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                                                                   EXHIBIT 10.12

                                 FIRST AMENDMENT
                                       TO
                              EMPLOYMENT AGREEMENT

         THIS FIRST AMENDMENT TO EMPLOYMENT AGREEMENT (this "Amendment") is made
and entered into as of March 8, 2000 by and between Caremark Rx, Inc., a
Delaware corporation ("Caremark") and Edward L. Hardin, Jr. ("Officer").
Capitalized terms used herein and not otherwise defined herein shall have the
meanings ascribed to them in that certain Employment Agreement by and between
Caremark and Officer dated July 1, 1998 (the "Employment Agreement").

         WHEREAS, Caremark and Officer entered into the Employment Agreement
whereby Officer agreed to serve as Executive Vice President and General Counsel
of Caremark; and

         WHEREAS, Caremark and Officer desire to amend Section 6 of the
Employment Agreement so as to eliminate ambiguity and confirm the parties
original intent with respect to Officer's incentive compensation arrangements.

         NOW, THEREFORE, in consideration of the foregoing recitals and the
mutual covenants and agreements contained in this Amendment, the parties agree
as follows:

         1.       Amendment to Section 6. Section 6 of the Employment Agreement
shall be deleted in its entirety and the following shall be inserted in lieu
thereof:

                  "Section 6.  Incentive Compensation.

                  During the Term, Officer shall be eligible to receive from
                  Employer annual incentive compensation in amount up to one
                  hundred percent (100%) of Officer's base salary (pro-rated for
                  any particular calendar year during the term); provided,
                  however, that for services rendered during calendar year 1998,
                  Officer shall be eligible to receive from Employer incentive
                  compensation in an amount up to $400,000.00, less state and
                  federal tax and other legally required and Officer-authorized
                  withholdings. The incentive compensation contemplated by this
                  Section 6 shall be payable to Officer solely at the discretion
                  of the Chief Executive Officer of Employer based upon
                  Officer's performance. The incentive compensation which
                  Officer shall be eligible to earn under this Section 6 shall
                  be subject to review and adjustment by the Board (or a
                  Committee of the Board) from time-to-time consistent with past
                  practice."

         2.       No other Amendment. Except as otherwise modified by this
Amendment, all other terms and conditions of the Employment Agreement shall not
be modified or amended and shall remain in full force and effect.

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         3.       Miscellaneous.

                  (a) Entire Agreement. This Amendment, together with the
Employment Agreement, contains the entire agreement of the parties relating to
the subject matter hereof and thereof, and it replaces and supersedes any prior
agreements between the parties relating to said subject matter.

                  (b) Waiver and Amendment. No provision of this Amendment may
be waived except by a written agreement signed by the waiving party. The waiver
of any term or condition of this Amendment shall not be deemed to constitute the
waiver of any other term or condition. This Amendment may be amended only by a
written agreement signed by each of the parties hereto.

                  (c) Captions. Captions have been inserted solely for the
convenience of reference and in no way define, limit or describe the scope or
substance of any provisions of this Amendment.

                  (d) Governing Law. This Amendment shall be governed by the
laws of the State of Alabama.

         IN WITNESS WHEREOF, the parties have executed this Amendment as of the
date first above written.

Attest:                                       CAREMARK Rx, INC.

By:  /s/ SARA J. FINLEY                          By: /s/ E. Mac Crawford
   ------------------------------
Name:  SARA J. FINLEY                            E. Mac Crawford
     ----------------------------
Title:  SENIOR VP                                Chairman of the Board
      ---------------------------

                                                 By: /s/ Edward L. Hardin, Jr.
                                                 Edward L. Hardin, Jr.<PAGE>   1
                                                                  EXHIBIT 10.13

                              EMPLOYMENT AGREEMENT

         THIS EMPLOYMENT AGREEMENT (this "Agreement") is made and entered into
as of August 7, 1998 by and between MedPartners, Inc., a Delaware corporation
("Employer"), and Brad Karro ("Officer").

                                    RECITALS

         WHEREAS, Employer desires to retain the services of Officer and
Officer desires to serve Employer in the capacity of Senior Vice President, COO
Southern California; and

         WHEREAS, Employer and Officer desire to set forth the terms and
conditions of Officer's employment with Employer under this Agreement.

                                   AGREEMENT

         NOW, THEREFORE, in consideration of the foregoing recitals and of the
mutual covenants and agreements contained in this Agreement, the parties agree
as follows:

         1.       Term. Employer agrees to employ Officer, and Officer agrees
to serve Employer, on an "at will" basis for such period (such period being the
"Term") as Employer desires to employ Officer and Officer agrees to serve
Employer. Without limiting the generality of the foregoing sentence, Employer
shall have the right to terminate Officer at any time for any reason or no
reason without any obligation to Officer other than for Base Salary (as
hereinafter defined) earned but unpaid through the date of such termination.

