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                                                                  Exhibit 10.5


                            LOAN AND SECURITY AGREEMENT
                               PHARSIGHT CORPORATION

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                                  TABLE OF CONTENTS

<TABLE>
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                                                                                 PAGE
<S>                                                                              <C>
1    ACCOUNTING AND OTHER TERMS. . . . . . . . . . . . . . . . . . . . . . . . . . .4

2    LOAN AND TERMS OF PAYMENT . . . . . . . . . . . . . . . . . . . . . . . . . . .4
     2.1  Advances.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
     2.2  Overadvances.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
     2.3  Interest Rate, Payments. . . . . . . . . . . . . . . . . . . . . . . . . .4
     2.4  Fees.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

3    CONDITIONS OF LOANS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
     3.1  Conditions Precedent to Initial Advance. . . . . . . . . . . . . . . . . .5
     3.2  Conditions Precedent to all Advances.. . . . . . . . . . . . . . . . . . .5

4    CREATION OF SECURITY INTEREST . . . . . . . . . . . . . . . . . . . . . . . . .5
     4.1  Grant of Security Interest.. . . . . . . . . . . . . . . . . . . . . . . .5

5    REPRESENTATIONS AND WARRANTIES. . . . . . . . . . . . . . . . . . . . . . . . .5
     5.1  Due Organization and Authorization.. . . . . . . . . . . . . . . . . . . .5
     5.2  Collateral.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
     5.3  Litigation.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
     5.4  No Material Adverse Change in Financial Statements.. . . . . . . . . . . .6
     5.5  Solvency.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
     5.6  Regulatory Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . .6
     5.7  Subsidiaries.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
     5.8  Full Disclosure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

6    AFFIRMATIVE COVENANTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
     6.1  Government Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . .7
     6.2  Financial Statements, Reports, Certificates. . . . . . . . . . . . . . . .7
     6.3  Inventory; Returns.. . . . . . . . . . . . . . . . . . . . . . . . . . . .7
     6.4  Taxes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
     6.5  Insurance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
     6.6  Primary Accounts.. . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
     6.7  Financial Covenants. . . . . . . . . . . . . . . . . . . . . . . . . . . .8
     6.8  Further Assurances.. . . . . . . . . . . . . . . . . . . . . . . . . . . .8

7    NEGATIVE COVENANTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
     7.1  Dispositions.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
     7.2  Changes in Business, Ownership, Management or Business
          Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
     7.3  Mergers or Acquisitions. . . . . . . . . . . . . . . . . . . . . . . . . .9
     7.4  Indebtedness.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
     7.5  Encumbrance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
     7.6  Distributions; Investments.. . . . . . . . . . . . . . . . . . . . . . . .9
     7.7  Transactions with Affiliates.. . . . . . . . . . . . . . . . . . . . . . .9
     7.8  Subordinated Debt. . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
     7.9  Compliance.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

8    EVENTS OF DEFAULT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     8.1  Payment Default. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     8.2  Covenant Default.. . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     8.3  Material Adverse Change. . . . . . . . . . . . . . . . . . . . . . . . . 10

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     8.4  Attachment.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     8.5  Insolvency.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     8.6  Other Agreements.. . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     8.7  Judgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     8.8  Misrepresentations.. . . . . . . . . . . . . . . . . . . . . . . . . . . 11

9    BANK'S RIGHTS AND REMEDIES. . . . . . . . . . . . . . . . . . . . . . . . . . 11
     9.1  Rights and Remedies. . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     9.2  Power of Attorney. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     9.3  Accounts Collection. . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     9.4  Bank Expenses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     9.5  Bank's Liability for Collateral. . . . . . . . . . . . . . . . . . . . . 12
     9.6  Remedies Cumulative. . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     9.7  Demand Waiver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

10   NOTICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

11   CHOICE OF LAW , VENUE AND JURY TRIAL WAIVER . . . . . . . . . . . . . . . . . 12

12   GENERAL PROVISIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     12.1 Successors and Assigns.. . . . . . . . . . . . . . . . . . . . . . . . . 13
     12.2 Indemnification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     12.3 Time of Essence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     12.4 Severability of Provision. . . . . . . . . . . . . . . . . . . . . . . . 13
     12.5 Amendments in Writing, Integration.. . . . . . . . . . . . . . . . . . . 13
     12.6 Counterparts.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     12.7 Survival.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     12.8 Confidentiality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     12.9 Attorneys' Fees, Costs and Expenses. . . . . . . . . . . . . . . . . . . 14

13   DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
               13.1 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . 14

</TABLE>

<PAGE>

       THIS LOAN AND SECURITY AGREEMENT dated January 18, 2000, between
       SILICON VALLEY BANK ("Bank"), whose address is 3003 Tasman Drive,
       Santa Clara, California 95054 and PHARSIGHT CORPORATION
       ("Borrower"), whose address is 800 W. El Camino Real, Suite 200,
       Mountain View, California  94040 provides the terms on which Bank
       will lend to Borrower and Borrower will repay Bank. The parties
       agree as follows:


1      ACCOUNTING AND OTHER TERMS

       Accounting terms not defined in this Agreement will be construed
following GAAP. Calculations and determinations must be made following GAAP.
The term "financial statements" includes the notes and schedules.  The terms
"including" and "includes" always mean "including (or includes) without
limitation," in this or any Loan Document.

2      LOAN AND TERMS OF PAYMENT

2.1    ADVANCES.

       Borrower will pay Bank the unpaid principal amount of all Advances and
interest on the unpaid principal amount of the Advances.

2.1.1  REVOLVING ADVANCES.

       (a)    Bank will make Advances not exceeding the lesser of (A) the
Committed Revolving Line or (B) the Borrowing Base.  Amounts borrowed under this
Section may be repaid and reborrowed without penalty or premium during the term
of this Agreement.

       (b)    To obtain an Advance, Borrower must notify Bank by facsimile or
telephone by 3:00 p.m. Pacific time on the Business Day the Advance is to be
made.  Borrower must promptly confirm the notification by delivering to Bank the
Payment/Advance Form attached as Exhibit B.  Bank will credit Advances to
Borrower's deposit account.  Bank may make Advances under this Agreement based
on instructions from a Responsible Officer or his or her designee or without
instructions if the Advances are necessary to meet Obligations which have become
due.  Bank may rely on any telephone notice given by a person whom Bank
reasonably believes is a Responsible Officer or designee. Borrower will
indemnify Bank for any loss Bank suffers due to such reliance, except for any
loss resulting from Bank's gross negligence or intentional misconduct.

       (c)    The Committed Revolving Line terminates on the Revolving Maturity
Date, when all Advances are immediately payable.

2.2    OVERADVANCES.

       If Borrower's Obligations under Section 2.1.1 exceed the lesser of either
(i)  the Committed Revolving Line or (ii) the Borrowing Base, Borrower must
immediately pay Bank the excess.

2.3    INTEREST RATE, PAYMENTS.

       (a)    Interest Rate.  Advances accrue interest on the outstanding
principal balance at a per annum rate of 1 percentage point above the Prime
Rate.  After and during the continuance of an Event of Default, Obligations
accrue interest at 4 percent above the rate effective immediately before the
Event of Default. The interest rate increases or decreases when the Prime Rate
changes.  Interest is computed on a 360 day year for the actual number of days
elapsed.

       (b)    Payments.  Interest due on the Committed Revolving Line is payable
on the 15th of each month.  Bank may debit any of Borrower's deposit accounts
including Account Number 3300027682 for principal and interest payments owing or
any amounts Borrower owes Bank.  Bank will promptly notify

<PAGE>

Borrower when it debits Borrower's accounts.  These debits are not a set-off.
 Payments received after 12:00 noon Pacific time are considered received at
the opening of business on the next Business Day.  When a payment is due on a
day that is not a Business Day, the payment is due the next Business Day and
additional fees or interest accrue.

