Document:

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                                                                   EXHIBIT 10.15

                             KEY EMPLOYEE AGREEMENT
                             ----------------------

     In consideration of my employment by Merck-Medco Managed Care, L.L.C.,
and/or any of its corporate parents, subsidiaries, divisions or affiliates, or
the successors or assigns of any of the foregoing (hereinafter collectively
referred to as "Employer"), I hereby agree as follows:

1. Property Rights. All data, concepts, ideas, designs, findings, discoveries,
inventions, improvements, advances, methods, formulas, plans, programs (computer
or otherwise), practices, techniques, developments and relationships with
customers and prospective customers relating in any way to the present and/or
contemplated products, services, or business of the Employer (collectively
"Developments") that I may conceive, make, invent or suggest during or as a
result of my employment by the Employer, whether acting alone or in conjunction
with others, shall be the sole and absolute property of the Employer free of any
rights of any kind on my part. I will promptly make full disclosure of all
Developments to the Employer. I agree to do all acts and things (including,
among others, the execution and delivery of patent and copyright applications
and instruments of assignment) deemed by the Employer to be necessary or
desirable at any time in order to effect the full assignment to the Employer of
my rights, if any, to such Developments.

2. Covenant Against Use and Disclosure. I recognize that in connection with my
employment, I may learn of, and/or it may be desirable or necessary for the
Employer to disclose to me confidential information ("Confidential
Information"). I understand that Confidential Information is valuable and
proprietary to the Employer (or to third parties that have entrusted the
Confidential Information to the Employer). I agree that, except as required by
my employment with the Employer, I will not at any time, directly or indirectly,
use, publish, communicate, describe, disseminate, or otherwise disclose
Confidential Information to any person or entity without the express prior
written consent of the Employer. The term Confidential Information shall
include, but shall not be limited to: (a) customer lists, lists of potential
customers and details of agreements with customers; (b) acquisition, expansion,
marketing, financial and other business information and plans of the Employer;
(c) research and development; (d) data concerning usage of prescription drugs
and any other data compiled by the Employer; (e) computer programs; (f) sources
of supply; (g) identity of specialized consultants and contractors and
Confidential Information developed by them for the Employer; (h) purchasing,
operating and other cost data; (i) special customer needs, cost and pricing
data; (j) employee information (including, but not limited to, personnel,
payroll, compensation and benefit data and plans); and (k) patient records and
data, including all such information recorded in manuals, memoranda,
projections, minutes, plans, drawings, designs, formula books, specifications,
computer programs and records, whether or not legended or otherwise identified
by the Employer as Confidential Information, as well as such information that is
the subject of meetings and discussions and not recorded. Confidential
Information shall not include such information that is generally available to
the public (other than as a result of a disclosure by me or others in violation
of law or agreement) or that is disclosed to me by a third party under no
obligation to keep such information confidential.

3. Return of Documents. Upon the termination of my employment with the Employer
or upon the Employer's request, whichever is sooner, I shall immediately deliver
to the Employer all plans, designs, drawings, specifications, listings, manuals,
records, notebooks, computer memory, disks or programs, and similar repositories
of or containing Confidential

<PAGE>

Information or other data relating to the Employer's products, services, or
business then in my possession or control or available from other persons
receiving such documents from me, whether prepared by me or others. I shall not
retain any copies or abstracts of any such documents.