         2.       Employment of Officer.

                  (1)      Position; Duties. Employer and Officer agree that,
subject to the provisions of this Agreement Officer will serve as the Senior
Vice President, COO Southern California of Employer.

         3.       Compensation.

                  (1)      Salary. Employer shall pay Officer a salary in the
amount of $275,000 per year (pro-rated for any partial year during the Term)
(the "Base Salary") payable in equal semimonthly installments, less state and
federal tax and other legally required withholdings. The Base Salary shall be
subject to review and adjustment by the Board (or a Committee of the Board)
from time-to-time consistent with past practice.

                  (2)      Incentive Compensation. During the Term, Officer
shall be eligible to receive from Employer incentive compensation in an amount
equal to fifty (50%) percent of Base Salary (pro-rated for any partial calendar
year during the Term), less state and federal tax and other

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legally required and Officer-authorized withholdings. The incentive
compensation contemplated by this Section 3(b) shall be payable to Officer
solely at the discretion of the President and Chief Executive Officer of
Employer based upon Officer's performance hereunder. The incentive compensation
which Officer shall be eligible to earn under this Section 3(b) shall be
subject to review and adjustment by the Board (or a Committee of the Board)
from time-to-time consistent with past practice.

         4.       Benefits.

                  (1)      Stock Options Plans. As a material inducement to
officer executing this Agreement, the Officer shall be granted options to
purchase 150,000 shares of MedPartners, Inc. common stock, $0.001 par value.
The terms of such options to be governed by the MedPartners, Inc. 1998 New
Employee Stock Option Plan and a stock option agreement substantially in the
form of Exhibit A attached hereto.

                  (2)      Fringe Benefits. In addition to the compensation and
other remuneration provided for in this Agreement, Officer shall be entitled,
during the Term, to such other benefits of employment with Employer as are now
or may after the date of this Agreement be in effect for employees of Employer
at the same level as Officer.

                  (3)      Relocation Package. Officer shall be entitled to
receive Employer's standard relocation package as set forth in the MedPartners,
Inc. Relocation Policy and Procedure Statement attached hereto as Exhibit B. In
addition, Officer shall be entitled to receive an amount equal to $91,666.67,
less state and federal tax and other legally required and Officer authorized
withholdings, for certain miscellaneous items associated with Officer's
relocation.

                  (4)      Expenses. During the Term, Employer shall reimburse
Officer promptly for all reasonable travel, entertainment, parking, business
meeting and similar expenditures in pursuit and furtherance of Employer's
business upon receipt of reasonable supporting documentation as required by
Employer's policies applicable to its officers generally.

                  (5)      Termination Benefits. Notwithstanding any provision
of this Agreement to the contrary, if Officer is terminated by Employer for any
reason other than for "cause" (as hereinafter defined), Officer shall be
entitled to receive and Employer shall be obligated to pay, as severance for
such termination, an amount equal to one year's Base Salary, less state and
federal tax and other legally required withholdings. As defined herein, the
term "Cause" shall mean Officer (i) materially breaches any material term of
this Agreement, (ii) is convicted by a court of competent jurisdiction of a
felony, (iii) refuses, fails or neglects to perform his duties under this
Agreement in a manner substantially detrimental to the business of Employer,
(iv) engages in illegal or other wrongful conduct substantially detrimental to
the business or reputation of Employer, or (v) develops or pursues interests
substantially adverse to Employer; provided, however, that in the case of
clauses (i), (iii), (iv), or (v), no such termination shall be effective unless
(1) Employer shall have given Officer 30 days' prior written notice of any
conduct or deficiency in performance by Officer that Employer believes could,
if not discontinued or corrected, lead to Officer's termination under this

                                      -2-
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Section 4(5) in order that Officer shall have had an opportunity to cure such
noncomplying conduct or performance, and (2) Officer shall not have cured such
noncomplying conduct or performance during such notice period.

         5.       Trade Secrets and Confidentiality

                  (1)      Trade Secrets. Officer agrees and covenants that,
both during the Term and after termination of his employment, Officer will hold
in a fiduciary capacity for the benefit of Employer, and shall not directly or
indirectly use or disclose, except as authorized by Employer in connection with
the performance of Officer's duties, any Trade Secret, as defined hereinafter,
that Officer may have or acquire during the Term for so long as the such
information remains a Trade Secret. The term "Trade Secret" as used in this
Agreement shall mean information including, but not limited to, technical or
non-technical data, a formula, a pattern, a compilation, a program, a device, a
method, a technique, a drawing, a process, financial data, financial plans,
product plans, or a list of actual or potential customers or suppliers,
including without limitation, information received by Employer or Officer from
any client or potential client of Employer, which:

                  1.       derives economic value, actual or potential, from
                           not being generally known to, and not being readily
                           ascertainable by proper means by, other persons who
                           can obtain economic value from its disclosure or
                           use; and

                  2.       is the subject of reasonable efforts by Employer or
                           the client from which the information was received
                           to maintain its secrecy.

