Document:

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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]
<PAGE>   5

                                   EXHIBIT B

                                  [FLOOR PLAN]<PAGE>   1
                                                                   EXHIBIT 10.10

                            FIFTH AMENDMENT TO LEASE

     THIS FIFTH AMENDMENT TO LEASE (this "AMENDMENT") is made on this 18th day
of December, 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, a Third Amendment to
Lease dated October 11, 1999, and a Fourth Amendment to Lease dated April 25,
2000, (collectively, the "LEASE"), for Suites 1000, 900, 600, 601, 602, 603, and
604 consisting of approximately 33,599 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 the later of Landlord's substantial
     completion of Landlord's tenant improvement work or January 1, 2001 (the
     "Commencement Date"), the Leased Premises shall consist of approximately
     40,635 rentable square feet, and shall be comprised of the Initial Leased
     Premises and an additional 7,036 rentable square feet known as Suites LL9,
     LL102, 102 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. Upon the Commencement Date, , Tenant shall pay to Landlord
     annual basic rent of Seven Hundred Sixty-Three Thousand Five Hundred Two
     and 20/100 Dollars ($763,502.20), payable in equal monthly installments of
     Sixty-Three Thousand Six Hundred Twenty-Five and 18/100 Dollars
     ($63,625.18). Commencing December 1, 2001, 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. Tenant's Proportionate Share. Upon the Commencement Date, Tenant's
     Proportionate Share as detailed in Sections 1.3 and 1.4 of the Fourth
     Amendment to Lease shall be amended to delete 1.9% and substitute in lieu
     thereof 7.9% Tenant's Proportionate Share is based upon the relationship
     between the square footage of Suites 602, 604, 102, LL9, LL102
     (approximately 9,272 square feet) and the total square footage in the
     Property (approximately 117,334 square feet).

     1.4. Tenant Improvements. Landlord shall provide turn-key tenant
     improvements based upon a space plan mutually agreed upon by Landlord and
     Tenant which shall be known as Exhibit B and attached hereto and made apart
     hereof upon completion of such plan. In addition to building standard
     build-out, Landlord shall:

          o replace all ceiling tiles;

          o provide one (1) dedicated outlet for every four (4) cubicles;

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          o insulate all office and conference room walls;

          o replace glass entry door to suite.

     All finishes shall be Tenant's choice of Landlord's building standard
selections. Landlord shall not be responsible for any of Tenant's low voltage
requirements or other computer cabling requirements.

     1.5. Signage. Tenant shall be entitled to signage, and Tenant's sole cost
     and expense, located above the Leased Premises equal in size, color,
     location, configuration and method of installation to that signage which
     currently exists for current tenant.

     1.6. Parking Spaces. Free of charge to Tenant, the eight (8) parking spaces
     designated on the plat attached hereto as Exhibit B (the "Reserved Spaces")
     shall be reserved for use by Tenant and its customers, guests and invitees.
     Tenant, at Tenant's cost and expense, shall cause an appropriate sign to be
     erected identifying the Reserved Spaces. However, such sign may be erected
     only after Tenant has submitted to Landlord plans for the location and
     appearance of such sign, and Tenant shall have received Landlord's written
     approval thereof. Landlord shall not be obligated in any way to police or
     monitor the use of the Reserved Spaces, nor shall Landlord be required to
     enforce the reservation granted hereunder. Tenant hereby agrees to defend,
     indemnify and hold harmless Landlord from any claim, demand, suit, action,
     expense or cost incurred by or raised against Landlord as a result of the
     reservation granted to Tenant and its customers, guests and invitees
     hereunder.

     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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     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.

     IN WITNESS WHEREOF, Landlord and Tenant have caused this Amendment to be
duly executed under seal on their 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/ [ILLEGIBLE]                          By: /s/ [ILLEGIBLE]             (SEAL)
---------------------------                  ----------------------------

                                         Title: Vice President
                                                -------------------------------

                                         Date: 12/18/00
                                               --------------------------------

WITNESS/ATTEST:                          Tenant:

                                         ADVANCE PARADIGM CLINICAL SERVICES,
                                         INC.

/s/ SCOTT IANNANTUANO                    By: /s/ KEN ZADOORIAN
---------------------------                  ----------------------------------
Scott Iannantuano
                                         Title: SVP Human Resources
                                                -------------------------------

                                         Date: 12-7-00
                                               --------------------------------

                                               [ILLEGIBLE]

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                                   EXHIBIT A

                             [GROUND FLOOR PLAN G]

                                                                 [INITIAL STAMP]
                                     1 OF 2

<PAGE>   5

                                   EXHIBIT A

                              [FIRST FLOOR PLAN 1]

                                                                 [INITIAL STAMP]
                                     2 OF 2
<PAGE>   6
                                   EXHIBIT B

              [Space plan to be attached upon completion of plan.]

<PAGE>   7
                                   EXHIBIT C

                             [PLAN OF PARKING LOT]

                                                                 [INITIAL STAMP]

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