Document:

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                                                                    EXHIBIT 4.10

                             ADVANCE PARADIGM, INC.

                                WARRANT AGREEMENT

         This Warrant Agreement (this "Agreement") dated as of December 10,
1999, entered into by and between Advance Paradigm, Inc., a Delaware corporation
(the "Company") and CareFirst of Maryland, Inc., Group Hospitalization and
Medical Services, Inc., FreeState Health Plan, Inc., Delmarva Health Plan, Inc.
and CapitalCare, Inc. (collectively, "Client").

                               TERMS OF AGREEMENT

         NOW THEREFORE, in consideration of the premises and the mutual
covenants herein contained, the Company and Client hereby agree as follows:

         Section 1. PHARMACEUTICAL SERVICE AGREEMENT. Reference is made to that
certain Pharmaceutical Service Agreement effective as of the date hereof,
entered into by and among Company and Client (the "Service Agreement").
Capitalized terms not otherwise defined herein shall have the meanings given to
them in the Service Agreement.

         Section 2. GRANT OF THE RIGHT TO PURCHASE COMMON STOCK. The Company
hereby grants to Client the right, and Client shall be entitled, subject to the
terms and conditions hereinafter set forth to purchase from the Company 168,750
shares of its common stock, par value $0.01 per share (the "Common Stock")
(which number is referred to herein as the "Total Exercise Number") at a per
share exercise price equal to $21.125 (the "Exercise Price"). The right to
purchase such shares shall be evidenced by five (5) warrant certificates each in
the form of Exhibit A hereto (collectively, the "Warrant Certificates" and each
a "Warrant Certificate"). Subject to Section 3 hereof, each Warrant Certificate
shall be delivered to the Client on the Vesting Date (as defined below) thereof.
The Total Exercise Number and Exercise Price of such shares are subject to
adjustment as provided in Section 4 hereof.

         Section 3. EXERCISE OF WARRANT CERTIFICATES. The purchase rights
granted hereunder will be exercisable as to twenty percent (20%) of the Total
Exercise Number as of September 30, 2000, and the right to exercise with respect
to an additional twenty percent (20%) of the Total Exercise Number will accrue
on each September 30th thereafter that the Service Agreement is in effect (each
a "Vesting Date") and will be cumulative; provided that if the Service Agreement
is terminated for any reason, the vesting schedule will terminate at that time
as well and only that portion of the Warrant which had vested prior to the date
of termination will be considered vested and exercisable. Except as otherwise
provided for herein, the term of the Warrant Certificates and the right to
purchase Common Stock as described therein shall commence on the Vesting Date of
such Warrant Certificate and will end on the earlier of (i) the third month
following termination of the Service Agreement or (ii) September 30, 2006 (the
"Exercise Period"). Shares of Common Stock purchased upon exercise of each
Warrant Certificate shall at the time of purchase be paid for in full. To the
extent that the right to purchase shares has accrued hereunder, the Warrant
Certificates may be exercised by written notice to the Company in the form
attached to the Warrant Certificates, which specifies an exercise date (the
"Date of Exercise"), accompanied by

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full payment for the shares by wire transfer or certified or official bank check
or the equivalent thereof acceptable to Company. Upon the initial exercise of a
Warrant Certificate, Client and the Company shall execute and enter into the
Stockholders Agreement attached hereto as Exhibit B (the "Stockholders
Agreement").

         At the time of delivery, the Company shall, without stock transfer tax
to the holder of the Warrant Certificate ("Holder"), deliver to the Holder (or
to such other person as the Holder directs) at the principal office of the
Company, or such other place as shall be mutually agreed upon, a certificate or
certificates for such shares, provided, however, that the time of delivery may
be postponed by the Company for such period as may be required for it with
reasonable diligence to comply with any requirements of law. The Company at the
time of exercise will require in addition that the registered owner of the
shares deliver an executed copy of the Stockholder Agreement, an investment
representation in form acceptable to the Company, and the Company will place a
legend on the certificate for such Common Stock restricting the transfer of
same. At no time shall the Company have any obligation or duty to register under
the Securities Act of 1933 (the "1933 Act") the Common Stock issuable upon
exercise of a Warrant Certificate.

         Section 4. ADJUSTMENTS TO EXERCISE PRICE AND NUMBER OF SHARES. The
Exercise Price and number of shares of Common Stock purchasable pursuant to the
exercise of the Warrant Certificates shall be subject to adjustment from time to
time as follows:

         (a) Adjustment for Combinations or Consolidations of Common Stock. In
the event the Company, at any time or from time to time after the date hereof;
effects a subdivision or capital reorganization of its outstanding Common Stock
for a greater or lesser number of shares, then and in each such event the Total
Exercise Number and the Exercise Price shall be adjusted proportionately such
that Client is entitled to purchase the same percentage of all shares of the
Company's, outstanding capital stock then issued and issuable for the same
aggregate considerations such Holder was entitled to purchase immediately prior
to such event.

