APPLICATION OVERVIEW

The databases are intended for use with the Pharsight Internet query-response
system, which 1) allows users to ask detailed drug development questions, 2)
acts as an intelligent interface to find and extract the relevant information
from the database, 3) performs relevant numerical analysis to produce summary
results, and 4) presents the aggregate results to the users via lists, graphs
and plots. Typical question areas include incidence and statistical
distributions of specific patient characteristics in anonymous patient databases
and determination of the time course of medical condition and status in both
normal aging and pathological disease states. The system and its methods produce
reports that can be used to improve the process of developing new medical
therapeutics, including new drugs, drug delivery systems, and medical devices
and supplies. The system uses secure Internet technology, allowing users to
access the system 24-hours/day.

OUTLINE OF SPECIFICATIONS FOR DATABASES I AND II

The databases will focus on two important applications in the acute
cardiovascular therapeutic area: acute coronary syndrome and chronic ischemic
congestive heart failure.

[...***...]


----------------
* Confidential treatment requested.


                                       11
<PAGE>

                                   APPENDIX C

                               ACCEPTANCE CRITERIA

A. GENERAL

1. Data types (e.g. alpha vs. numeric, etc.) are as described in Appendix B,
"Variable Definitions Acute Coronary Syndrome Database".

2. Value ranges are as described in Appendix B, "Variable Definitions Acute
Coronary Syndrome Database".

3. Missing values are encoded consistently within each field, using definitions
provided by Duke.

B. MISSING DATA

[...***...]

----------------
* Confidential treatment requested.


                                       12