2.4    FEES.

       Borrower will pay:

       (a)    Facility Fee.  A fully earned, non-refundable Facility Fee of
$9,750 due on the Closing Date; and

       (b)    Bank Expenses. All Bank Expenses (including reasonable attorneys'
fees and reasonable expenses) incurred through and after the date of this
Agreement, are payable when due.

3      CONDITIONS OF LOANS

3.1    CONDITIONS PRECEDENT TO INITIAL ADVANCE.

       Bank's obligation to make the initial Advance is subject to the condition
precedent that it receive the agreements, documents and fees it requires, as
specified herein.

3.2    CONDITIONS PRECEDENT TO ALL ADVANCES.

       Bank's obligations to make each Advance, including the initial Advance,
is subject to the following:

       (a)    timely receipt of any Payment/Advance Form; and

       (b)    the representations and warranties in Section 5 must be materially
true on the date of the Payment/Advance Form and on the effective date of each
Advance and no Event of Default may have occurred and be continuing, or result
from the Advance. Each Advance is Borrower's representation and warranty on that
date that the representations and warranties of Section 5 remain materially
true.

4      CREATION OF SECURITY INTEREST

4.1    GRANT OF SECURITY INTEREST.

       Borrower grants Bank a continuing security interest in all presently
existing and later acquired Collateral to secure all Obligations and performance
of each of Borrower's duties under the Loan Documents.  Except for Permitted
Liens, any security interest will be a first priority security interest in the
Collateral.  In the event of and during the continuance of an Event of Default,
Bank may place a "hold" on any deposit account pledged as Collateral. If this
Agreement is terminated, Bank's lien and security interest in the Collateral
will continue until Borrower fully satisfies its Obligations.

5      REPRESENTATIONS AND WARRANTIES

       Borrower represents and warrants as follows:

5.1    DUE ORGANIZATION AND AUTHORIZATION.

       Borrower and each Subsidiary is duly existing and in good standing in its
state of formation and qualified and licensed to do business in, and in good
standing in, any state in which the conduct of its business or its ownership of
property requires that it be qualified, except where the failure to do so could
not reasonably be expected to cause a Material Adverse Change.

<PAGE>

       The execution, delivery and performance of the Loan Documents have been
duly authorized, and do not conflict with Borrower's formation documents, nor
constitute an event of default under any material agreement by which Borrower is
bound.  Borrower is not in default under any agreement to which or by which it
is bound in which the default could reasonably be expected to cause a Material
Adverse Change.

5.2    COLLATERAL.

       Borrower has good title to the Collateral, free of Liens except Permitted
Liens.  The Accounts are bona fide, existing obligations, and the service or
property has been performed or delivered to the account debtor or its agent for
immediate shipment to and unconditional acceptance by the account debtor.
Borrower has no notice of any actual or imminent Insolvency Proceeding of any
account debtor whose accounts are an Eligible Account in any Borrowing Base
Certificate.  All Inventory is in all material respects of good and marketable
quality, free from material defects.

5.3    LITIGATION.

       Except as shown in the Schedule, there are no actions or proceedings
pending or, to the knowledge of Borrower's Responsible Officers, threatened by
or against Borrower or any Subsidiary  in which a likely adverse decision could
reasonably be expected to cause a Material Adverse Change.

5.4    NO MATERIAL ADVERSE CHANGE IN FINANCIAL STATEMENTS.

       All consolidated financial statements for Borrower, and any Subsidiary,
delivered to Bank fairly present in all material respects Borrower's
consolidated financial condition and Borrower's consolidated results of
operations.  There has not been any material deterioration in Borrower's
consolidated financial condition since the date of the most recent financial
statements submitted to Bank.

5.5    SOLVENCY.

       The fair salable value of Borrower's assets (including goodwill minus
disposition costs) exceeds the fair value of its liabilities; the Borrower is
not left with unreasonably small capital after the transactions in this
Agreement; and Borrower is able to pay its debts (including trade debts) as they
mature.

5.6    REGULATORY COMPLIANCE.

       Borrower is not an "investment company" or a company "controlled" by an
"investment company" under the Investment Company Act.  Borrower is not engaged
as one of its important activities in extending credit for margin stock (under
Regulations T and U of the Federal Reserve Board of Governors).  Borrower has
complied in all material respects with the Federal Fair Labor Standards Act.
Borrower has not violated any laws, ordinances or rules, the violation of which
could reasonably be expected to cause a Material Adverse Change.  None of
Borrower's or any Subsidiary's properties or assets has been used by Borrower or
any Subsidiary or, to the best of Borrower's knowledge, by previous Persons, in
disposing, producing, storing, treating, or transporting any hazardous substance
other than legally.  Borrower and each Subsidiary have timely filed all required
tax returns and paid, or made adequate provision to pay, all material taxes,
except those being contested in good faith with adequate reserves under GAAP.
Borrower and each Subsidiary have obtained all consents, approvals and
authorizations of, made all declarations or filings with, and given all notices
to, all government authorities that are necessary to continue its business as
currently conducted, except where the failure to do so could not reasonably be
expected to cause a Material Adverse Change.

5.7    SUBSIDIARIES.

       Borrower does not own any stock, partnership interest or other equity
securities except for Permitted Investments.

<PAGE>

5.8    FULL DISCLOSURE.

       No written representation, warranty or other statement of Borrower in any
certificate or written statement given to Bank (taken together with all such
written certificates and written statements to Bank) contains any untrue
statement of a material fact or omits to state a material fact necessary to make
the statements contained in the certificates or statements not misleading.  It
being recognized by Bank that the projections and forecasts provided by Borrower
in good faith and based upon reasonable assumptions are not viewed as facts and
that actual results during the period or periods covered by such projections and
forecasts may differ from the projected and forecasted results.

6      AFFIRMATIVE COVENANTS

       Borrower will do all of the following:

6.1    GOVERNMENT COMPLIANCE.

       Borrower will maintain its and all Subsidiaries' legal existence and good
standing in its jurisdiction of formation and maintain qualification in each
jurisdiction in which the failure to so qualify would reasonably be expected to
cause a material adverse effect on Borrower's business or operations.  Borrower
will comply, and have each Subsidiary comply, with all laws, ordinances and
regulations to which it is subject, noncompliance with which would reasonably be
expected to have a material adverse effect on Borrower's business or operations
or would reasonably be expected to cause a Material Adverse Change.

6.2    FINANCIAL STATEMENTS, REPORTS, CERTIFICATES.

       (a)    Borrower will deliver to Bank:  (i) as soon as available, but no
later than 30 days after the last day of each month, a company prepared
consolidated balance sheet and income statement covering Borrower's consolidated
operations during the period, in a form and certified by a Responsible Officer
reasonably acceptable to Bank; (ii) as soon as available, but no later than 120
days after the last day of Borrower's fiscal year, audited consolidated
financial statements prepared under GAAP, consistently applied, together with an
unqualified opinion on the financial statements from an independent certified
public accounting firm reasonably acceptable to Bank; (iii) a prompt report of
any legal actions pending or threatened against Borrower or any Subsidiary in
which a likely adverse determination could reasonably be expected to result in
damages or costs to Borrower or any Subsidiary of $250,000 or more; and (iv)
promptly, but in no event within 3 Business Days, budgets, sales projections,
operating plans or other financial information as Bank reasonably from time to
time requests.

       (b)    Within 20 days after the last day of each month, Borrower will
deliver to Bank a Borrowing Base Certificate signed by a Responsible Officer in
the form of Exhibit C, with aged listings of accounts receivable and accounts
payable.

       (c)    Within 30 days after the last day of each month, Borrower will
deliver to Bank with the monthly financial statements a Compliance Certificate
signed by a Responsible Officer in the form of Exhibit D.

       (d)    Bank has the right to audit Borrower's Collateral at Borrower's
expense, but the audits will be conducted no more often than every year unless
an Event of Default has occurred and is continuing.