         (b) Adjustment for Certain Dividends and Distributions. In the event
the Company at any time or from time to time after the date hereof shall pay a
dividend payable in Common Stock of the Company, or otherwise make a
distribution of Common Stock to its stockholders, then the Exercise Price shall
be adjusted, from and after the record date of such dividend or the date of such
distribution, to that price determined by multiplying the Exercise Price by a
fraction,

                  (i) the numerator of which shall be the total number of shares
                  of capital stock issued and outstanding or deemed to be issued
                  and outstanding immediately prior to the time of such issuance
                  or the close of business on such record date; and

                  (ii) the denominator of which shall be the number of shares of
                  capital stock issued and outstanding or deemed to be issued
                  and outstanding immediately prior to the time of such issuance
                  or the close of business on such record date plus the number
                  of shares of capital stock to be issued;

         provided, however, that if such record date shall have been fixed and
such dividend is not fully paid or if such distribution is not fully made on
the date fixed therefor, the Exercise Price shall be recomputed accordingly as
of the close of business on such record date and thereafter the

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Exercise Price shall be adjusted pursuant to this Section 4(b) as of the time of
actual payment of such dividend or distribution. Client shall thereafter be
entitled to purchase, at the Exercise Price resulting from such adjustment, the
number of shares of Common Stock (calculated to the nearest whole share)
obtained by multiplying the Exercise Price in effect immediately prior to such
adjustment by the number of shares of Common Stock issuable upon the exercise
hereof immediately prior to such adjustment and dividing the product thereof by
the Exercise Price resulting from such adjustment.

         (c) Number of Shares. Upon any adjustment of the Exercise Price
pursuant to Section 4(b) hereof, Client shall thereafter (until another such
adjustment) be entitled to purchase, at the new Exercise Price, the number of
shares, calculated to the nearest full share, obtained by multiplying the
Exercise Price in effect immediately prior to such adjustment by the number of
shares purchasable pursuant hereto immediately prior to such adjustment and
dividing the product thereof by the new Exercise Price resulting from such
adjustment.

         Section 5. RESERVATION AND AUTHORIZATION OF COMMON STOCK. The Company
shall at all times reserve and keep available, free from preemptive rights, out
of its authorized but unissued Common Stock, solely for the purposes of
effecting the exercise of all outstanding Warrant Certificates, the full number
of shares of Common Stock issuable upon the exercise of all outstanding Warrant
Certificates. For the purpose of this Section 5, the full number of shares of
Common Stock issuable upon the exercise of all outstanding Warrant Certificates
shall be computed as if at the time of computation of such number of shares of
Common Stock all outstanding Warrant Certificates were held by a single holder.
The Company shall from time to time, in accordance with applicable law, increase
the authorized amount of its Common Stock if at any time the authorized amount
of its Common Stock remaining unissued shall not be sufficient to permit the
exercise of all Warrant Certificates at the time outstanding.

         Section 6. TRANSFERABILITY.

         (a) The Warrant Certificates are not transferable by Client except to
the Company or affiliates of Client. Any permitted transfer of a Warrant
Certificate shall be recorded on the books of the Company upon receipt by the
Company of a notice of transfer in the form attached hereto as Exhibit B, at its
principal offices and the payment to the Company of all transfer taxes and
other governmental charges imposed on such transfer. The shares of Common Stock
purchased by Client are not transferable except as provided in the Stockholders
Agreement.

         (b) Unless and until otherwise permitted by this Section and the
Stockholders Agreement, each certificate representing Common Stock initially
issued upon the exercise of each Warrant Certificate (a "Stock Certificate"),
and each certificate for Common Stock issued to any subsequent transferee of any
such certificate, shall be stamped or otherwise imprinted with a legend in
substantially the following form:

                  "THE SECURITIES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN
                  REGISTERED UNDER THE SECURITIES ACT OF 1933 AND MAY BE
                  REOFFERED AND SOLD ONLY IF SO REGISTERED OR IF AN EXEMPTION
                  FROM SUCH REGISTRATION IS AVAILABLE. THE SECURITIES
                  REPRESENTED BY THIS CERTIFICATE ARE ALSO

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                  SUBJECT TO ADDITIONAL RESTRICTIONS ON TRANSFER, CERTAIN
                  REPURCHASE OPTIONS AND CERTAIN OTHER AGREEMENTS SET FORTH IN A
                  STOCKHOLDERS AGREEMENT AMONG THE COMPANY, CAREFIRST OF
                  MARYLAND, INC., GROUP HOSPITALIZATION AND MEDICAL SERVICES,
                  INC., FREESTATE HEALTH PLAN, INC., DELMARVA HEALTH PLAN, INC.
                  AND CAPITALCARE, INC. DATED AS OF __________, A COPY OF WHICH
                  MAY BE OBTAINED BY THE HOLDER HEREOF AT THE COMPANY'S
                  PRINCIPAL PLACE OF BUSINESS WITHOUT CHARGE."

                  Prior to any permitted transfer of a Warrant Certificate or
any Stock Certificate, the holder thereof shall furnish, at the expense of such
holder, to the Company an opinion of counsel, reasonably satisfactory in form
and substance to the Company, to the effect that such transfer is exempt from
registration under the Securities Act. Upon any exercise of any Warrant
Certificate for shares of Common Stock to be registered in the name of a person
other than Client, Client shall furnish, at the expense of Client, to the
Company an opinion of the General Counsel of Client, reasonably satisfactory in
form and substance to the Company, to the effect that the issuance of the shares
of Common Stock to such other person upon exercise of the Warrant is exempt from
registration under the Securities Act.

         Section 7. FRACTIONAL SHARES. The Company shall not be required to
issue a fractional share of stock upon any exercise of a Warrant Certificate. As
to any final fraction of a share that Client would otherwise be entitled to
purchase upon exercise of a Warrant Certificate, the Company shall, if it does
not issue a fractional share, pay a cash adjustment in respect of such final
fraction in an amount equal to the same fraction of the Exercise Price per share
of Common Stock.

