$3,000,000 Uses in Section 6.7 (Financial Covenants Clause

Section 6.7 (Financial Covenants from Amendment to Loan and Security Agreement

THIS FIFTH AMENDMENT to Loan and Security Agreement (this Amendment) is entered into this 12th day of June, 2006, by and between Silicon Valley Bank (Bank) and Pharsight Corporation, a Delaware corporation (Borrower) whose address is 321 East Evelyn Avenue, 3rd Floor, Mountain View, CA 94041.

Section 6.7 (Financial Covenants. Sub section (ii) of Section 6.7 is hereby deleted and replaced with the following: (ii) Tangible Net Worth (tested quarterly). Beginning with quarter ending June 30, 2006, Borrower shall maintain a minimum Tangible Net Worth in the amount not less than $3,000,000.