6.3    INVENTORY; RETURNS.

       Borrower will keep all Inventory in good and marketable condition, free
from material defects.  Returns and allowances between Borrower and its account
debtors will follow Borrower's customary

<PAGE>

practices as they exist at execution of this Agreement.  Borrower must
promptly notify Bank of all returns, recoveries, disputes and claims, that
involve more than $50,000.

6.4    TAXES.

       Borrower will make, and cause each Subsidiary to make, timely payment of
all material federal, state, and local taxes or assessments unless contested in
good faith and Borrower has adequate reserve under GAAP and will deliver to
Bank, on demand, appropriate certificates attesting to the payment.

6.5    INSURANCE.

       Borrower will keep its business and the Collateral insured for risks and
in amounts, as Bank may reasonably request.  Insurance policies will be in a
form, with companies, and in amounts that are customary for companies in
Borrower's industry.  All property policies will have a lender's loss payable
endorsement showing Bank as an additional loss payee and all liability policies
will show the Bank as an additional insured and provide that the insurer must
give Bank at least 20 days notice before canceling its policy.  At Bank's
reasonable request, Borrower will deliver certified copies of policies and
evidence of all premium payments. Proceeds payable under any policy will, at
Bank's option, be payable to Bank on account of the Obligations.

6.6    PRIMARY ACCOUNTS.

       Borrower will maintain its primary depository and operating accounts with
Bank.

6.7    FINANCIAL COVENANTS.

       Borrower will maintain as of the last day of each month, unless otherwise
noted:

       (i)    QUICK RATIO (ADJUSTED).  A ratio of Quick Assets to Current
Liabilities minus Deferred Maintenance Revenue of at least 1.80 to 1.00.

       (ii)   QUARTERLY NET INCOME.  Quarterly net income before taxes of not
less than 70% of that approved plan by the Borrower's Board of Directors as
attached hereto by Borrower as Schedule I (to be tested on a quarterly basis).

6.8    FURTHER ASSURANCES.

       Borrower will execute any further instruments and take further action as
Bank reasonably requests to perfect or continue Bank's security interest in the
Collateral or to effect the purposes of this Agreement.

7      NEGATIVE COVENANTS

       Borrower will not do any of the following without Bank's prior written
consent, which will not be unreasonably withheld:

7.1    DISPOSITIONS.

       Convey, sell, lease, transfer or otherwise dispose of (collectively
"Transfer"), or permit any of its Subsidiaries to Transfer, all or any part of
its business or property, other than Transfers (i) of Inventory in the ordinary
course of business; (ii) of non-exclusive licenses and similar arrangements for
the use of the property of Borrower or its Subsidiaries in the ordinary course
of business; or (iii) of worn-out or obsolete Equipment.

<PAGE>

7.2    CHANGES IN BUSINESS, OWNERSHIP, MANAGEMENT OR BUSINESS LOCATIONS.

       Engage in or permit any of its Subsidiaries to engage in any business
other than the businesses currently engaged in by Borrower or reasonably related
thereto or have a material change in its ownership or management (other than the
sale of Borrower's equity securities in a public offering or to venture capital
investors reasonably acceptable to Bank) of greater than 49% Borrower will not,
without at least 30 days prior written notice, relocate its chief executive
office or add any new offices or business locations.

7.3    MERGERS OR ACQUISITIONS.

       Merge or consolidate, or permit any of its Subsidiaries to merge or
consolidate, with any other Person, or acquire, or permit any of its
Subsidiaries to acquire, all or substantially all of the capital stock or
property of another Person, except where (i) no Event of Default has occurred
and is continuing or would result from such action during the term of this
Agreement and (ii) result in a decrease of more than 25% of Tangible Net Worth.
A Subsidiary may merge or consolidate into another Subsidiary or into Borrower.

7.4    INDEBTEDNESS.

       Create, incur, assume, or be liable for any Indebtedness, or permit any
Subsidiary to do so, other than Permitted Indebtedness.

7.5    ENCUMBRANCE.

       Create, incur, or allow any Lien on any of its property, or assign or
convey any right to receive income, including the sale of any Accounts, or
permit any of its Subsidiaries to do so, except for Permitted Liens, or permit
any Collateral not to be subject to the first priority security interest granted
here, subject to Permitted Liens.

7.6    DISTRIBUTIONS; INVESTMENTS.

       Directly or indirectly acquire or own any Person, or make any Investment
in any Person, other than Permitted Investments, or permit any of its
Subsidiaries to do so.  Pay any dividends or make any distribution or payment or
redeem, retire or purchase any capital stock.

7.7    TRANSACTIONS WITH AFFILIATES.

       Directly or indirectly enter or permit any material transaction with any
Affiliate except transactions that are in the ordinary course of Borrower's
business, on terms less favorable to Borrower than would be obtained in an arm's
length transaction with a non-affiliated Person.

7.8    SUBORDINATED DEBT.

       Make or permit any payment on any Subordinated Debt, except under the
terms of the Subordinated Debt, or amend any provision in any document relating
to the Subordinated Debt without Bank's prior written consent, which consent
shall not be unreasonably withheld.

7.9    COMPLIANCE.

       Become an "investment company" or a company controlled by an "investment
company," under the Investment Company Act of 1940 or undertake as one of its
important activities extending credit to purchase or carry margin stock, or use
the proceeds of any Advance for that purpose; fail to meet the minimum funding
requirements of ERISA, permit a Reportable Event or Prohibited Transaction, as
defined in ERISA, to occur; fail to comply with the Federal Fair Labor Standards
Act or violate any other law or regulation, if the violation could reasonable be
expected to have a material adverse effect on Borrower's

<PAGE>

business or operations or would reasonably be expected to cause a Material
Adverse Change, or permit any of its Subsidiaries to do so.

8      EVENTS OF DEFAULT

       Any one of the following is an Event of Default:

8.1    PAYMENT DEFAULT.

       If Borrower fails to pay any of the Obligations within 3 days after their
due date.  During the additional period the failure to cure the default is not
an Event of Default (but no Advance will be made during the cure period);

8.2    COVENANT DEFAULT.

       If Borrower does not perform any obligation in Section 6 or violates any
covenant in Section 7 or does not perform or observe any other material term,
condition or covenant in this Agreement, any Loan Documents, or in any agreement
between Borrower and Bank and as to any default under a term, condition or
covenant that can be cured, has not cured the default within 10 days after it
occurs, or if the default cannot be cured within 10 days or cannot be cured
after Borrower's attempts within 10 day period, and the default may be cured
within a reasonable time, then Borrower has an additional period (of not more
than 30 days) to attempt to cure the default.  During the additional time, the
failure to cure the default is not an Event of Default (but no Advances will be
made during the cure period);

8.3    MATERIAL ADVERSE CHANGE.

       (i) If there occurs a material impairment in the perfection or priority
of the Bank's security interest in the Collateral or in the value of such
Collateral (other than normal depreciation) which is not covered by adequate
insurance or (ii) if the Bank determines, based upon information available to it
and in its reasonable judgment, that there is a reasonable likelihood that
Borrower will fail to comply with one or more of the financial covenants in
Section 6 during the next succeeding financial reporting period.

8.4    ATTACHMENT.

       If any material portion of Borrower's assets is attached, seized, levied
on, or comes into possession of a trustee or receiver and the attachment,
seizure or levy is not removed in 10 days, or if Borrower is enjoined,
restrained, or prevented by court order from conducting a material part of its
business or if a judgment or other claim becomes a Lien on a material portion of
Borrower's assets, or if a notice of lien, levy, or assessment is filed against
any of Borrower's assets by any government agency and not paid within 10 days
after Borrower receives notice.  These are not Events of Default if stayed or if
a bond is posted pending contest by Borrower (but no Advances will be made
during the cure period);

8.5    INSOLVENCY.

       If Borrower becomes insolvent or if Borrower begins an Insolvency
Proceeding or an Insolvency Proceeding is begun against Borrower and not
dismissed or stayed within 45 days (but no Advances will be made before any
Insolvency Proceeding is dismissed);

8.6    OTHER AGREEMENTS.

       If there is a default in any agreement between Borrower and a third party
that gives the third party the right to accelerate any Indebtedness exceeding
$100,000 or that could cause a Material Adverse Change;

<PAGE>

8.7    JUDGMENTS.

       If a money judgment(s) in the aggregate of at least $100,000 is rendered
against Borrower and is unsatisfied and unstayed for 10 days (but no Advances
will be made before the judgment is stayed or satisfied); or

8.8    MISREPRESENTATIONS.

       If Borrower or any Person acting for Borrower makes any material
misrepresentation or material misstatement as of the date made in any warranty
or representation in this Agreement or in any writing delivered to Bank or to
induce Bank to enter this Agreement or any Loan Document.