         Section 8. EXCHANGE AND REPLACEMENT OF WARRANT CERTIFICATES. In the
event of loss, theft or destruction of a Warrant Certificate, the Company will
make and deliver a new Warrant Certificate of like tenor, in lieu of such
Warrant Certificate, upon receipt by the Company of evidence reasonably
satisfactory to it of such loss, theft, or destruction and indemnity or security
reasonably satisfactory to it, and reimbursement to the Company of all
reasonable expense incidental thereto. In the case of mutilation of a Warrant
Certificate and upon surrender and cancellation of such Warrant Certificate, the
Company will make and deliver a new Warrant Certificate of like tenor, in lieu
of such Warrant Certificate.

         Section 9. RIGHTS PRIOR TO EXERCISE OF WARRANT CERTIFICATES. Prior to
the exercise of a Warrant Certificate, Client shall not be entitled to any
rights of a stockholder of the Company with respect to the Common Stock for
which such Warrant Certificate may then be exercisable, including without
limitation the right to vote, to receive dividends or other distributions or to
exercise any preemptive rights and shall not be entitled to receive any notice
of any proceedings of the Company except as provided herein.

         Section 10. AUTHORIZATION AND ISSUANCE. The Company represents and
warrants to Client that it has the corporate power and authority to issue the
Warrant Certificates; this Warrant Agreement has been duly authorized, executed
and delivered and the Warrant Certificates, when delivered, will be duly and
validly issued, fully paid and nonassessable; the

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issuance of the Warrant Certificates, and the shares of Common Stock issuable
upon their exercise, are not prohibited or restricted by the Certificate of
Incorporation or Bylaws of the Company or any material agreement to which the
Company is a party; except for those agreements for which the Company has
received the requisite consents or waivers; and the shares of Common Stock
issuable upon exercise of the Warrant Certificates, when issued upon exercise of
the Warrant Certificates pursuant to the terms hereof, will be duly and validly
issued, fully paid and nonassessable.

         Section 11. REPRESENTATIONS AND COVENANTS OF CLIENT. This Warrant
Agreement has been entered into by the Company in reliance upon the following
representations and covenants of Client:

         (a) Investment Purpose. The right to acquire the Common Stock issuable
upon exercise of Client's rights contained herein will be acquired for
investment and not with a view to the sale or distribution of any part thereof;
and Client has no present intention of selling or engaging in any public
distribution of the same except pursuant to a registration or exemption.

         (b) Private Issue. Client understands (i) that the Common Stock
issuable upon exercise of the Warrant Certificates is not registered under the
1933 Act or qualified under applicable state securities laws on the ground that
the issuance contemplated by this Warrant Agreement will be exempt from the
registration and qualifications requirements thereof; and (ii) that the
Company's reliance on such exemption is predicated on the representations set
forth in this Section 11.

         (c) Financial Risk. Client has such knowledge and experience in
financial and business matters as to be capable of evaluating the merits and
risks of its investment, and has the ability to bear the economic risks of its
investment.

         (d) Risk of No Registration. Client understands that if the Company
does not register with the Securities and Exchange Commission pursuant to
Section 11 of the 1933 Act, or file reports pursuant to Section 15(d) of the
Securities Exchange Act of 1934 (the "1934 Act"), or if a registration statement
covering the securities under the 1933 Act is not in effect when it desires to
sell the Common Stock issuable upon exercise of the right to purchase, it may be
required to hold such securities for an indefinite period. Client also
understands that any sale of its rights to purchase Common Stock which might be
made by it in reliance upon Rule 144 under the 1933 Act may be made only in
accordance with the terms and conditions of that Rule.

         (e) Stockholders Agreement. Prior to the exercise of any Warrant
Certificate, Client agrees to, and to cause any permitted transferee to, enter
into, execute and perform the Stockholders Agreement.

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Section 12.  GENERAL.

         (a) Expenses. Each party shall bear and pay all costs and expenses
incurred by them respecting the transactions contemplated herein and all
investigations and proceedings in connection therewith, including, without
limitation, fees, commissions or expenses of their respective counsel,
accountants and financial advisors.

         (b) Notice. Any notice required to be given pursuant to the terms and
provisions of this Agreement shall be in writing and shall be sent by certified
mail, return receipt requested, or by overnight delivery service, or facsimile
transmission confirmed by telephone and followed by overnight delivery to the
parties at the addresses below or such other address as shall be specified by
the parties by like notice

                               to the Company at:

                             Advance Paradigm, Inc.
                              Attn: General Counsel
                    545 E. John Carpenter Freeway, Suite 1570
                               Irving, Texas 75062
                              Fax No.: 972/830-6196

                                and to Client at:

                           CareFirst of Maryland, Inc.
                              Attn: General Counsel
                         100 S. Charles Street, Tower II
                               Baltimore, MD 21201

                  Notice so given shall, in the case of notice so given by mail,
be deemed to be given and received on the fourth calendar day after posting, in
the case of notice so given by express delivery service, on the date of actual
delivery and, in the case of notice so given by facsimile transmission or
personal delivery, on the date of actual transmission or personal delivery, as
the case may be.

