Document:

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                                                                   EXHIBIT 10.13

                                Merck & Co., Inc.

                   Amendment to Conditions of Employment

          All employees, upon acceptance of employment with Merck & Co., Inc.
(the "Company"), are required to sign the Company's standard "Conditions of
Employment" agreement regarding matters such as confidentiality, ownership of
inventions, and Company policies and regulations. A copy of the Conditions of
Employment agreement you signed is attached for your reference. Employees of
Merck-Medco Managed Care, L.L.C. (with its subsidiaries, collectively "Medco")
enter into agreements which contain non-competition, non-solicitation, and other
undertakings. As a result of the merger of Medco with Merck, and in
consideration of your having been exposed to, and in the future being exposed
to, confidential information concerning Medco and the "Business" as defined
below, it is necessary to request Merck employees who work for Medco to also
agree to non-competition and non-solicitation provisions. Accordingly, the
following paragraphs 8, 9, 10 and 11 will be incorporated into and made part of
your "Conditions of Employment" agreement upon your signature to this Amendment:

          8.   During my employment at Medco and for a period of one (1)
               year after the termination of such employment, for any
               reason, absent the Company's express prior written approval,
               I will not (as an individual, principal, agent, employee,
               consultant, or otherwise), directly or indirectly, in any
               territory that Medco does business and/or markets its
               products and services, engage in any activities that are
               competitive with, nor render services to any firm or
               business engaged or about to become engaged in competition
               with Medco, which includes, but is not limited to: (i) the
               third party prescription drug claims processing business;
               (ii) the marketing of or consulting as to prescription drug
               benefit plans; (iii) the pharmacy benefit management or
               disease management businesses; (iv) the organization and
               administration of retail pharmacy networks; (v) the
               provision of prescription drugs through mail service; and/or
               (vi) any other business in which Medco is then engaged as to
               which I have acquired confidential information (hereinafter
               collectively the "Business"). 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. This
               Agreement does not prevent my employment with a prescription
               pharmaceutical company, a part of which is engaged in the
               Business, so long as my responsibilities do not include any
               activity competitive with the Business, and I so certify to
               Medco in writing on a quarterly basis during the one-year
               term specified above.

          9.   During my employment at Medco and for a period of two (2) years
               after the termination of such employment, for any reason, I will
               not, on behalf of myself or any other person, firm, or
               organization, directly or indirectly: (i) induce, or attempt to
               induce, any employees, agents, or consultants of Medco or the
               Company to do anything from which I am restricted by reason
               hereof; (ii) offer or aid others to offer employment to any
               employees, agents or consultants of Medco or the Company who are
               involved in the Business; and/or (iii) contact or solicit any of
               Medco's or the Company's customers or targeted potential
               customers for the purpose of offering products or services that
               directly or indirectly compete or interfere with the Business.

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          10.  (a) In consideration of my agreement and the restrictions
               contained in this Amendment to the "Conditions of Employment"
               agreement, the Company agrees: (i) if, while I am employed at
               Medco, the Company terminates my employment for reasons other
               than cause and I am not then eligible for retirement from active
               service, I shall be entitled to twelve (12) monthly payments at
               my then monthly base rate, subject to withholding and any
               deductions for benefit coverage. For purposes of this Agreement,
               I will be deemed an inactive employee until the earlier of the
               expiration of such monthly payment period or until I obtain
               employment elsewhere. During such inactive employee status, I may
               continue to participate in any benefit plans in which I
               participated at the time of my termination other than any
               disability plans; (ii) if, while I am employed at Medco, the
               Company terminates my employment for reasons other than cause and
               I retire from active service, then I shall be entitled to the
               above number of monthly payments at my then monthly base rate,
               subject to withholding; (iii) should I die prior to receiving all
               monthly payments to which I am entitled to hereunder, any
               remaining payments shall be paid in a lump sum to my estate.

               (b) This Agreement shall be construed in accordance with and
               governed for all purposes by the laws and public policy of New
               Jersey, without regard to principles of conflict of laws. If I
               breach any of the provisions of the "Conditions of Employment"
               agreement (including this Amendment), then, in addition to any
               other rights or remedies of the Company, the Company shall have
               no obligation to make any monthly payments to me and any status
               as an inactive employee will then terminate immediately.

          11.  The term "Company" as used in the "Conditions of Employment"
               agreement (including this Amendment) shall be deemed to include
               Medco.

          The provisions of paragraphs 8 and 9 shall be construed, and limited
or reduced if necessary, by a court so as to be enforceable to the maximum
extent permitted by applicable law and, without limiting any remedy available,
shall be enforceable by injunctive or equitable relief.

          Please sign and return a copy of this Amendment confirming your
agreement hereto.