9      BANK'S RIGHTS AND REMEDIES

9.1    RIGHTS AND REMEDIES.

       When an Event of Default occurs and continues Bank may, without notice or
demand, do any or all of the following:

       (a)    Declare all Obligations immediately due and payable (but if an
Event of Default described in Section 8.5 occurs all Obligations are immediately
due and payable without any action by Bank);

       (b)    Stop advancing money or extending credit for Borrower's benefit
under this Agreement or under any other agreement between Borrower and Bank;

       (c)    Settle or adjust disputes and claims directly with account debtors
for amounts, on terms and in any order that is commercially reasonable and Bank
considers advisable;

       (d)    Make any payments and do any acts it considers necessary or
reasonable to protect its security interest in the Collateral.  Borrower will
assemble the Collateral if Bank requires and make it available as Bank
reasonably designates.  Bank may enter premises where the Collateral is located,
take and maintain possession of any part of the Collateral, and pay, purchase,
contest, or compromise any Lien which appears to be prior or superior to its
security interest and pay all expenses incurred. Borrower grants Bank a license
to enter and occupy any of its premises, without charge, to exercise any of
Bank's rights or remedies;

       (e)    Apply to the Obligations any (i) balances and deposits of Borrower
it holds, or (ii) any amount held by Bank owing to or for the credit or the
account of Borrower;

       (f)    Ship, reclaim, recover, store, finish, maintain, repair, prepare
for sale, advertise for sale, and sell the Collateral; and

       (g)    Dispose of the Collateral according to the Code.

9.2    POWER OF ATTORNEY.

       Effective only when an Event of Default occurs and continues, Borrower
irrevocably appoints Bank as its lawful attorney to:  (i) endorse Borrower's
name on any checks or other forms of payment or security; (ii) sign Borrower's
name on any invoice or bill of lading for any Account or drafts against account
debtors, (iii) make, settle, and adjust all claims under Borrower's insurance
policies; (iv) settle and adjust disputes and claims about the Accounts directly
with account debtors, for amounts and on terms Bank determines reasonable; and
(v) transfer the Collateral into the name of Bank or a third party as the Code
permits.  Bank may exercise the power of attorney to sign Borrower's name on any
documents necessary to perfect or continue the perfection of any security
interest regardless of whether an Event of Default has occurred.  Bank's
appointment as Borrower's attorney in fact, and all of Bank's
<PAGE>

rights and powers, coupled with an interest, are irrevocable until all
Obligations have been fully repaid and performed and Bank's obligation to
provide Advances terminates.

9.3    ACCOUNTS COLLECTION.

       When an Event of Default occurs and continues, Bank may notify any Person
owing Borrower money of Bank's security interest in the funds and verify the
amount of the Account.  Borrower must collect all payments in trust for Bank
and, if requested by Bank, immediately deliver the payments to Bank in the form
received from the account debtor, with proper endorsements for deposit.

9.4    BANK EXPENSES.

       If Borrower fails to pay any amount or furnish any required proof of
payment to third persons, Bank may make all or part of the payment or obtain
insurance policies required in Section 6.5, and take any action under the
policies Bank deems prudent in its reasonable judgement.  Any amounts paid by
Bank are Bank Expenses and immediately due and payable, bearing interest at the
then applicable rate and secured by the Collateral.  No payments by Bank are
deemed an agreement to make similar payments in the future or Bank's waiver of
any Event of Default.

9.5    BANK'S LIABILITY FOR COLLATERAL.

       If Bank complies with reasonable banking practices and Section 9-207 of
the Code, it is not liable for: (a) the safekeeping of the Collateral; (b) any
loss or damage to the Collateral; (c) any diminution in the value of the
Collateral; or (d) any act or default of any carrier, warehouseman, bailee, or
other person.  Borrower bears all risk of loss, damage or destruction of the
Collateral when in Borrower's control and possession.

9.6    REMEDIES CUMULATIVE.

       Bank's rights and remedies under this Agreement, the Loan Documents, and
all other agreements are cumulative.  Bank has all rights and remedies provided
under the Code, by law, or in equity. Bank's exercise of one right or remedy is
not an election, and Bank's waiver of any Event of Default is not a continuing
waiver. Bank's delay is not a waiver, election, or acquiescence. No waiver is
effective unless signed by Bank and then is only effective for the specific
instance and purpose for which it was given.

9.7    DEMAND WAIVER.

       Borrower waives demand, notice of default or dishonor, notice of payment
and nonpayment, notice of any default, nonpayment at maturity, release,
compromise, settlement, extension, or renewal of accounts, documents,
instruments, chattel paper, and guarantees held by Bank on which Borrower is
liable.

10     NOTICES

       All notices or demands by any party about this Agreement or any other
related agreement must be in writing and be personally delivered or sent by an
overnight delivery service, by certified mail, postage prepaid, return receipt
requested, or by telefacsimile to the addresses set forth at the beginning of
this Agreement.  A party may change its notice address by giving the other party
written notice.

11     CHOICE OF LAW , VENUE AND JURY TRIAL WAIVER

       California law governs the Loan Documents without regard to principles of
conflicts of law.  Borrower and Bank each submit to the exclusive jurisdiction
of the State and Federal courts in Santa Clara County, California.
<PAGE>

BORROWER AND BANK EACH WAIVE THEIR RIGHT TO A JURY TRIAL OF ANY CLAIM OR CAUSE
OF ACTION ARISING OUT OF ANY OF THE LOAN DOCUMENTS OR ANY CONTEMPLATED
TRANSACTION, INCLUDING CONTRACT, TORT, BREACH OF DUTY AND ALL OTHER CLAIMS. THIS
WAIVER IS A MATERIAL INDUCEMENT FOR BOTH PARTIES TO ENTER INTO THIS AGREEMENT.
EACH PARTY HAS REVIEWED THIS WAIVER WITH ITS COUNSEL.

12     GENERAL PROVISIONS

12.1   SUCCESSORS AND ASSIGNS.

       This Agreement binds and is for the benefit of the successors and
permitted assigns of each party.  Borrower may not assign this Agreement or any
rights under it without Bank's prior written consent which may be granted or
withheld in Bank's discretion.  Bank has the right, without the consent of or
notice to Borrower, to sell, transfer, negotiate, or grant participation in all
or any part of, or any interest in, Bank's obligations, rights and benefits
under this Agreement.

12.2   INDEMNIFICATION.

       Borrower will indemnify, defend and hold harmless Bank and its officers,
employees, and agents against:  (a) all obligations, demands, claims, and
liabilities asserted by any other party in connection with the transactions
contemplated by the Loan Documents; and (b) all losses or Bank Expenses
incurred, or paid by Bank from, following, or consequential to transactions
between Bank and Borrower (including reasonable attorneys fees and expenses),
except, with respect to (a) and (b) above, for losses caused by Bank's gross
negligence or willful misconduct.

12.3   TIME OF ESSENCE.

       Time is of the essence for the performance of all obligations in this
Agreement.

12.4   SEVERABILITY OF PROVISION.

       Each provision of this Agreement is severable from every other provision
in determining the enforceability of any provision.