         (c) Binding Nature and Assignment. This Agreement shall be binding upon
and inure to the benefit of the parties hereto and their successors and assigns.
Neither party may assign this Agreement without the prior written consent of the
other; provided, however, that either party may transfer or assign its rights
and obligations under this Agreement, to any affiliate, and provided further
that no such assignment shall have the effect of releasing such party from any
of its obligations under this Agreement.

         (d) Headings and Interpretation. The headings of the various sections
of this Agreement are inserted for convenience only and do not, expressly or by
implication, limit, define or extend the specific terms of the section so
designated.

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         (e) Governing Law. The validity, enforceability, and interpretation of
this Agreement shall be determined and governed by the internal laws of the
State of Texas (and not the law of conflicts).

         (f) Entire Agreement. This Agreement contains all the terms and
conditions agreed upon by the parties, and supersedes all prior understandings,
writings, proposals, representations, or communications, oral or written, of the
parties hereto.

         (g) Authority. Company and Client warrant that each has full power and
authority to enter into and perform this Agreement, and the person signing this
Agreement on behalf of each party certifies that such person has been properly
authorized and empowered to enter into this Agreement on behalf of such party.

         (h) Non-Waiver. The failure of either party to insist, in any one or
more instances, upon performance of any of the terms, covenants or conditions of
this Agreement shall not be construed as a waiver or a relinquishment of any
right or claim granted or arising hereunder or of the future performance of any
such term, covenant, or condition, and such failure shall in no way affect the
validity of this Agreement or the rights and obligations of the parties
hereunder.

         (i) Survival. Should any part, term or condition of this Agreement be
declared illegal or unenforceable or in conflict with any other laws, the
remaining provisions shall be valid and not affected thereby.

         (j) Counterparts. This Agreement may be executed in any number of
counterparts, each of which shall be deemed an original and all of which taken
together shall constitute one and the same instrument.

         (k) Further Assurances. From time to time upon request and without
further consideration, the parties hereto shall, and shall cause their
subsidiaries and affiliates, to execute, deliver or acknowledge such documents
and do such further acts as the other party hereto may reasonably require to
effectuate its obligations contemplated by this Agreement.

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         IN WITNESS WHEREOF, the parties have caused this Agreement to be
executed and delivered by their proper and duly authorized officers on the date
first above written. By executing the Agreement, the undersigned individuals
hereby warrant and represent that they have read this Agreement in its entirety
and agree to all its terms.

                                       ADVANCE PARADIGM, INC.

                                       By: /s/ DAVID D. HALBERT
                                           -------------------------------------
                                       David D. Halbert
                                       Chairman of the Board and Chief Executive
                                       Officer

                                       CAREFIRST OF MARYLAND, INC.

                                       By: /s/ DAVID D. WOLF
                                           -------------------------------------
                                       Name: David D. Wolf
                                             -----------------------------------
                                       Title: EVP
                                              ----------------------------------

                                       GROUP HOSPITALIZATION AND
                                       MEDICAL SERVICES, INC.

                                       By: /s/ DAVID D. WOLF
                                           -------------------------------------
                                       Name: David D. Wolf
                                             -----------------------------------
                                       Title: Chairman
                                              ----------------------------------

                                       FREESTATE HEALTH PLAN, INC.

                                       By: /s/ DAVID D. WOLF
                                           -------------------------------------
                                       Name: David D. Wolf
                                             -----------------------------------
                                       Title: Chairman
                                              ----------------------------------

                                       DELMARVA HEALTH PLAN, INC.

                                       By: /s/ DAVID D. WOLF
                                           -------------------------------------
                                       Name: David D. Wolf
                                             -----------------------------------
                                       Title:
                                              ----------------------------------

                                       CAPITALCARE, INC.

                                       By: /s/ DAVID D. WOLF
                                           -------------------------------------
                                       Name: David D. Wolf
                                             -----------------------------------
                                       Title:
                                              ----------------------------------

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                                    EXHIBITS

                  Exhibit A     Warrant Certificate

                  Exhibit B     Stockholders Agreement

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                                    EXHIBIT A

THIS WARRANT CERTIFICATE AND THE UNDERLYING SHARES HEREOF HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933 AND MAY NOT BE SOLD OR TRANSFERRED
UNLESS THERE IS AN EFFECTIVE REGISTRATION STATEMENT UNDER SUCH ACT COVERING SUCH
SECURITIES OR THE COMPANY RECEIVES AN OPINION OF COUNSEL (WHICH MAY BE COUNSEL
FOR THE COMPANY) STATING THAT SUCH SALE OR TRANSFER IS EXEMPT FROM THE
REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF SUCH ACT.

                           WARRANT CERTIFICATE NO.
                                                   ---

                     For Purchase of Shares of Common Stock
                                       of
                             ADVANCE PARADIGM, INC.

                                            , 2000
                               -------------

         THIS CERTIFIES THAT CareFirst of Maryland, Inc., Group Hospitalization
and Medical Services, Inc., FreeState Health Plan, Inc., Delmarva Health Plan,
Inc. and CapitalCare, Inc. (collectively, "Client"), or registered transferees
or assigns, is entitled, subject to the terms and conditions set forth in this
Warrant Certificate, to purchase from Advance Paradigm, Inc., a Delaware
corporation (the "Company"), 33,750 (the "Exercise Number") fully paid and
nonassessable shares of Common Stock $0.01 par value per share, of the Company
(the "Common Stock"), at any time during the Exercise Period upon payment in
full of the Exercise Price. The Total Exercise Number and Exercise Price shall
be subject to adjustment as set forth in the Warrant Agreement referred to
below. This Warrant Certificate is issued pursuant to a Warrant Agreement
between Client and the Company dated as of December 10, 1999 (the "Warrant
Agreement"), and is subject to all the terms thereof, including the limitations
on transferability set forth therein. Capitalized terms used herein as defined
terms but not otherwise defined shall have the meaning assigned to such term in
the Warrant Agreement.

