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                                                                    EXHIBIT 10.9


                           FOURTH AMENDMENT TO LEASE


     THIS FOURTH AMENDMENT TO LEASE (this "Amendment") is made as of this 25th
day of April, 2000, by and between HILL MANAGEMENT SERVICES, INC., a Maryland
corporation, agent for the owner ("Landlord"), and ADVANCE PARADIGM CLINICAL
SERVICES, INC., a Maryland corporation ("TENANT").

                                    Recitals
                                    --------

     A.  Whereas, Landlord and Paradigm Pharmacy Management entered into a
Lease dated March 16, 1994, as amended by an Amendment to Lease dated October
19, 1996, a Second Amendment to Lease dated September 30, 1998, and a Third
Amendment to Lease dated October 11, 1999 (collectively, the "LEASE"), for
Suites 1000, 900, 600, 601 and 603 consisting of approximately 31,363 square
feet (the "INITIAL LEASED PREMISES"), which has an address of 11350 McCormick
Road, Hunt Valley, Maryland 21031 and is known as Executive Plaza II (the
"PROPERTY").

     B.  Landlord and Tenant now desire to amend certain provisions of the
Lease.

                                   Agreements
                                   ----------

     NOW, THEREFORE, in consideration of the mutual covenants contained herein,
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, Landlord and Tenant agree as follows:

     Section 1.  Amendment of Lease.  The provisions of the Lease are amended
as follows:

     1.1  Leased Premises.  Commencing July 1, 2000 the Leased Premises shall
consist of approximately 33,599 square feet, and shall be comprised of the
Initial Leased Premises as defined in Section 1.2 of the Third Amendment to
Lease and an additional 2,236 square feet known as Suites 602 and 604 of
Executive Plaza II (the ADDITIONAL LEASED PREMISES"). The Additional Leased
Premises are more particularly depicted as outlined in red on Exhibit A,
attached hereto and made a part hereof.

     1.2  Rent.  Commencing on July 1, 2000, Tenant shall pay to Landlord
annual basic rent of Six Hundred Thirteen Thousand One Hundred Eighty-One and
75/100 Dollars ($613,181.75), payable in equal monthly installments of Fifty One
Thousand Ninety-Eight and 48/100 Dollars ($51,098.48). Commencing December 1,
2000, and for each succeeding lease year thereafter, the annual basic rent
shall be increased to an amount equal to 103% of the annual basic rent for the
immediately preceding lease year as set forth in Section 2.C. of the Lease.

     1.3  Operating Costs.  In the event Operating Costs (hereinafter defined)
for any future calendar year are greater than the Operating Costs for the first
calendar year, such first calendar year to be defined for the purposes of this
paragraph to mean the year 2000, whether during the Initial Lease Term or any
renewal period(s). Tenant shall pay Landlord, as Additional Rent for each such
future calendar year, an amount equal to 1.9% ("TENANT'S PROPORTIONATE SHARE")
of the increase in Operating Costs. Tenant's Proportionate Share is based upon
the relationship between the square footage of the Additional Leased Premises
(approximately 2,236 square feet) and the total square footage in the Property
(approximately 117,334 square feet). As used in this Lease, the term "OPERATING
COSTS" shall mean the aggregate of all reasonable and proper expenses and costs
incurred and paid by Landlord for operating the Property. Such expenses and
costs shall be those that are usual and customary as found in the operation of
other first class office buildings and shall include, but not be limited to,
all expenses and costs that are required to operate, maintain or repair the
building and outside areas of the Property, the cost of capital improvements
designed to protect the health and safety of the tenants in the building, the
cost of all alterations and improvements to the building that are necessary to
comply with the ADA (as hereinafter defined) and the cost of monitoring and
maintaining suitable indoor air quality (including regular inspections and
repairs to the building HVAC system). Such expenses and costs shall not include
as Operating Costs any items for which Landlord will be compensated by
insurance or by reimbursement by a particular tenant of costs directly borne by
others.

     These costs shall also include any costs incurred by Landlord to modify or
retrofit any building system (e.g. HVAC equipment, security devices, elevator
equipment) so that such system(s) will accurately process date and/or time data



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relating to the year 2000; provided that if such costs are deemed to be capital
costs under generally accepted accounting principals, then such costs shall be
amortized over a period of five (5) years.