12.5   AMENDMENTS IN WRITING, INTEGRATION.

       All amendments to this Agreement must be in writing and signed by
Borrower and Bank.  This Agreement represents the entire agreement about this
subject matter, and supersedes prior negotiations or agreements.  All prior
agreements, understandings, representations, warranties, and negotiations
between the parties about the subject matter of this Agreement merge into this
Agreement and the Loan Documents.

12.6   COUNTERPARTS.

       This Agreement may be executed in any number of counterparts and by
different parties on separate counterparts, each of which, when executed and
delivered, are an original, and all taken together, constitute one Agreement.

12.7   SURVIVAL.

       All covenants, representations and warranties made in this Agreement
continue in full force while  any Obligations remain outstanding.  The
obligations of Borrower in Section 12.2 to indemnify Bank will survive until all
statutes of limitations for actions that may be brought against Bank have run.
<PAGE>

12.8   CONFIDENTIALITY.

       In handling any confidential information, Bank will exercise the same
degree of care that it exercises for its own proprietary information, but
disclosure of information may be made (i) to Bank's subsidiaries or affiliates
in connection with their business with Borrower, (ii) to prospective transferees
or purchasers of any interest in the loans, (iii) as required by law,
regulation, subpoena, or other order, (iv) as required in connection with Bank's
examination or audit and (v) as Bank reasonably considers appropriate exercising
remedies under this Agreement.  Confidential information does not include
information that either: (a) is in the public domain or in Bank's possession
when disclosed to Bank, or becomes part of the public domain after disclosure to
Bank; or (b) is disclosed to Bank by a third party, if Bank does not know that
the third party is prohibited from disclosing the information.

12.9   ATTORNEYS' FEES, COSTS AND EXPENSES.

       In any action or proceeding between Borrower and Bank arising out of the
Loan Documents, the prevailing party will be entitled to recover its reasonable
attorneys' fees and other reasonable costs and expenses incurred, in addition to
any other relief to which it may be entitled.

13     DEFINITIONS

13.1   DEFINITIONS.

       In this Agreement:

       "ACCOUNTS" are all existing and later arising accounts, contract rights,
and other obligations owed Borrower in connection with its sale or lease of
goods (including licensing software and other technology) or provision of
services, all credit insurance, guaranties, other security and  all merchandise
returned or reclaimed by Borrower and Borrower's Books relating to any of the
foregoing.

       "ADVANCE" or "ADVANCES" is a loan advance (or advances) under the
Committed Revolving Line.

       "AFFILIATE" of a Person is a Person that owns or controls directly or
indirectly the Person, any Person that controls or is controlled by or is under
common control with the Person, and each of that Person's senior executive
officers, directors, partners and, for any Person that is a limited liability
company, that Person's managers and members.

       "BANK EXPENSES" are all audit fees and expenses and reasonable costs and
expenses (including reasonable attorneys' fees and expenses) for preparing,
negotiating, administering, defending and enforcing the Loan Documents
(including appeals or Insolvency Proceedings).

       "BORROWER'S BOOKS" are all Borrower's books and records including
ledgers, records regarding Borrower's assets or liabilities, the Collateral,
business operations or financial condition and all computer programs or discs or
any equipment containing the information.

       "BORROWING BASE" is 80% of Eligible Accounts as determined by Bank from
Borrower's most recent Borrowing Base Certificate.

       "BUSINESS DAY" is any day that is not a Saturday, Sunday or a day on
which the Bank is closed.

       "CLOSING DATE" is the date of this Agreement.

       "CODE" is the California Uniform Commercial Code.

       "COLLATERAL" is the property described on EXHIBIT A.
<PAGE>

       "COMMITTED REVOLVING LINE" is an Advance of up to $1,500,000.

       "CONTINGENT OBLIGATION" is, for any Person, any direct or indirect
liability, contingent or not, of that Person for (i) any indebtedness, lease,
dividend, letter of credit or other obligation of another such as an obligation
directly or indirectly guaranteed, endorsed, co-made, discounted or sold with
recourse by that Person, or for which that Person is directly or indirectly
liable; (ii) any obligations for undrawn letters of credit for the account of
that Person; and (iii) all obligations from any interest rate, currency or
commodity swap agreement, interest rate cap or collar agreement, or other
agreement or arrangement designated to protect a Person against fluctuation in
interest rates, currency exchange rates or commodity prices;  but "Contingent
Obligation" does not include endorsements in the ordinary course of business.
The amount of a Contingent Obligation is the stated or determined amount of the
primary obligation for which the Contingent Obligation is made or, if not
determinable, the maximum reasonably anticipated liability for it determined by
the Person in good faith; but the amount may not exceed the maximum of the
obligations under the guarantee or other support arrangement.

       "CURRENT LIABILITIES" are the aggregate amount of Borrower's Total
Liabilities which mature within one (1) year.

       "DEFERRED MAINTENANCE REVENUE" is all amounts received in advance of
performance under maintenance contract and not yet recognized as revenue.

       "ELIGIBLE ACCOUNTS" are Accounts in the ordinary course of Borrower's
business that meet all Borrower's representations and warranties in Section 5;
BUT Bank may change eligibility standards by giving Borrower notice.  Unless
Bank agrees otherwise in writing, Eligible Accounts will not include:

       (a)    Accounts that the account debtor has not paid within 90 days (60
       days for Foreign Accounts as defined in (e) below) of invoice date;

       (b)    Accounts for an account debtor, 50% or more of whose Accounts have
       not been paid within 90 days of invoice date;

       (c)    Credit balances over 90 days from invoice date;

       (d)    Accounts for an account debtor, including Affiliates, whose total
       obligations to Borrower exceed 25% of all Accounts, for the amounts that
       exceed that percentage, unless the Bank approves in writing;

       (e)    Accounts for which the account debtor does not have its principal
       place of business in the United States ("Foreign Accounts"), which in the
       aggregate exceed 35% of total Accounts;

       (f)    Accounts for which the account debtor is a federal, state or local
       government entity or any department, agency, or instrumentality;

       (g)    Accounts for which Borrower owes the account debtor, but only up
       to the amount owed (sometimes called "contra" accounts, accounts payable,
       customer deposits or credit accounts);

       (h)    Accounts for demonstration or promotional equipment, or in which
       goods are consigned, sales guaranteed, sale or return, sale on approval,
       bill and hold, or other terms if account debtor's payment may be
       conditional;

       (i)    Accounts for which the account debtor is Borrower's Affiliate,
       officer, employee, or agent;

       (j)    Accounts in which the account debtor disputes liability or makes
       any claim and Bank believes there may be a basis for dispute (but only up
       to the disputed or claimed amount), or if the Account Debtor is subject
       to an Insolvency Proceeding, or becomes insolvent, or goes out of
       business;
<PAGE>

       (k)    Accounts for which Bank reasonably determines  collection to be
       doubtful.

       "EQUIPMENT" is all present and future machinery, equipment, tenant
improvements, furniture, fixtures, vehicles, tools, parts and attachments in
which Borrower has any interest.

       "ERISA" is the Employment Retirement Income Security Act of 1974, and its
regulations.

       "GAAP" is generally accepted accounting principles.

       "INDEBTEDNESS" is (a) indebtedness for borrowed money or the deferred
price of property or services, such as reimbursement and other obligations for
surety bonds and letters of credit, (b) obligations evidenced by notes, bonds,
debentures or similar instruments, (c) capital lease obligations and (d)
Contingent Obligations.

       "INSOLVENCY PROCEEDING" are proceedings by or against any Person under
the United States Bankruptcy Code, or any other bankruptcy or insolvency law,
including assignments for the benefit of creditors, compositions, extensions
generally with its creditors, or proceedings seeking reorganization,
arrangement, or other relief.

       "INVENTORY" is present and future inventory in which Borrower has any
interest, including merchandise, raw materials, parts, supplies, packing and
shipping materials, work in process and finished products intended for sale or
lease or to be furnished under a contract of service, of every kind and
description now or later owned by or in the custody or possession, actual or
constructive, of Borrower, including inventory temporarily out of its custody or
possession or in transit and including returns on any accounts or other proceeds
(including insurance proceeds) from the sale or disposition of any of the
foregoing and any documents of title.