                  (2)      Confidentiality. In addition to the covenants set
forth in Section 5(a) and not in limitation thereof, Officer agrees that,
during the Term and for a period of five (5) years after termination of his
employment, Officer will hold in a fiduciary capacity for the benefit of
Employer and shall not directly or indirectly use or disclose, except as
authorized by Employer in connection with the performance of Officer's duties,
any Confidential or Proprietary Information, as defined hereinafter, that
Officer may have or acquire (whether or not developed or compiled by Officer
and whether or not Officer has been authorized to have access to such
Confidential or Proprietary Information) during the Term. The term
"Confidential or Proprietary Information" as used in this Agreement means any
secret, confidential or proprietary information of Employer, including
information received by Employer or Officer from any client or potential client
of Employer, not otherwise included in the definition of "Trade Secret" in
Section 5(a) above. The term "Confidential or Proprietary Information" does not
include information that has become generally available to the public by the
act of one who has the right to disclose such information without violating any
right of the client to which such information pertains.

                  (3)      Restrictions Supplemental to State Law. The
restrictions set forth in Sections 5(a) and (b) are in addition to and not in
lieu of protections afforded to trade secrets and confidential information
under applicable state law. Nothing in this Agreement is intended to or shall
be interpreted as diminishing or otherwise limiting Employer's right under
applicable state law to protect its trade secrets and confidential information.

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         6.       Miscellaneous.

                  (1)      Succession. This Agreement shall inure to the
benefit of and shall be binding upon Employer, its successors and assigns, but
Employer shall not have the right to assign this Agreement without the prior
written consent of Officer. The obligations and duties of Officer under this
Agreement shall be personal and not assignable.

                  (2)      Notices. Any notice, request, instruction or other
document to be given under this Agreement by any party to the others shall be
in writing and delivered in person or by courier, telegraphed, telexed or sent
by facsimile transmission or mailed by certified mail, postage prepaid, return
receipt requested (such mailed notice to be effective on the date of such
receipt is acknowledged), as follows:

                           If to Officer:

                                    Brad Karro

                                    --------------------------------

                                    --------------------------------

                           If to Employer:

                                    MedPartners, Inc.
                                    3000 Galleria Tower
                                    Suite 1000
                                    Birmingham, Alabama 35244
                                    Attn: President and Chief Executive Officer

or to such other place as either party may designate as to itself by written
notice to the other.

                  (3)      Waiver; Amendment. No provision of this Agreement
may be waived except by a written agreement signed by the waiving party. The
waiver of any term or of any condition of this Agreement shall not be deemed to
constitute the waiver of any other term or condition. This Agreement may be
amended only by a written agreement signed by the parties.

                  (4)      Governing Law. This Agreement shall be construed
under and governed by the internal laws of the State of Alabama, without regard
to Alabama's choice of law rules.

                  (5)      Arbitration. Any disputes or controversies arising
under this Agreement shall be settled by arbitration in Birmingham, Alabama in
accordance with the rules of the American Arbitration Association relating to
the arbitration of commercial disputes. The determination and findings of such
arbitrators shall be final and binding on all parties and may be enforced, if
necessary, in the courts of the State of Alabama.

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                  (6)      Captions. Captions have been inserted solely for the
convenience of reference and in no way define, limit or describe the scope or
substance of any provisions of this Agreement.

                  (7)      Severability. If this Agreement shall for any reason
be or become unenforceable by any party, this Agreement shall thereupon
terminate and become unenforceable by the other party as well. In all other
respects, if any provision of this Agreement is held invalid or unenforceable,
the remainder of this Agreement shall nevertheless remain in full force and
effect and, if any provision is held invalid or unenforceable with respect to
particular circumstances, it shall nevertheless remain in full force and effect
in all other circumstances.

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         IN WITNESS WHEREOF, the parties have executed this Agreement as of the
date first above written.

                                    MEDPARTNERS, INC.

                                    /s/ E. Mac Crawford
                                    -----------------------------
                                    E. Mac Crawford
                                    President and CEO

                                    /s/ Brad Karro
                                    -----------------------------
                                    Brad Karro

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                                                                       EXHIBIT A

                         Form of Stock Option Agreement

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                                                                       EXHIBIT B

                   Relocation Policy and Procedure Statement

                                      -7-

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