     1.4.A.  Taxes. Tenant shall pay to Landlord as Additional Rent, Tenant's
Proportionate Share (1.9%) of any increase in real and personal property taxes,
assessments, and other governmental charges (including, but not limited to,
metropolitan charges and frontfoot benefit charges) assessed against the
Property, whether as a result of an increase in assessment or an increase in
tax rate, in excess of the taxes, assessments and charges for the fiscal year
2000-2001. The foregoing shall apply to increases in real estate taxes,
assessments and charges assessed against the Property generally, and not
resulting from improvements placed on the Leased Premises by Tenant. In the
event of any increase resulting from such improvements, Tenant shall pay all of
said increase. Tenant's improvements are considered to be all improvements to
the Leased Premises, except for the shell building, which includes space
heaters, lighting provided by Landlord, and powder rooms, whether the taxes are
payable to the State of Maryland and/or other governing municipalities. Said
taxes, assessments and charges include, but are not limited to, paying taxes
and any and all benefits or assessments which may be levied on the Property
hereby leased, but not including the Income tax or any state or other tax upon
the income or rent payable hereunder. In the event Landlord incurs expenses as
a result of engaging in efforts to reduce the assessment or taxes, Tenant shall
pay Tenant's Proportionate Share of said expenses.

     B.  Other Taxes. Tenant shall assume and pay to Landlord, as Additional
Rent, prior to the imposition of any fine, penalty, interest or costs for the
nonpayment thereof, all excise, sales, gross receipt or other tax (other than a
net income or excess profits tax) which may be (a) assessed or imposed on or be
measured by such rent or other charge which may be treated as rent, (b) which
may be imposed on the letting or other transaction for which such tax is
payable and which Landlord may be required to pay or collect under any law now
in effect or hereafter enacted by any governmental authority, or (c) which may
be imposed by virtue of Tenant's operations in the Leased Premises.

     1.5.  Option to Terminate. Commencing July 1, 2000 Tenant's Option to
Terminate as detailed in Section 1.6 of the Third Amendment to Lease dated
October 11, 1999 shall be of no further force or effect.

     1.6.  Tenant Improvements. Landlord, at its sole cost and expense, shall
provide turn-key Tenant improvements in accordance with the attached floor plan
known as Exhibit B attached hereto and made a part hereof.

     1.7.  Contingency. This amendment shall be expressly contingent upon
Landlord's execution of a relocation amendment with the tenants currently
occupying the Additional Leased Premises.

     Section 2.  Titles of Sections. The section titles used in this Amendment
are for convenience of reference only, and shall not constitute a part of this
Amendment nor shall they affect the meaning, construction or effect of this
Amendment or the Lease.

     Section 3.  Definitions. Unless otherwise set forth in this Amendment, all
capitalized terms shall have the same meaning ascribed to them in the Lease.

     Section 4.  Interpretation. All other terms, covenants and conditions of
the Lease shall remain unchanged and continue in full force and effect except
as such terms, covenants and conditions have been amended or modified by this
Amendment, and this Amendment shall, by this reference, constitute a part of
the Lease.

     Section 5.  Representations. Tenant hereby represents and warrants to
Landlord that, as of the date hereof, it (i) is the sole legal and beneficial
owner of all of the right, title and interest granted to it by the provisions of
the Lease, (ii) has not sold, transferred or encumbered any or all of such
right, title or interest, and (iii) has the full and sufficient right at law and
in equity to execute and deliver this Amendment as the owner of such right,
title, and interest, without the necessity of having any other person's consent
thereto or joinder therein.

     Section 6.  Successors and Assigns. This Amendment and the terms,
covenants and conditions herein contained shall inure to the benefit of and be
binding upon Landlord and its successors and assigns, and Tenant and its
permitted successors and assigns.

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        IN WITNESS WHEREOF, Landlord and Tenant have caused this Amendment to be
duly executed under seal on behalf by their duly authorized representative, as
of the date first above written.


WITNESS/ATTEST:                         Landlord:

                                        HILL MANAGEMENT SERVICES, INC.
                                        agent for the owner

/s/ DANIELLE M. BEYRODT                 By: /s/ [Signature Illegible]  (SEAL)
---------------------------                ----------------------------
                                        Title: VP

                                        Date: 4/25/00


WITNESS/ATTEST:                         Tenant:

                                        ADVANCE PARADIGM CLINICAL SERVICES, INC.

/s/ SUSAN JENKINS                       By: /s/ JOE FILIPEK              (SEAL)
---------------------------                ------------------------------

                                        Printed Name: Joe Filipek

                                        Title: President & CEO

                                        Date: 4/12/00





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                                   EXHIBIT A



                                  [FLOOR PLAN]
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                                   EXHIBIT B


                                  [FLOOR PLAN]