                                /s/ Richard Clark

                                --------------------------------------
                                  Richard Clark

                                January 29, 1999

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

Enclosure

                                /s/ Bert Weinstein

                                --------------------------------------
                                Signature of Company Representative

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                             MERCK & CO., INC.

                            CONDITIONS OF EMPLOYMENT

Prepare in Duplicate

          The purpose of this statement is to define the conditions which a new
employee accepts when he joins Merck & Co., Inc. ("the Company"). The employee's
signature indicates that he understands this statement and agrees to abide by
it. A copy is provided to the new employee in order to avoid any possible
misunderstandings regarding the provisions of this agreement.

          1.   I will abide by all the policies and regulations of the
               Company, will subscribe to the Company's Group Life
               Insurance Plan and will join and qualify under the Company's
               Retirement Income Plan as soon as I am eligible under the
               terms of the Plan. I have received and read booklets
               describing the Group Life Insurance Plan and the Company's
               Retirement Income Plan. I also agree that I will be subject
               to Workmen's Compensation Laws of the state or states in
               which I will be employed by the Company.

          2.   I will devote my best efforts to the service of the Company, will
               perform such duties as may be assigned to me and will not engage
               in other employment and/or activities that conflict with or
               impair my obligations as an employee of the Company.

          3.   I will not, during or at any time after the period of my
               employment by the Company, use for myself or others or
               divulge or convey to others any information, knowledge, data
               or property relating to the Company's business in any way
               obtained by me while employed by the Company other than
               published material properly in the public domain unless
               authorized by the Company in writing or by established
               Company procedures. This includes but is not limited to
               information, knowledge, data or property concerning any
               process, apparatus or product manufactured, used, developed,
               investigated or considered by the Company.

          4.   All memoranda, notes, records, papers or other documents
               (and all copies thereof) relating to the Company's business
               and all property associated therewith (such as but not
               confined to organisms, compounds and models) in any way
               obtained by me while employed by the Company shall be the
               Company's property and shall be delivered by me to the
               Company on termination of employment or at any time on the
               Company's request together with my written certification of
               compliance. This includes but is not limited to such
               documents and property concerning any process, apparatus or
               product manufactured, used, developed, investigated or
               considered by the Company.

          5.   All inventions or discoveries relating to the Company's business
               which I conceive or make while employed by the Company shall be
               the Company's property. Any invention

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               relating to the Company's business disclosed by me within one
               year following the termination of this employment shall be deemed
               to fall within this provision, unless proved to have been
               conceived and made following such termination.

          6.   When requested by the Company, whether during or subsequent
               to this employment, I will execute patent applications and
               other instruments considered necessary by the Company to
               apply for and obtain Letters Patent of the United States and
               foreign countries covering such inventions or discoveries
               and will make assignments and execute other instruments
               necessary to convey to the Company ownership and exclusive
               rights in such inventions, discoveries, patent applications
               and patents.

          7.   The Company shall bear all expenses connected with such patents,
               patent applications and maintenance of patent protection, and if
               services in connection therewith are performed by me at the
               request of the Company after termination of this employment, the
               Company shall pay reasonable compensation for such
               post-employment services.

Signature of New Employee /s/ Richard T. Clark, Jr.     Date August 14, 1972
                          -----------------------------      ---------------
                            Reports to D. O. Kennedy

Signature of Company Representative /s/ H. J. Hurst     Date August 14, 1972
                                    -------------------      ---------------<PAGE>
                                                                   EXHIBIT 10.14

                              EMPLOYMENT AGREEMENT
                              --------------------

     This EMPLOYMENT AGREEMENT ("Agreement"), dated as of March 17, 2003, is
entered into by and between Medco Health Solutions, Inc. ("Medco Health"), a
Delaware corporation with offices at 100 Parsons Pond Drive, Franklin Lakes, New
Jersey 07417 and David B. Snow, Jr. ("the Executive"). Medco Health is currently
a wholly owned subsidiary of Merck & Co., Inc. ("Merck"). Merck has publicly
announced its intention to establish Medco Health as a separate, public company
in mid-2003, subject to market conditions.

     1. Employment. Medco Health hereby agrees to employ the Executive during
the Employment Period subject to the terms of this Agreement, and, provided that
this Agreement has not terminated prior to March 31, 2008, thereafter as an
employee-at-will. Unless prevented by sickness or disability, the Executive
shall use his best and most diligent efforts to promote the interests of Medco
Health and its affiliates and shall devote his full business time and attention
to his employment under this Agreement. The Executive will not, without the
prior written approval of Medco Health's Board of Directors, engage in any other
business activity that would interfere with the performance of his duties,
services and responsibilities hereunder or that is in violation of policies
established by Medco Health; provided, however, that this Agreement shall not be
interpreted as prohibiting the Executive from managing his personal affairs or
engaging in charitable or civic activities. For purposes of this Agreement,
"Employment Period" shall mean a period commencing on March 31, 2003 and ending
on the sooner of March 31, 2008 or the date on which this Agreement is
terminated under paragraph 10 below.