         This Warrant Certificate may be exercised, by the holder hereof, for
all shares of Common Stock covered hereby or for a portion of the shares covered
hereby, by the presentation and surrender of this Warrant Certificate together
with the duly executed Election to Purchase in the form attached as hereto, at
the principal office of the Company (or at such other address as the Company may
designate by notice in writing to the holder hereof at the address of such
holder appearing on the books of the Company), and upon payment to the Company
of the Exercise Price and execution of the Stockholders Agreement as set forth
in the Warrant Agreement.

         IN WITNESS WHEREOF, the Company has caused this Warrant Certificate to
be duly executed and delivered by its duly authorized officer as an instrument
under seal as of the date of first above written.

                                                ADVANCE PARADIGM, INC.

                                                By:
                                                    ----------------------------
                                                    David D. Halbert
                                                    Chairman of the Board and
                                                    Chief Executive Officer

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                              ELECTION TO PURCHASE

TO: ADVANCE PARADIGM, INC. (the "Company")

         The undersigned, owner of the accompanying Warrant Certificate hereby
irrevocably exercises the option to purchase ____ shares of Common Stock in
accordance with the terms of such Warrant Certificate, directs that the shares
issuable and deliverable upon such purchase (together with any check for a
fractional interest) be issued in the name of and delivered to the undersigned,
and makes payment in full therefor at the Exercise Price provided or referenced
in such Warrant Certificate.

COMPLETE FOR REGISTRATION OF SHARES OF COMMON STOCK ON THE STOCK TRANSFER
RECORDS MAINTAINED BY THE COMPANY:

--------------------------------------------------------------------------------
Name of Warrant Certificate Holder

--------------------------------------------------------------------------------
Address

--------------------------------------------------------------------------------
Federal ID Tax Number or Social Security Number

--------------------------------------------------------------------------------
Date of Exercise (must be at least fifteen days after the date of this Notice)

                                                --------------------------------
                                                Signature

                                                --------------------------------
                                                Title

                                                --------------------------------
                                                Date

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                                    EXHIBIT B
                              STOCKHOLDER AGREEMENT

         This Stockholder Agreement dated as of ________, by and among CareFirst
of Maryland, Inc., Group Hospitalization and Medical Services, Inc., FreeState
Health Plan, Inc., Delmarva Health Plan, Inc. and CapitalCare, Inc.
(collectively, the "STOCKHOLDER"), and Advance Paradigm, Inc., a Delaware
corporation (the "COMPANY").

                             PRELIMINARY STATEMENTS

                  Pursuant to the terms and conditions of the Warrant Agreement,
dated as of December 10, 1999, by and between the Company and Stockholder, the
Company agreed to issue a warrant to acquire shares of the Company's common
stock, par value $.0l per share (the "COMMON STOCK"). Pursuant to the terms of
the Warrant Agreement, the Stockholder agreed to execute and enter into this
Agreement prior to the issuance of any shares of Common Stock thereunder.

         NOW THEREFORE, in consideration of the premises and the mutual
agreements contained herein and for other good, valuable and binding
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto, intending to be legally bound, hereby agree as follows:

                             STATEMENT OF AGREEMENT

1. Restricted Stock. The terms and conditions of this Agreement shall apply to
all shares of Common Stock issued to Stockholder pursuant to the Warrant
Agreement and any shares of Common Stock otherwise acquired by Stockholder
(collectively the "STOCK").

2. Restrictions on Transfers.

         2.1 Transfers to Affiliate.

         (a) Transfers to Affiliates. Stockholder shall be entitled to transfer
the Stock held by it to entities that directly or indirectly control, are
controlled by, or are under common control with Stockholder (each, an
"AFFILIATE"), provided that any such Affiliates first deliver to the Company
their written acknowledgment of; and agreement to be bound by, the terms and
provisions contained in this Agreement; and the Stockholder delivers to the
Company an opinion of counsel, reasonably acceptable in form and substance to
the Company and its counsel, that registration under the Securities Act is not
required in connection with such transfer. The foregoing notwithstanding,
Stockholder shall not, without the prior written consent of the Company which
consent will not be unreasonably withheld, transfer any shares of Stock to any
Affiliate, nor any officer, director, employee or holder of debt or equity in
any Affiliate that is primarily engaged in the business of pharmacy benefit
management services, pharmacy network management, pharmacy claims adjudication,
mail service pharmacy, pharmacy clinical services,

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and/or pharmacy outcomes management, or the manufacture of drugs, biotech
products or biologicals.

         (b) Affiliates' Proxy. In the event that Stockholder transfers less
than all of its Stock pursuant to Section 2.1(a), Stockholder shall exercise all
of the rights inuring under this Agreement with respect to such transferred
Stock and the transferees shall grant Stockholder proxies to exercise such
rights. In the event that Stockholder transfers all of its Stock pursuant to
Section 2.1(a), one such transferee reasonably acceptable to the Company shall
be designated by Stockholder to exercise all rights inuring under this Agreement
with respect to such Stock and the other transferees shall grant such designated
transferee proxies to exercise such rights.

