Exhibit
10.49 THIRD AMENDMENT TO THE
LEASE DATED JUNE 11, 1998 BY AND BETWEEN ASSET GROWTH PARTNERS, LTD as LESSOR and PHARSIGHT CORPORATION as LESSEE  This Third Amendment dated January 31, 2003 shall amend the above
referenced agreement, as amended, (the Lease) as follows:  1.As of February 1, 2003 (the Effective Date), the
Lessee shall receive a monthly credit of Thirty-Three Thousand Seven Hundred
Fifty and 00/100 dollars ($33,750.00) through the end of the Lease term, for a
total credit of Two Hundred Seventy Thousand and 00/100 dollars ($270,000.00).  2.Within fifteen (15) days of the Effective Date, the
letter of credit security deposit as described in Section 1.9 of the Lease
shall be returned to Lessee.  Lessor
shall retain the cash security deposit of One Hundred Sixteen Thousand Eight
Hundred and 00/100 dollars ($116,800.00).  3.Lessor shall build out approximately 726 sq. ft. of
office space adjacent to Suite 240, for use by Sublessee, Mobilearia, as shown
in Exhibit A (the Sublessee Expansion Space).  Lessor and Sublessee shall be responsible for any and all costs
associated with such build-out.  4.Lessor shall provide an allowance of $20,228 toward
the cost of Lessees relocation to the approximate 10,114 sq. ft. designated as
the New Pharsight Suite on the attached Exhibit A, said allowance to be given
as a credit against Lessees April 2003 rent.  5.No later than June 15, 2003, Lessee shall vacate the
16,000 sf in the existing Suite 200 (the Vacated Premises) and relocate to
the New Pharsight Suite. Lessee shall surrender possession of Suite 200 to
Lessor and shall leave all furniture, wiring and racking in place in the
existing Suite 200, and title to said furniture, wiring and racking shall
transfer to Lessor as of June 15, 2003. 
In addition, Lessee shall surrender possession of the furniture, wiring
and racking in place in Suite 240.  6.Upon occupation, the New Pharsight Suite shall be
known as Suite 200, and shall be temporarily redefined to be 10,114 rentable
square feet.  The actual final rentable
square footage shall be confirmed upon completion of final build-out and prior
to Lessees occupation of the New Pharsight Suite.  7.Lessor will endeavor to lease the Vacated Premises and
any rent received by Lessor from the time of Lessees vacation of the Vacated
Premises until the expiration of Lessees original Lease term on September 26,
2003 shall be shared equally with Lessee, after deducting the amortized cost of
tenant improvements and lease commissions from rent.  8.As of September 25, 2003, the Premises shall be
redefined to be Suite 200, consisting of approximately 10,114 sq. ft. as
indicated on Exhibit B.  9.The Lease shall be extended for a period of two years,
to expire on September 30, 2005.  10.Rent for the extended term shall be as follows:  9/25/03  9/26/04                                $2.50
sq. ft. 9/26/04  9/30/05                                $2.60
sq. ft.  11.The Base Year during the extended term shall be
revised to be 2004, and Lessees Share of Operating Expense Increase under
Paragraph 1.10 of the Lease shall be revised to be 8.62%.  12.The parties hereby represent that there are no brokers
due a commission in connection with this transaction.  Should either party elect to have representation, then that party
shall be responsible for payment of any leasing commissions due.  13.All other terms and conditions of the Lease shall
remain unchanged.  [SIGNATURE
PAGE TO FOLLOW.]  
    LESSOR:
  
  LESSEE:ASSET
  GROWTH PARTNERS, LTD.
  
  PHARSIGHT
  CORPORATIONA
  California Limited Partnership
  
  a
  Delaware CorporationBy:
  Rees
  Properties, Inc.General
  Partner/s/  Thomas J. Rees
  
  /s/ Charles FaasThomas J. Rees
  
  Charles FaasPresident
  
  Vice President, FinanceDate:
  February 18, 2003
  
  Date:
  March 3, 2003