     2. Title. Upon his commencement of employment at Medco Health, the
Executive's title shall be Chief Executive Officer and President, and he shall
be a member of Medco Health's Board of Directors ("the Board of Directors"). The
Executive shall report to the Board of Directors as it may be constituted from
time to time. Within three months following the commencement of his employment
with Medco Health, the Executive shall also be appointed Chairman of the Board
of Directors and shall continue to report to the Board of Directors. The
Executive shall have powers, responsibilities and authorities of Chief Executive
Officer, President, Director and, upon being so named, of Chairman of the Board
of Directors, as established by custom and practice, or as otherwise determined
by the Board of Directors.

     3. Compensation. As compensation for the Executive's services under this
Agreement, Medco Health shall pay the Executive a base salary at the rate of
$800,000 per year, payable in equal installments in accordance with Medco
Health's practice. Beginning in the first quarter of 2004, the Executive's base
salary then in effect and other components of compensation shall be reviewed
and, if appropriate, revised by the Board of Directors no less frequently than
annually, provided that the Executive's annual base salary shall not be less
than $800,000 during the Employment Period. The Executive shall not participate
in such compensation review or revision.

     4. Annual Incentive. The Executive shall be eligible to participate in
Medco Health's annual incentive bonus plan in accordance with its terms and
conditions. During the

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Employment Period, the target amount of such bonus shall be 100 percent of the
Executive's base salary at the end of the prior calendar year. The actual amount
of the annual bonus shall be determined by the Board of Directors considering
Medco Health's and the Executive's performance. For award year 2003, the
Executive shall be eligible for a bonus payable in or around March 2004. The
Executive shall not participate in deliberations or determinations of the Board
of Directors concerning his bonus.

     5. Long-Term Incentives. The Executive shall be eligible to receive annual
long-term incentives. The first such long-term incentives shall be provided to
the Executive in the first quarter of 2004. In the first quarter of 2004, the
target aggregate economic value of all long-term incentives provided to the
Executive shall be $4,800,000 (600% of the Executive's starting base salary of
$800,000). By way of example, if only a nonqualified stock option is to be
granted, the number of shares subject to such option is determined by dividing
the $4,800,000 by the Black-Scholes value of a nonqualified stock option for one
share of Medco Health stock. Such Black-Scholes value shall be determined using
the standard valuation methodology, based on the maximum term of the option
award. The resulting number of shares shall then become the target number of
shares to be used in determining future stock option grants or other long-term
incentives. By way of example, if the Board of Directors implements an alternate
long-term incentive plan to replace 25% of the stock option value, the
alternative long-term incentive must have an economic value at grant that is
approximately equivalent in value to the forgone stock options. In determining
the economic equivalent value of forgone stock options, such value shall be
determined based on reported value for financial disclosure purposes and, to the
extent such awards are granted to other senior executives, in accordance with
the valuation procedures used to determine awards for such individuals. The date
such long-term incentives are granted shall generally be the same as the date
long-term incentives are granted to other senior executives of Medco Health. The
form, amount and grant date of any long-term incentives shall be determined by
the Board of Directors. The Executive shall not participate in such
determination.

     6. Equity-Based Awards upon the Earlier of IPO or Spin-Off. Upon the
effective date of the earlier of the (i) initial public offering of Medco Health
("IPO") or (ii) the complete distribution to its stockholders by Merck of the
shares of Medco Health ("Spin-Off"), the Executive shall be granted:

     (a)  a nonqualified stock option for the number of shares of Medco Health
          determined by dividing $5,000,000 by the Black-Scholes value of a
          nonqualified stock option for one share of Medco Health stock on the
          grant date at the exercise price set on the grant date. For such
          purposes, Black-Scholes value shall be determined using the full term
          of the option award and the average stock price volatility of selected
          industry peers; and

     (b)  a grant of restricted stock units for the number of shares of Medco
          Health determined by dividing $2,500,000 by the stock price of Medco
          Health shares on the day of the grant.

     If the grants are made upon the effective date of the IPO, the per share
option exercise price and the stock price used to determine the restricted stock
units shall be the IPO price of

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Medco Health common stock. If the grants are made upon the Spin-Off, the per
share option exercise price and the stock price used to determine the restricted
stock units shall be determined on such date by a method to be determined by the
Board of Directors. The Executive shall not participate in such determination.

     The stock option and restricted stock units granted pursuant to this
paragraph shall vest on the third anniversary of the grant date. The stock
option and restricted stock units shall have terms as described in Attachment
"A" annexed hereto.