         2.2 Restrictions on Third Party Transfers of the Stock.

         (a) General. During the first two years following the date the Stock is
issued the ("ISSUANCE DATE"), Stockholder agrees that it will not sell, pledge
or otherwise transfer any interest in any shares of the Stock in a private sale
without the prior written consent of the Company. At any time after the second
anniversary of the Issuance Date, the Stockholder may sell, pledge or otherwise
transfer shares of the Stock to any third party. ("THIRD PARTY TRANSFER");
provided that such transfer is in accordance with this Section 2.2, and provided
further that the transferring Stockholder delivers to the Company an opinion of
counsel, reasonably acceptable in form and substance to the Company and its
counsel, that registration under the Securities Act is not required in
connection with such transfer. The foregoing notwithstanding, Stockholder agrees
to exercise reasonable business prudence in the sale of the Stock and to consult
with the Company regarding the timing of the sale of the Stock. In addition,
Stockholder agrees that it shall not transfer any shares of Stock to any person
or entity, nor any officer, director, employee or holder of debt or equity in
any entity that is engaged in the business, or has an affiliate engaged in the
business of pharmacy benefit management services, pharmacy network management,
pharmacy claims adjudication, mail service pharmacy, pharmacy clinical
services, and/or pharmacy outcomes management, or the manufacture of drugs,
biotech products or biologicals.

         (b) Sale Notice. At least 30 days prior to making any Third Party
Transfer under Section 2.2(a), the transferring Stockholder will deliver a
written notice (the "SALE NOTICE") to the Company. The Sale Notice will disclose
in reasonable detail the identity of the prospective transferee(s) and the terms
and conditions of the proposed transfer. Stockholder agrees not to consummate
any such transfer until 30 days after the Sale Notice has been delivered to the
Company.

         (c) First Refusal Rights. The Company may elect to purchase all of the
Stock to be transferred upon the same terms and conditions as those set forth in
the Sale Notice by delivering a written notice of such election to Stockholder
within 15 days after the receipt of the Sale Notice by the Company. If the
Company elects to purchase any shares of Stock, the Company shall consummate
such purchase within 30 days of delivery of notice of intent to purchase. If the
Company has not elected to purchase all of the Stock specified in the Sale
Notice, Stockholder may transfer the Stock specified in the Sale Notice at a
price and on terms no more favorable to the transferee(s) thereof than specified
in the Sale Notice during the 60-day period immediately following notice of the
Company's election not to purchase such shares. Any shares of Stock not

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transferred within such 60-day period will be subject to the provisions of this
Section 2.2(c) upon subsequent transfer.

         (d) Non-Cash Consideration. In the event the consideration for the
Stock as disclosed in the Sale Notice is other than cash, a promissory note or a
combination thereof; the price for the Stock shall be the value of that
consideration as agreed to by the transferring Stockholder and the Company, or,
if no agreement can be reached as to the valuation of such consideration, the
fair market value of such consideration as determined by two appraisers (one
appointed by the Stockholder and one appointed by the Company). In the event the
two appraisers are unable to agree on a fair market value within 20 days after
they are appointed, the fair market value of the consideration shall be the
average of the appraised values of the two appraisers; provided, however, that
if the appraised values of the two appraisers differ by more than five percent
(5%) of the higher of the two appraised values, the two respective appointed
appraisers shall select a third appraiser who shall independently, within 20
days after this appointment, make a determination of the value of the
consideration and the average of the appraised values of the three appraisers
shall be the purchase price and shall be binding on the parties hereto. The
transferring Stockholder and the Company shall each bear the cost of their
respective appraisers and shall share the cost equally of the third appraiser,
if any. Notwithstanding anything herein to the contrary, if an appraisal is used
to determine the value of the consideration pursuant to this Section 2.2(d), the
time periods provided for in Sections 2.2(b) and 2.2(c) shall be tolled from the
time of the initial appointment of the two appraisers until a final appraised
value is determined pursuant to this Section 2.2(d).

         (e) Public Sale. Notwithstanding the foregoing, the Stockholder may
sell, pledge or otherwise transfer shares of the Stock to the public in a market
transaction in accordance with applicable securities laws without complying
with the restrictions set forth in Section 2.2(a),(b), (c) and (d). The Company
hereby represents and warrants that it will remain current in its Securities
Exchange Act of 1934 filings in order to facilitate the public sale of the
Stock.

         2.3 Legend. The certificates representing the Stock will bear the
following legend:

                  "THE SECURITIES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN
                  REGISTERED UNDER THE SECURITIES ACT OF 1933 AND MAY BE
                  REOFFERED AND SOLD ONLY IF SO REGISTERED OR IF AN EXEMPTION
                  FROM SUCH REGISTRATION IS AVAILABLE. THE SECURITIES
                  REPRESENTED BY THIS CERTIFICATE ARE ALSO SUBJECT TO ADDITIONAL
                  RESTRICTIONS ON TRANSFER, CERTAIN REPURCHASE OPTIONS AND
                  CERTAIN OTHER AGREEMENTS SET FORTH IN A STOCKHOLDER AGREEMENT
                  AMONG THE COMPANY, CAREFIRST OF MARYLAND, INC., GROUP
                  HOSPITALIZATION AND MEDICAL SERVICES, INC., FREESTATE HEALTH
                  PLAN, INC., DELMARVA HEALTH PLAN, INC. AND CAPITALCARE, INC.
                  DATED AS OF _______________, A COPY OF WHICH MAY BE OBTAINED
                  BY THE HOLDER HEREOF AT THE COMPANY'S PRINCIPAL PLACE OF
                  BUSINESS WITHOUT CHARGE."