       "INVESTMENT" is any beneficial ownership of (including stock, partnership
interest or other securities) any Person, or any loan, advance or capital
contribution to any Person.

       "LIEN" is a mortgage, lien, deed of trust, charge, pledge, security
interest or other encumbrance.

       "LOAN DOCUMENTS" are, collectively, this Agreement, any note, or notes or
guaranties executed by Borrower or Guarantor, and any other present or future
agreement between Borrower and/or for the benefit of Bank in connection with
this Agreement, all as amended, extended or restated.

       "MATERIAL ADVERSE CHANGE" is defined in Section 8.3.

       "OBLIGATIONS" are debts, principal, interest, Bank Expenses and other
amounts Borrower owes Bank now or later, including cash management services,
letters of credit and foreign exchange contracts, if any and including interest
accruing after Insolvency Proceedings begin and debts, liabilities, or
obligations of Borrower assigned to Bank.

       "PERMITTED INDEBTEDNESS" is:

       (a)    Borrower's indebtedness to Bank under this Agreement or any other
Loan Document;

       (b)    Indebtedness existing on the Closing Date and shown on the
Schedule;

       (c)    Subordinated Debt;

       (d)    Indebtedness to trade creditors incurred in the ordinary course of
business;

       (e)    Indebtedness secured by Permitted Liens;
<PAGE>

       (f)    Other Indebtedness of Borrower, not exceeding $100,000 in the
aggregate at any time outstanding; and

       (g)    Extensions, renewals, refunding, refinancing, modifications,
amendments and restatements of the items of Permitted Indebtedness (a) through
(e) above, provided that the principal amount thereof is not increased or the
terms thereof are not modified to impose more burdensome terms on the Borrower.

       "PERMITTED INVESTMENTS" are:

       (a)    Investments shown on the Schedule and existing on the Closing
Date; and

       (b)    (i)  marketable direct obligations issued or unconditionally
guaranteed by the United States or its agency or any State maturing within 1
year from its acquisition, (ii) commercial paper maturing no more than 1 year
after its creation and having the highest rating from either Standard & Poor's
Corporation or Moody's Investors Service, Inc., and (iii) Bank's certificates of
deposit issued maturing no more than 1 year after issue; and

       (c)    Other Investments not exceeding $250,000 in the aggregate at any
time.

       "PERMITTED LIENS" are:

       (a)    Liens existing on the Closing Date and shown on the Schedule or
arising under this Agreement or other Loan Documents;

       (b)    Liens for taxes, fees, assessments or other government charges or
levies, either not delinquent or being contested in good faith and for which
Borrower maintains adequate reserves on its Books, IF they have no priority over
any of Bank's security interests;

       (c)    Purchase money Liens (i) on Equipment acquired or held by Borrower
or its Subsidiaries incurred for financing the acquisition of the Equipment, or
(ii) existing on equipment when acquired, IF the Lien is confined to the
property and improvements and the proceeds of the equipment;

       (d)    Leases or subleases and licenses or sublicenses granted in the
ordinary course of Borrower's business and any interest or title of a lessor,
licensor or under any lease or license, IF the leases, subleases, licenses and
sublicenses permit granting Bank a security interest;

       (e)    Liens incurred in the extension, renewal or refinancing of the
indebtedness secured by Liens described in (a) through (c), BUT any extension,
renewal or replacement Lien must be limited to the property encumbered by the
existing Lien and the principal amount of the indebtedness may not increase.

       "PERSON" is any individual, sole proprietorship, partnership, limited
liability company, joint venture, company association, trust, unincorporated
organization, association, corporation, institution, public benefit corporation,
firm, joint stock company, estate, entity or government agency.

       "PRIME RATE" is Bank's most recently announced "prime rate," even if it
is not Bank's lowest rate.

       "QUICK ASSETS" is, on any date, the Borrower's consolidated, unrestricted
cash, plus accounts receivable.

       "RESPONSIBLE OFFICER" is each of the Chief Executive Officer, the
President, the Chief Financial Officer and the Controller of Borrower.

       "REVOLVING MATURITY DATE" is January 18, 2001.
<PAGE>

       "SCHEDULE" is any attached schedule of exceptions.

       "SUBORDINATED DEBT" is debt incurred by Borrower subordinated to
Borrower's debt to Bank (and identified as subordinated by Borrower and Bank).

       "SUBSIDIARY" is for any Person, or any other business entity of which
more than 50% of the voting stock or other equity interests is owned or
controlled, directly or indirectly, by the Person or one or more Affiliates of
the Person.

       "TANGIBLE NET WORTH" is, on any date, the consolidated total assets of
Borrower and its Subsidiaries MINUS, (i) any amounts attributable to (a)
goodwill, (b) intangible items such as unamortized debt discount and expense,
Patents, trade and service marks and names, Copyrights and research and
development expenses except prepaid expenses, and (c) reserves not already
deducted from assets, AND (ii) Total Liabilities.

       "TOTAL LIABILITIES" is on any day, obligations that should, under GAAP,
be classified as liabilities on Borrower's consolidated balance sheet, including
all Indebtedness, and current portion Subordinated Debt allowed to be paid, but
excluding all other Subordinated Debt.


BORROWER:

PHARSIGHT CORPORATION


By: /s/ Robin A. Kehoe
    -----------------------------------

Title:    CFO
       --------------------------------


BANK:

SILICON VALLEY BANK


By: /s/ R. Bryan Jadot
    -----------------------------------

Title:    AVP
       --------------------------------


<PAGE>


                                   EXHIBIT A

       The Collateral consists of all of Borrower's right, title and interest in
and to the following:

       All goods and equipment now owned or hereafter acquired, including,
without limitation, all machinery, fixtures, vehicles (including motor vehicles
and trailers), and any interest in any of the foregoing, and all attachments,
accessories, accessions, replacements, substitutions, additions, and
improvements to any of the foregoing, wherever located;

       All inventory, now owned or hereafter acquired, including, without
limitation, all merchandise, raw materials, parts, supplies, packing and
shipping materials, work in process and finished products including such
inventory as is temporarily out of Borrower's custody or possession or in
transit and including any returns upon any accounts or other proceeds, including
insurance proceeds, resulting from the sale or disposition of any of the
foregoing and any documents of title representing any of the above;

       All contract rights and general intangibles now owned or hereafter
acquired, including, without limitation, goodwill, trademarks, servicemarks,
trade styles, trade names, patents, patent applications, leases, license
agreements, franchise agreements, blueprints, drawings, purchase orders,
customer lists, route lists, infringements, claims, computer programs, computer
discs, computer tapes, literature, reports, catalogs, design rights, income tax
refunds, payments of insurance and rights to payment of any kind;

       All now existing and hereafter arising accounts, contract rights,
royalties, license rights and all other forms of obligations owing to Borrower
arising out of the sale or lease of goods, the licensing of technology or the
rendering of services by Borrower, whether or not earned by performance, and any
and all credit insurance, guaranties, and other security therefor, as well as
all merchandise returned to or reclaimed by Borrower;

       All documents, cash, deposit accounts, securities, securities
entitlements, securities accounts, investment property, financial assets,
letters of credit, certificates of deposit, instruments and chattel paper now
owned or hereafter acquired and Borrower's Books relating to the foregoing;

       All copyright rights, copyright applications, copyright registrations and
like protections in each work of authorship and derivative work thereof, whether
published or unpublished, now owned or hereafter acquired; all trade secret
rights, including all rights to unpatented inventions, know-how, operating
manuals, license rights and agreements and confidential information, now owned
or hereafter acquired; all mask work or similar rights available for the
protection of semiconductor chips, now owned or hereafter acquired; all claims
for damages by way of any past, present and future infringement of any of the
foregoing; and

       All Borrower's Books relating to the foregoing and any and all claims,
rights and interests in any of the above and all substitutions for, additions
and accessions to and proceeds thereof.

