EXHIBIT 10.11.1

                                 AMENDMENT NO. 1

This Amendment No. 1 (the "Amendment") to the parties' Data Set License
Agreement dated as of March 1, 2000 is entered into as of April 11, 2000 by and
between Pharsight Corporation, a California corporation, (hereinafter
"Pharsight") and the Lovelace Respiratory Research Institute (hereinafter
"Lovelace").

         WHEREAS, Pharsight and Lovelace have entered into an Agreement dated as
of March 1, 2000 (the "Agreement") whereby the parties agreed on the terms and
conditions under which Lovelace would grant Pharsight the right to use certain
Data Sets in its products; and

         WHEREAS, the parties have determined that certain of the terms and
conditions set forth in the Agreement should be modified;

         NOW, THEREFORE, the parties agree as follows:

1. All capitalized terms used but not defined in this Amendment shall have the
meaning specified therefor in the Agreement. All section and exhibit numbers
refer to sections and exhibits of the Agreement unless otherwise specified.

2. Section 6.4 is hereby amended to read in its entirety as follows:

         6.4 LOSS OF DATA ACCESS. In the event that at any time during the term
         of this Agreement there is a period of at least sixty (60) days in
         which the number of Consortium members having access to data to
         contribute to the Data Set is less than three (3), Lovelace shall so
         notify Pharsight and shall have the option to substitute for the
         missing Consortium member's data, equivalent years of data from one or
         more of the existing Consortium members, and in the event of such
         substitution, all rights and obligations with respect to the Data Set
         shall continue unchanged. In the event that Lovelace is unable to make
         such a substitution or determines not to exercise its option to do so,
         then Lovelace shall so notify Pharsight and shall thereafter have no
         obligation to provide Updates. Pharsight's rights with respect to the
         Data Set shall continue for one year from the date of such notice, but
         the royalties due under Sections 4.2 and 4.3 shall be reduced to fifty
         percent (50%) of the amount set forth in such sections during such
         one-year period.

3. Section 5.2 is hereby amended to read in its entirety as follows:

         5.2 INDEMNIFICATION. Pharsight will defend, indemnify, and hold
         Lovelace harmless from and against any action or other proceeding
         brought against Lovelace arising from Pharsight's use of the Data Set,
         except where such action arises from negligence or willful misconduct
         on the part of Lovelace or from Lovelace's breach of the
         representations and warranties set forth in Section 5.1. Lovelace 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) Lovelace's negligence or willful misconduct; (ii) a
         claim that any part of the Data Set or Documentation infringes any
         copyright or patent or incorporates any misappropriated trade secrets
         of any third party; or (iii) an action arising from Lovelace's breach
         of the warranties set forth in Section 5.1.



4. The first paragraph of Part II.C. of Appendix E is hereby amended to read
in its entirety as follows:

         "The health care data that underlie the Pharsight (PRODUCT/CONSULTING
         SERVICE) are currently derived from two health care organizations that
         are members of the Lovelace Data Consortium. This Consortium was
         created and is managed by the Southwest Center for Managed Care
         Research of the Lovelace Respiratory Research Institute. The
         patient-level data from these two organizations have been merged into
         one combined database. One of the contributing organizations is a
         managed care organization in the southwestern United States. The second
         organization is a network model managed health care plan in the
         mid-Atlantic region of the United States."

5. Except as set forth herein, the Agreement shall remain unmodified and in full
force and effect in accordance with its terms.


IN WITNESS WHEREOF, THE PARTIES HAVE EXECUTED THIS AMENDMENT AS OF THE DATE
FIRST ABOVE WRITTEN.

PHARSIGHT CORPORATION                   LOVELACE RESPIRATORY RESEARCH INSTITUTE


By: /s/ Robin A. Kehoe                  By:   /s/ Patricia J. Marx
   -------------------                     -----------------------
Robin A. Kehoe                          Name:  Patricia J. Marx
Chief Financial Officer                 Title:  Chief Operating Officer




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