                                       14
<PAGE>   15

         Prior to any permitted transfer of the Stock, the Stockholder shall
furnish, at its expense, a written opinion of counsel, reasonably satisfactory
in form and substance to the Company, to the effect that such transfer is exempt
from registration. Upon receipt of such opinion, any legend endorsed on a
certificate pursuant to Section 2.3 hereof and the stop transfer instructions
and record notations with respect thereto shall be removed and the Company shall
issue a certificate without such legend to the Stockholder.

         2.4 Extraordinary Transaction. In the event of a merger of the Company
with a third party where the Company is not the surviving entity, sale of a
majority of the capital stock of the Company, or the sale of all or
substantially all of its assets ("EXTRAORDINARY TRANSACTION"), the Stock shall
be entitled to receive the same benefits as the holders of the Common Stock will
receive in the Extraordinary Transaction. Upon the request of the Board of
Directors of the Company, the Stockholder agrees to consent to, vote in favor of
and execute all required documents in connection with the Extraordinary
Transaction.

         2.5 Limitation on Stock Holdings. The Stockholder agrees that in no
event, shall it, either independently or together with its Affiliates, own
Common Stock or rights to acquire Common Stock, that represent, or if converted
to Common Stock would represent, more than ten percent (10%) of the Company's
issued and outstanding Common Stock, without the Company's prior written
consent.

3. Guaranty. Company hereby guarantees that Stockholder will make an average
minimum profit of $400,000 in connection with the sale of the full amount of
Stock issued in connection with each of the Warrant Certificates exercised and
sold by Stockholder. Such average will be calculated at the time all Warrant
Certificates that Stockholder is entitled to pursuant to the terms of this
Agreement have vested and all shares issued thereunder have been sold. This
guaranty shall survive the termination of the Service Agreement (as defined in
the Warrant Agreement) for a period of two (2) years following the date of
termination.

4. Notices.

         All notices and other communications hereunder shall be in writing and
shall be deemed to have been duly given if delivered personally, mailed by
certified mail (return receipt requested) or sent by express delivery service,
or facsimile transmission (confirmed by telephone conversation and followed by
overnight delivery) to the parties at the following addresses or at such other
addresses as shall be specified by the parties by like notice:

                           if to the Company:

                           Advance Paradigm, Inc.
                           Attn: General Counsel
                           545 E. John Carpenter Freeway
                           Suite 1570
                           Irving, TX 75062
                           Fax No.: (972) 830-6196

                           if to Stockholder:

                                       15
<PAGE>   16

                           CareFirst of Maryland, Inc.
                           Attn: General Counsel
                           100 S. Charles Street, Tower II
                           Baltimore, MD 21201

         Notice so given shall, in the case of notice so given by mail, be
deemed to be given and received on the fourth calendar day after posting, in the
case of notice so given by express delivery service, on the date of actual
delivery and, in the case of notice so given by facsimile transmission or
personal delivery, on the date of actual transmission or personal delivery, as
the case may be.

5. Severability.

         If any provision of this Agreement shall be held to be illegal, invalid
or unenforceable under any applicable law, then such contravention or invalidity
shall not invalidate the entire Agreement. Such provision shall be deemed to be
modified to the extent necessary to render it legal, valid and enforceable, and
if no such modification shall render it legal, valid and enforceable, then this
Agreement shall be construed as if not containing the provision held to be
invalid, and the rights and obligations of the parties shall be construed and
enforced accordingly.

6. Complete Agreement.

         This Agreement and those documents expressly referred to herein and of
even date herewith, embody the complete agreement and understanding among the
parties and supersede and preempt any prior understandings, agreements or
representations by or among the parties, written or oral, which may have related
to the subject matter hereof in any way.

7. Counterparts.

         This Agreement may be executed in any number of counterparts and by
different parties hereto in separate counterparts, with the same effect as if
all parties had signed the same document. All such counterparts shall be deemed
an original, shall be construed together and shall constitute one and the same
instrument.

8. Successors and Assigns.

         This Agreement is intended to bind and inure to the benefit of and be
enforceable by and against the Stockholder and the Company, and their respective
heirs, successors and assigns. Stockholder hereby agrees not to transfer or
assign, directly or indirectly, any of the Stock unless such transferee or
assignee agrees in writing (i) to be bound by the provisions of this Agreement
and (ii) not to make subsequent assignments or transfers other than in
accordance with this Agreement. Notwithstanding the foregoing, any holder of the
Stock (other than a holder who purchases the stock through a market sale) shall
be bound by the provisions of this Agreement even if such holder is not a party
hereto or otherwise agreed in writing to be bound by the provisions hereof.

                                       16
<PAGE>   17

9. CHOICE OF LAW.

         THE INTERNAL LAW OF THE STATE OF TEXAS (AND NOT THE LAW OF CONFLICTS)
WILL GOVERN THE CONSTRUCTION, VALIDITY AND INTERPRETATION OF THIS AGREEMENT.