4. Restrictions on Competitive Employment. During my employment, and for a
period of twelve (12) months following the termination of my employment, I will
not (as an individual, principal, agent, employee, consultant, or otherwise),
directly or indirectly in any territory in which the Employer and/or any of its
affiliates does business and/or markets its products and services, engage in
activities competitive with, nor render services to any firm or business engaged
or about to become engaged in the Business of the Employer. The Business of the
Employer includes, but is not limited to, the following businesses: (i) the
third party prescription drug claims processing business; (ii) the design,
development or marketing of or consulting as to, prescription drug benefit
plans; (iii) the provision of mail service pharmacy (including all those
products and services that are presently or hereafter marketed by the Employer,
or that are in the development state at the time of termination of my employment
and are actually marketed by the Employer and/or its affiliates thereafter);
(iv) the collection, analysis and/or sale of data relating to prescription drug
utilization; (v) the pharmacy benefit management and disease management
businesses; (vi) the organization and administration of retail pharmacy
networks; and (vii) any other business in which the Employer and/or any of its
affiliates is then engaged as to which I have involvement in the course of my
employment hereunder and/or acquired or received Confidential Information,
(hereinafter collectively, the "Business of the Employer"). In addition, I will
not have an equity interest in any such firm or business other than as a 1% or
less shareholder of a public corporation. The restrictions contained in this
paragraph 4 shall not extend to pharmaceutical manufacturers, other than those
entities which include businesses competing with Merck-Medco Managed Care,
L.L.C., or its subsidiaries.

5. Restrictions Against Solicitation and Inducement. During my employment and
for a period of twelve (12) months following the termination of my employment, I
will not, directly or indirectly: (i) solicit or contact any customer or
targeted potential customer of the Employer and/or its affiliates upon whom I
called or whom I solicited or with whom I became acquainted after commencement
of my employment; (ii) induce or attempt to induce, any employees, agents or
other consultants of the Employer and/or its affiliates to do anything from
which I am restricted by reason of this Agreement; (iii) offer or aid others to
offer employment to any employees, agents, or consultants of the Employer and/or
its affiliates; or (iv) provide services to any customer or otherwise interfere
with or disrupt any contractual or potential contractual relationship between
any customer and the Employer and/or its affiliates.

6. Compliance Not Contingent Upon Additional Consideration. I have not been
promised, and I shall not claim, any additional or special payment for any
of the covenants and agreements contained in this Agreement.

7. Employment Status. This Agreement does not constitute a contract of
employment or an implied promise to continue my employment or status with the
Employer; nor does this Agreement affect my rights or the rights of the Employer
to terminate my employment status at any time with or without cause.

8. Severability. I acknowledge that the terms of this Agreement are fair and
reasonable at the date signed by me. However, in light of the possibility of a
change of conditions or differing interpretations by a court of what is fair and
reasonable, I agree that if any one or more of the terms, provisions, covenants,
or restrictions of this Agreement shall

<PAGE>

be determined by a court of competent jurisdiction to be invalid, void, or
unenforceable, the remainder of the terms, provisions, covenants, and
restrictions of this Agreement shall remain in full force and effect and shall
in no way be affected, impaired, or invalidated. Further, if any one or more of
the terms, provisions, covenants or restrictions contained in this Agreement
shall for any reason be determined by a court of competent jurisdiction to be
excessively broad as to duration, geographical scope, activity, or subject, it
shall be construed, by limiting or reducing it, so as to be enforceable to the
maximum extent compatible with then applicable law.

9. Successors and Assigns. This Agreement shall be binding upon my heirs,
executors, and administrators, and shall inure to the benefit of and be
binding upon the successors and assigns of the Employer.

10. Non-Waiver/Remedies. Any waiver by the Employer of a breach of any provision
or covenant in this Agreement shall not operate or be construed as a waiver of
any subsequent breach or of any rights which the Employer may otherwise have. I
acknowledge that breach of this Agreement would cause grave and irreparable
injury to the Employer that would not be compensable in money damages, and
therefore, in addition to the Company's other express or implied remedies, the
Company shall be entitled to injunctive and other equitable relief to prevent
any actual intended or likely injuries that may result from such breach.
However, nothing in this Agreement shall limit any other right or remedy to
which the Employer may be entitled.

11. Governing Law. This Agreement shall be construed in accordance with and
governed for all purposes by the laws and public policy of the State of New
Jersey, without regard to principles of conflict of laws.