       Notwithstanding the foregoing, the Collateral shall not be deemed to
include any copyrights, copyright applications, copyright registration and
like protection in each work of authorship and derivative work thereof,
whether published or unpublished, now owned or hereafter acquired; any
patents, patent applications and like protections including without
limitation improvements, divisions, continuations, renewals, reissues,
extensions and continuations-in-part of the same, trademarks, servicemarks
and applications therefor, whether registered or not, and the goodwill of the
business of Borrower connected with and symbolized by such trademarks, any
trade secret rights, including any rights to unpatented inventions, know-how,
operating manuals, license rights and agreements and confidential
information, now owned or hereafter acquired; or any claims for damage by way
of any past, present and future infringement of any of the foregoing
(collectively, the "Intellectual Property"), except that the Collateral shall
include the proceeds of all the Intellectual Property that are accounts,
(i.e. accounts receivable) of Borrower, or general intangibles consisting of
rights to payment, if a judicial authority (including a U.S. Bankruptcy
Court) holds that a security interest in the underlying Intellectual Property
is necessary to have a security interest in such accounts and general
intangibles of Borrower that are proceeds of the Intellectual Property, then
the Collateral shall automatically, and effective as of the Closing Date,
include the Intellectual Property to the extent necessary to permit
perfection of Bank's security interest in such accounts and general
intangibles of Borrower that are proceeds of the Intellectual Property.
<PAGE>


                                      EXHIBIT B

                     LOAN PAYMENT/ADVANCE TELEPHONE REQUEST FORM

                DEADLINE FOR SAME DAY PROCESSING IS 3:00 P.M., P.S.T.


TO: CENTRAL CLIENT SERVICE DIVISION       DATE:
                                               -----------------------

FAX#:  (408) 496-2426                     TIME:
                                               -----------------------

------------------------------------------------------------------------------
FROM:  Pharsight Corporation
       -----------------------------------------------------------------------
                                CLIENT NAME (BORROWER)

REQUESTED BY:
             -----------------------------------------------------------------
                                AUTHORIZED SIGNER'S NAME

AUTHORIZED SIGNATURE:
                     ---------------------------------------------------------

PHONE NUMBER:
             -----------------------------------------------------------------

FROM ACCOUNT #                  TO ACCOUNT #
              ----------------              ----------------------------------

<TABLE>
<CAPTION>
REQUESTED TRANSACTION TYPE              REQUESTED DOLLAR AMOUNT
<S>                                     <C>
PRINCIPAL INCREASE (ADVANCE)            $
                                         -------------------------------------
PRINCIPAL PAYMENT (ONLY)                $
                                         -------------------------------------
INTEREST PAYMENT (ONLY)                 $
                                         -------------------------------------
PRINCIPAL AND INTEREST (PAYMENT)        $
                                         -------------------------------------
</TABLE>

OTHER INSTRUCTIONS:
                   -----------------------------------------------------------
------------------------------------------------------------------------------
All Borrower's representations and warranties in the Loan and Security
Agreement are true, correct and complete in all material respects on the date
of the telephone request for and Advance confirmed by this Borrowing
Certificate; but those representations and warranties expressly referring to
another date shall be true, correct and complete in all material respects as
of that date.
------------------------------------------------------------------------------
------------------------------------------------------------------------------
                                 BANK USE ONLY

TELEPHONE REQUEST:

The following person is authorized to request the loan payment transfer/loan
advance on the advance designated account and is known to me.

---------------------------------------      ---------------------------------
     Authorized Requester                             Phone #

---------------------------------------      ---------------------------------
     Received By (Bank)                               Phone #


               -------------------------------------------------------
                             Authorized Signature (Bank)

------------------------------------------------------------------------------
<PAGE>

                                      EXHIBIT C
                              BORROWING BASE CERTIFICATE

------------------------------------------------------------------------------
Borrower:     Pharsight Corporation          Bank:     Silicon Valley Bank
                                                       3003 Tasman Drive
                                                       Santa Clara, CA 95054
Commitment Amount:  $1,500,000
------------------------------------------------------------------------------

<TABLE>
<S>                                                              <C>                      <C>
ACCOUNTS RECEIVABLE
1.   Accounts Receivable Book Value as of                                                 $_________
2.   Additions (please explain on reverse)                                                $_________
3.   TOTAL ACCOUNTS RECEIVABLE                                                            $_________

ACCOUNTS RECEIVABLE DEDUCTIONS (without duplication)
4.   Amounts over 90 days due (60 days for Foreign Accounts)     $_________
5.   Balance of 50% over 90 day accounts                         $_________
6.   Credit balances over 90 days                                $_________
7.   Concentration Limits                                        $_________
8.   Foreign Accounts*                                           $_________
9.   Governmental Accounts                                       $_________
10.  Contra Accounts                                             $
11.  Promotion or Demo Accounts                                  $_________
12.  Intercompany/Employee Accounts                              $_________
13.  Other (please explain on reverse)                           $_________
14.  TOTAL ACCOUNTS RECEIVABLE DEDUCTIONS                                                 $_________
15.  Eligible Accounts (#3 minus #14)                                                     $_________
16.  LOAN VALUE OF ACCOUNTS (80% of #15)                                                  $_________
*in excess of  35% of the total Accounts.

BALANCES
17.  Maximum Loan Amount                                         $_________
18.  Total Funds Available:  Lesser of #17 or #16                                         $_________
19.  Present balance owing on Line of Credit                     $_________
20.  Outstanding under Sublimits ( none )                        $_________
21.  RESERVE POSITION (#18 minus #19 and #20)                                             $_________
</TABLE>

THE UNDERSIGNED REPRESENTS AND WARRANTS THAT THIS IS TRUE, COMPLETE AND CORRECT,
AND THAT THE INFORMATION IN THIS BORROWING BASE CERTIFICATE COMPLIES WITH THE
REPRESENTATIONS AND WARRANTIES IN THE LOAN AND SECURITY AGREEMENT BETWEEN THE
UNDERSIGNED AND SILICON VALLEY BANK.

COMMENTS:

                                        _________________________

                                              BANK USE ONLY

                                        Rec'd By:____________
                                                 Auth. Signer

Pharsight Corporation                   Date:________________

                                        Verified:____________
By:____________________________                  Auth. Signer
     Authorized Signer
                                        Date:________________

                                        _____________________
                                        _________________________
<PAGE>



                                  EXHIBIT D
                           COMPLIANCE CERTIFICATE


TO:       SILICON VALLEY BANK
          3003 Tasman Drive
          Santa Clara, CA 95054

FROM:     PHARSIGHT CORPORATION


     The undersigned authorized officer of Pharsight Corporation ("Borrower")
certifies that under the terms and conditions of the Loan and Security
Agreement between Borrower and Bank (the "Agreement"), (i) Borrower is in
complete compliance for the period ending _______________ with all required
covenants except as noted below and (ii) all representations and warranties
in the Agreement are true and correct in all material respects on this date.
Attached are the required documents supporting the certification.  The
Officer certifies that these are prepared in accordance with Generally
Accepted Accounting Principles (GAAP) consistently applied from one period to
the next except as explained in an accompanying letter or footnotes.  The
Officer acknowledges that no borrowings may be requested at any time or date
of determination that Borrower is not in compliance with any of the terms of
the Agreement, and that compliance is determined not just at the date this
certificate is delivered.

 PLEASE INDICATE COMPLIANCE STATUS BY CIRCLING YES/NO UNDER "COMPLIES" COLUMN.