10. Remedies.

         Each of the parties to this Agreement will be entitled to enforce its
rights under this Agreement specifically, to recover damages by reason of any
breach of any provision of this Agreement and to exercise all other rights
existing in its favor. The parties hereto agree and acknowledge that money
damages may not be an adequate remedy for any breach of the provisions of this
Agreement and that any party may in its sole discretion apply to any court of
law or equity of competent jurisdiction for specific performance and/or
injunctive relief in order to enforce or prevent any violations of the
provisions of this Agreement. In the event a party hereto brings an action under
this agreement, the prevailing party in such dispute shall be entitled to
recover from the losing party all fees, costs and expenses of enforcing any
right of such prevailing party under or with respect to this Agreement,
including without limitation such reasonable fees and expenses of attorneys and
accountants, which shall include, without limitation, all fees, costs and
expenses of appeals.

11. Amendments and Waivers.

         Any provision of this Agreement may be amended or waived only with the
prior written consent of each of the parties hereto.

12. Confidentiality.

         Each of the parties hereto agrees to hold in the strictest confidence
the existence of this Agreement and the terms and conditions hereof.
Specifically, but without limiting the generality of the foregoing, each of the
parties hereto agrees not to disclose the existence of this Agreement or any of
its terms to any third party without the prior written consent of every other
party hereto (unless such disclosure is required by law).

                            [Signature page follows]

                                       17<PAGE>   1
                                                                    EXHIBIT 10.6

                               AMENDMENT TO LEASE

     THIS AMENDMENT TO LEASE (this "AMENDMENT") is made as of this 19th day of
October, 1996, 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 (the "LEASE"), for Suite 1000 consisting of approximately
11,609 square feet (the "INITIAL LEASED PREMISES"), which has an address of
11350 McCormick Rd., Hunt Valley, Maryland 21031, and is known as Executive
Plaza II (the "PROPERTY").

     B. WHEREAS, by separate agreement, Paradigm Pharmacy Management
transferred all of its rights, titles and interests in the Lease to Tenant.

     C. WHEREAS, Landlord and Tenant now desire to amend certain provisions of
the Lease to provide Tenant with additional office space in the Property.

                                   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. Term. Commencing October 1, 1996, the term of the Lease shall be
extended for three (3) months and the Expiration Date as set forth in Paragraph
1.A. of the Lease, as amended, shall be August 31, 1999.

     1.2. Leased Premises. Commencing October 1, 1996, the Leased Premises
shall consist of approximately 17,205 square feet, and shall be comprised of
the Initial Leased Premises and an additional 5,596 square feet known as Suite
600 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.

     1.3. Rent. Commencing October 1, 1996, Tenant shall pay to Landlord annual
basic rent of Two Hundred Ninety-Two Thousand Forty-Four and 54/100 Dollars
($292,044.54), payable in equal monthly installments of Twenty-Four Thousand
Three Hundred Thirty-Seven and 04/100 Dollars ($24,337.04). Commencing June 1,
1997, 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.

     1.4. Tenant Improvements. Landlord shall construct the Additional Leased
Premises using Tenant's choice of building standard materials in accordance
with the plan dated September 13, 1996 prepared by Rubeling & Associates
attached hereto and made a part hereof as Exhibit B. In addition, Landlord
shall install its choice of new carpeting and new wallcovering in the sixth
floor lobby of the Property. Said lobby's finishes shall be similar in
appearance to the lobby finishes currently existing on the fifth floor of the
Property. Tenant's selections of building standard materials is attached hereto
and made a part hereof as Exhibit C.

     1.5. Requirement to Lease Additional Space. On March 1, 1997, Tenant shall
be required to begin leasing an additional 1,055 square feet of space in the
Property, known as Suite 601 (the "Required Expansion Space"). On or before
February 1, 1996, Landlord and Tenant shall enter into an appropriate amendment
to this Lease subjecting the Required Expansion Space to the terms, covenants,
and conditions contained in this Lease, except that (i) the annual basic rental
for the Required Expansion Space will be the same as the then-current (on a
per-square-foot basis) annual basic rental for the Leased Premises and (ii)
Landlord shall provide Tenant with a $7.50 per square foot allowance for
improvements to the Required Expansion Space. If the cost to Landlord of making
the improvements (the "Cost") is less than $7.50 per square foot multiplied by
1,055 square feet ($7,912.50) (the "Product"), then the difference shall be
applied toward monthly base rent as it is owed. If the Cost is greater than the
Product, then Tenant shall remit to Landlord a check made payable to Landlord
for the difference within fifteen (15) days after it occupies the Required
Expansion Space.

     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.

                                       1
<PAGE>   2

         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.

         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/ KRISTYN L. HARVEY                   By: /s/ [ILLEGIBLE]               (SEAL)
-------------------------------            -------------------------------------

                                        Title: VP
                                               ---------------------------------

                                        Date: 10/19/96
                                              ----------------------------------

WITNESS/ATTEST:                         Tenant:

                                        ADVANCE PARADIGM CLINICAL SERVICES, INC.

/s/ DONNA W. ROBBINS                    By: /s/ ROBERT L. CINQUEGRANA     (SEAL)
-------------------------------            -------------------------------------

                                        Printed Name: Robert L. Cinquegrana
                                                      --------------------------

                                        Title: Vice President & Chief Operating
                                               Officer
                                               ---------------------------------

                                        Date: 9/13/96
                                              ----------------------------------

                                       2

<PAGE>   3

                                   EXHIBIT A

                                  [FLOOR PLAN]

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