/s/ [Illegible]                           /s/ Timothy C. Wentworth
--------------------------------------    --------------------------------
Witness                                   Employee

December 10, 1998
------------------------------------      Print Name: Timothy C. Wentworth
Date                                                  ---------------------<PAGE>

                                                                   EXHIBIT 10.16

                             KEY EMPLOYEE AGREEMENT
                             ----------------------

     In consideration of my employment by Merck-Medco Managed Care, L.L.C.,
and/or any of its corporate parents, subsidiaries, divisions or affiliates, or
the successors or assigns of any of the foregoing (hereinafter collectively
referred to as "Employer"), I hereby agree as follows:

1. Property Rights. All data, concepts, ideas, designs, findings, discoveries,
inventions, improvements, advances, methods, formulas, plans, programs (computer
or otherwise), practices, techniques, developments and relationships with
customers and prospective customers relating in any way to the present and/or
contemplated products, services, or business of the Employer (collectively
"Developments") that I may conceive, make, invent or suggest during or as a
result of my employment by the Employer, whether acting alone or in conjunction
with others, shall be the sole and absolute property of the Employer free of any
rights of any kind on my part. I will promptly make full disclosure of all
Developments to the Employer. I agree to do all acts and things (including,
among others, the execution and delivery of patent and copyright applications
and instruments of assignment) deemed by the Employer to be necessary or
desirable at any time in order to effect the full assignment to the Employer of
my rights, if any, to such Developments.

2. Covenant Against Use and Disclosure. I recognize that in connection with my
employment, I may learn of, and/or it may be desirable or necessary for the
Employer to disclose to me confidential information ("Confidential
Information"). I understand that Confidential Information is valuable and
proprietary to the Employer (or to third parties that have entrusted the
Confidential Information to the Employer). I agree that, except as required by
my employment with the Employer, I will not at any time, directly or indirectly,
use, publish, communicate, describe, disseminate, or otherwise disclose
Confidential Information to any person or entity without the express prior
written consent of the Employer. The term Confidential Information shall
include, but shall not be limited to: (a) customer lists, lists of potential
customers and details of agreements with customers; (b) acquisition, expansion,
marketing, financial and other business information and plans of the Employer;
(c) research and development; (d) data concerning usage of prescription drugs
and any other data compiled by the Employer; (e) computer programs; (f) sources
of supply; (g) identity of specialized consultants and contractors and
Confidential Information developed by them for the Employer; (h) purchasing,
operating and other cost data; (i) special customer needs, cost and pricing
data; (j) employee information (including, but not limited to, personnel,
payroll, compensation and benefit data and plans); and (k) patient records and
data, including all such information recorded in manuals, memoranda,
projections, minutes, plans, drawings, designs, formula books, specifications,
computer programs and records, whether or not legended or otherwise identified
by the Employer as Confidential Information, as well as such information that is
the subject of meetings and discussions and not recorded. Confidential
Information shall not include such information that is generally available to
the public (other than as a result of a disclosure by me or others in violation
of law or agreement) or that is disclosed to me by a third party under no
obligation to keep such information confidential.

3. Return of Documents. Upon the termination of my employment with the Employer
or upon the Employer's request, whichever is sooner, I shall immediately deliver
to the Employer all plans, designs, drawings, specifications, listings, manuals,
records, notebooks, computer memory, disks or programs, and similar repositories
of or containing Confidential

<PAGE>

Information or other data relating to the Employer's products, services, or
business then in my possession or control or available from other persons
receiving such documents from me, whether prepared by me or others. I shall not
retain any copies or abstracts of any such documents.