<TABLE>
<CAPTION>
     REPORTING COVENANT                                          REQUIRED                   COMPLIES
     <S>                                                         <C>                        <C>  <C>
     Monthly financial statements + CC                           Monthly within 30 days     Yes  No
     Annual (Audited)                                            FYE within 120 days        Yes  No
     A/R & A/P Agings                                            Monthly within 20 days     Yes  No
     Borrowing Base Certificate                                  Monthly within 20 days     Yes  No

     FINANCIAL COVENANT                                          REQUIRED       ACTUAL      COMPLIES

     Maintain on a monthly basis (unless otherwise noted):
       Minimum Quick Ratio (Adjusted)                            1.80:1.00      ____:1.00   Yes  No
       Quarterly Net Income*                                                                Yes  No
</TABLE>

*    Borrower shall maintain quarterly net income before taxes at least 70% of
     the approved plan by the Borrower's Board of Directors as attached hereto
     as Schedule I (tested quarterly).

<TABLE>
<S>                                               <C>
                                                  ___________________________________
COMMENTS REGARDING EXCEPTIONS:  See Attached.                   BANK USE ONLY

                                                    Received by:____________________
Sincerely,                                                      AUTHORIZED SIGNER

                                                    Date:

Pharsight Corporation                               Verified:_______________________
                                                                AUTHORIZED SIGNER
___________________________________
SIGNATURE                                           Date:___________________________

___________________________________                 Compliance Status:     Yes   No
TITLE                                             ___________________________________
___________________________________
DATE
</TABLE>
<PAGE>

[Logo]
                                SILICON VALLEY BANK


                         PRO FORMA INVOICE FOR LOAN CHARGES



BORROWER:           PHARSIGHT CORPORATION

LOAN OFFICER:       BRYAN JADOT

DATE:               JANUARY 18, 2000


                    REVOLVING LOAN FEE        $9,750.00
                    CREDIT REPORT                 35.00
                    UCC SEARCH FEE               200.00
                    UCC FILING FEE                40.00
                    DOCUMENTATION FEE          1,000.00
                    LEGAL FEE                    250.00

                    TOTAL FEE DUE            $11,275.00
                    -------------            ==========


PLEASE INDICATE THE METHOD OF PAYMENT:

     { }   A CHECK FOR THE TOTAL AMOUNT IS ATTACHED.

     {X}   DEBIT DDA # 3300027682 FOR THE TOTAL AMOUNT.

     { }   LOAN PROCEEDS

BORROWER:

BY: /s/ Robin A. Kehoe
    -----------------------------------
     (AUTHORIZED SIGNER)



/s/ R. Bryan Jadot             1/26/00
---------------------------------------
SILICON VALLEY BANK              (Date)
ACCOUNT OFFICER'S SIGNATURE

<PAGE>

                             NEGATIVE PLEDGE AGREEMENT

     This Negative Pledge Agreement is made as of January 18, 2000 by and
between Pharsight Corporation ("Borrower") and Silicon Valley Bank ("Bank").

In connection with, among other documents, the Loan and Security Agreement (the
"Loan Documents") being concurrently executed herewith between Borrower and
Bank, Borrower agrees as follows:

     1.   Borrower shall not sell, transfer, assign, mortgage, pledge, lease,
          grant a security interest in, or encumber any of Borrower's
          intellectual property, including, without limitation, the following:

          a.   Any and all copyright rights, copyright applications, copyright
               registrations and like protections in each work or authorship and
               derivative work thereof, whether published or unpublished and
               whether or not the same also constitutes a trade secret, now or
               hereafter existing, created, acquired or held;

          b.   All mask works or similar rights available for the protection of
               semiconductor chips, now owned or hereafter acquired;

          c.   Any and all trade secrets, and any and all intellectual property
               rights in computer software and computer software products now or
               hereafter existing, created, acquired or held;

          d.   Any and all design rights which may be available to Borrower now
               or hereafter existing, created, acquired or held;

          e.   All patents, patent applications and like protections including,
               without limitation, improvements, divisions, continuations,
               renewals, reissues, extensions and continuations-in-part of the
               same, including without limitation the patents and patent
               applications;

          f.   Any trademark and servicemark rights, whether registered or not,
               applications to register and registrations of the same and like
               protections, and the entire goodwill of the business of Borrower
               connected with and symbolized by such trademarks, including
               without limitation;

          g.   Any and all claims for damages by way of past, present and future
               infringements of any of the rights included above, with the
               right, but not the obligation, to sue for and collect such
               damages for said use or infringement of the intellectual property
               rights identified above;

          h.   All licenses or other rights to use any of the Copyrights,
               Patents, Trademarks or Mask Works, and all license fees and
               royalties arising from such use to the extent permitted by such
               license or rights; and

          i.   All amendments, extensions, renewals and extensions of any of the
               Copyrights, Trademarks, Patents, or Mask Works; and

          j.   All proceeds and products of the foregoing, including without
               limitation all payments under insurance or any indemnity or
               warranty payable in respect of any of the foregoing;
<PAGE>

     2.   It shall be an event of default under the Loan Documents between
          Borrower and Bank if there is a breach of any term of this Negative
          Pledge Agreement.

     3.   Capitalized terms used but not otherwise defined herein shall have the
          same meaning as in the Loan Documents.

BORROWER:

Pharsight Corporation


By: /s/ Robin A. Kehoe
    ----------------------------

Name: Robin A. Kehoe
      --------------------------

Title: Chief Financial Officer
       -------------------------



BANK:

SILICON VALLEY BANK


By: /s/ R. Bryan Jadot
    ----------------------------

Name: R. Bryan Jadot
      --------------------------

Title:    AVP
       -------------------------

<PAGE>

                           CORPORATE BORROWING RESOLUTION

 BORROWER:    PHARSIGHT CORPORATION           BANK: SILICON VALLEY BANK
              800 W. EL CAMINO REAL                 3003 TASMAN DRIVE
              SUITE 200                             SANTA CLARA, CA 95054-1191
              MOUNTAIN VIEW, CA 94040

I, THE SECRETARY OR ASSISTANT SECRETARY OF PHARSIGHT CORPORATION ("BORROWER"),
CERTIFY that Borrower is a corporation existing under the laws of the State of
California.

I certify that at a meeting of Borrower's Directors (or by other authorized
corporate action) duly held the following resolutions were adopted.

It is resolved that ANY ONE of the following officers of Borrower, whose name,
title and signature is below:


           NAMES                   POSITIONS              ACTUAL SIGNATURES

_________________________  _________________________  __________________________
_________________________  _________________________  __________________________
_________________________  _________________________  __________________________
_________________________  _________________________  __________________________


may act for Borrower and:

     BORROW MONEY.  Borrow money from Silicon Valley Bank ("Bank").

     EXECUTE LOAN DOCUMENTS.  Execute any loan documents Bank requires.

     GRANT SECURITY.  Grant Bank a security interest in any of Borrower's
     assets.

     NEGOTIATE ITEMS.  Negotiate or discount all drafts, trade acceptances,
     promissory notes, or other indebtedness in which Borrower has an interest
     and receive cash or otherwise use the proceeds.

     LETTERS OF CREDIT.  Apply for letters of credit from Bank.

     FOREIGN EXCHANGE CONTRACTS.  Execute spot or forward foreign exchange
     contracts.

     ISSUE WARRANTS.  Issue warrants for Borrower's stock.

     FURTHER ACTS.  Designate other individuals to request advances, pay fees
     and costs and execute other documents or agreements (including documents or
     agreement that waive Borrowers right to a jury trial) they think necessary
     to effectuate these Resolutions.

Further resolved that all acts authorized by these Resolutions and performed
before they were adopted are ratified. These Resolutions remain in effect and
Bank may rely on them until Bank receives written notice of their revocation.

I certify that the persons listed above are Borrower's officers with the titles
and signatures shown following their names and that these resolutions have not
been modified are currently effective.

CERTIFIED TO AND ATTESTED BY:

X ______________________________________________
   *Secretary or Assistant Secretary

X ______________________________________________
*NOTE: In case the Secretary or other certifying officer is designated by the
foregoing resolutions as one of the signing officers, this resolution should
also be signed by a second Officer or Director of Borrower.