4. Restrictions on Competitive Employment. During my employment, and for a
period of twelve (12) months following the termination of my employment, I will
not (as an individual, principal, agent, employee, consultant, or otherwise),
directly or indirectly in any territory in which the Employer and/or any of its
affiliates does business and/or markets its products and services, engage in
activities competitive with, nor render services to any firm or business engaged
or about to become engaged in the Business of the Employer. The Business of the
Employer includes, but is not limited to, the following businesses: (i) the
third party prescription drug claims processing business; (ii) the design,
development or marketing of or consulting as to, prescription drug benefit
plans; (iii) the provision of mail service pharmacy (including all those
products and services that are presently or hereafter marketed by the Employer,
or that are in the development state at the time of termination of my employment
and are actually marketed by the Employer and/or its affiliates thereafter);
(iv) the collection, analysis and/or sale of data relating to prescription drug
utilization; (v) the pharmacy benefit management and disease management
businesses; (vi) the organization and administration of retail pharmacy
networks; and (vii) any other business in which the Employer and/or any of its
affiliates is then engaged as to which I have involvement in the course of my
employment hereunder and/or acquired or received Confidential Information,
(hereinafter collectively, the "Business of the Employer"). In addition, I will
not have an equity interest in any such firm or business other than as a 1% or
less shareholder of a public corporation. The restrictions contained in this
paragraph 4 shall not extend to pharmaceutical manufacturers, other than those
entities which include businesses competing with Merck-Medco Managed Care,
L.L.C., or its subsidiaries.

5. Restrictions Against Solicitation and Inducement. During my employment and
for a period of twelve (12) months following the termination of my employment, I
will not, directly or indirectly: (i) solicit or contact any customer or
targeted potential customer of the Employer and/or its affiliates upon whom I
called or whom I solicited or with whom I became acquainted after commencement
of my employment; (ii) induce or attempt to induce, any employees, agents or
other consultants of the Employer and/or its affiliates to do anything from
which I am restricted by reason of this Agreement; (iii) offer or aid others to
offer employment to any employees, agents, or consultants of the Employer and/or
its affiliates; or (iv) provide services to any customer or otherwise interfere
with or disrupt any contractual or potential contractual relationship between
any customer and the Employer and/or its affiliates.

6. Compliance Not Contingent Upon Additional Consideration. I have not been
promised, and I shall not claim, any additional or special payment for any
of the covenants and agreements contained in this Agreement.

7. Employment Status. This Agreement does not constitute a contract of
employment or an implied promise to continue my employment or status with the
Employer; nor does this Agreement affect my rights or the rights of the Employer
to terminate my employment status at any time with or without cause.

8. Severability. I acknowledge that the terms of this Agreement are fair and
reasonable at the date signed by me. However, in light of the possibility of a
change of conditions or differing interpretations by a court of what is fair and
reasonable, I agree that if any one or more of the terms, provisions, covenants,
or restrictions of this Agreement shall

<PAGE>

be determined by a court of competent jurisdiction to be invalid, void, or
unenforceable, the remainder of the terms, provisions, covenants, and
restrictions of this Agreement shall remain in full force and effect and shall
in no way be affected, impaired, or invalidated. Further, if any one or more of
the terms, provisions, covenants or restrictions contained in this Agreement
shall for any reason be determined by a court of competent jurisdiction to be
excessively broad as to duration, geographical scope, activity, or subject, it
shall be construed, by limiting or reducing it, so as to be enforceable to the
maximum extent compatible with then applicable law.

9. Successors and Assigns. This Agreement shall be binding upon my heirs,
executors, and administrators, and shall inure to the benefit of and be
binding upon the successors and assigns of the Employer.

10. Non-Waiver/Remedies. Any waiver by the Employer of a breach of any provision
or covenant in this Agreement shall not operate or be construed as a waiver of
any subsequent breach or of any rights which the Employer may otherwise have. I
acknowledge that breach of this Agreement would cause grave and irreparable
injury to the Employer that would not be compensable in money damages, and
therefore, in addition to the Company's other express or implied remedies, the
Company shall be entitled to injunctive and other equitable relief to prevent
any actual intended or likely injuries that may result from such breach.
However, nothing in this Agreement shall limit any other right or remedy to
which the Employer may be entitled.

11. Governing Law. This Agreement shall be construed in accordance with and
governed for all purposes by the laws and public policy of the State of New
Jersey, without regard to principles of conflict of laws.

/s/  [Illegible]                          /s/  Sandra E. Peterson
-------------------------------------     --------------------------------
Witness                                   Employee

December 21, 1998
------------------------------------      Print Name: Sandra E. Peterson
Date                                                  --------------------

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