     7. Participation in Other Benefit Plans. As an employee of Medco Health,
the Executive shall be eligible to participate in Medco Health's employee
benefit plans for its salaried employees on a basis comparable to Medco Health's
other most senior executives, including but not limited to its medical, dental,
disability, life insurance, pension and savings plans, subject to any
contribution requirements applicable to participants of such plans and programs.
The Executive shall be entitled to take five weeks of paid vacation during each
calendar year.

     8. Other Benefits.

          (a)  Medco Health shall pay for the cost of personal financial
               planning to the Executive by a financial counselor of the
               Executive's choice, provided that the cost to be borne by Medco
               Health shall not exceed $15,000 in 2003 and $10,000 in subsequent
               years of the Employment Period.

          (b)  During the Employment Period, Medco Health shall pay the
               Executive a monthly automobile allowance of $1,885.

          (c)  Upon submission of itemized invoices indicating time and charges,
               Medco Health shall reimburse the Executive for reasonable
               attorneys' fees up to $25,000 incurred in the drafting,
               negotiation and execution of this Agreement.

          (d)  During the Employment Period, the Executive is authorized to
               incur reasonable business expenses in carrying out his duties and
               responsibilities under this Agreement. Medco Health shall
               reimburse him for all such reasonable business expenses subject
               to and in accordance with the terms and conditions of Medco
               Health's policies applicable to its other senior executives.

          (e)  Medco Health shall indemnify and hold harmless the Executive in
               the same amount and to the same extent as its other senior
               officers and directors for any action or inaction of the
               Executive while serving as an officer or director of Medco Health
               or any of its affiliates or, at Medco Health's request, as an
               officer or director of any other entity or as a fiduciary of any
               benefit plan. Medco Health shall cover the Executive under
               directors and officers liability insurance both during and, while
               potential liability exists, after termination of

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               employment in the same amount and to the same extent as Medco
               Health covers its other senior officers and directors.

     9. Full Settlement. Medco Health's obligation to make the payments or grant
the benefits provided for in this Agreement and otherwise to perform its
obligations hereunder shall not be affected by any set-off, counterclaim,
recoupment, defense or other claim, right or action which Medco Health may have
against the Executive or others, except as otherwise provided in this Agreement.
In no event shall the Executive be obligated to seek other employment or take
any other action by way of mitigation of the amounts payable or benefits granted
to the Executive under any of the provisions of this Agreement and such amounts
or benefits shall not be reduced because the Executive obtains other employment,
except as otherwise provided in this Agreement, except that any continued
healthcare benefits provided for in subparagraphs 10(b) and 10(c) shall be
secondary to any coverage provided to the Executive and his spouse and eligible
dependents by any such other employment.

     10. Termination.

          (a)  By Medco Health for Cause. Upon written notice to the Executive
               specifying the basis for such action, Medco Health may discharge
               the Executive and terminate this Agreement for Cause. As used in
               this paragraph, "Cause" shall exist only if, after reasonable
               investigation, a majority of the Board of Directors (excluding
               the Executive), after providing the Executive (and his counsel,
               if he so chooses) a reasonable opportunity to be heard, finds
               that one or more of the following conditions exists: (i) an act
               or acts of personal dishonesty or misrepresentation made by the
               Executive and intended to result in substantial personal
               enrichment of the Executive at the expense of Medco Health; (ii)
               demonstrably willful and deliberate violations by the Executive
               of the Executive's obligations under this Agreement; (iii) the
               Executive's gross neglect (other than any such failure resulting
               from incapacity due to physical or mental illness) or gross
               misconduct in carrying out his duties resulting, in either case,
               in material economic harm to Medco Health; (iv) the conviction
               of, or plea of nolo contendere by, the Executive of a felony.
               Upon Medco Health's termination of this Agreement for Cause: the
               Executive shall forfeit any remaining equity awards granted under
               paragraphs 5 and 6 hereof (whether or not = vested) have not yet
               been paid, been exercised or become unrestricted (as applicable)
               as of the date of such termination; Medco Health shall have no
               obligation to provide severance or separation pay to the
               Executive; and Medco Health shall be relieved, as of the
               effective date of the termination, from any further salary or
               compensation payments to the Executive other than the payment of
               accrued or vested benefits. For purposes of the foregoing
               sentence, the annual bonus described in paragraph 4, and equity
               and incentive awards described in paragraphs 5 and 6, shall not
               be deemed accrued or vested benefits.

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          (b)  By Medco Health without Cause or by Reason of Disability or by
               the Executive for Good Reason. Medco Health on written notice to
               the Executive may discharge the Executive and terminate this
               Agreement without Cause at any time during the Employment Period.
               Medco Health on written notice to the Executive may discharge the
               Executive and terminate this Agreement at any time during the
               Employment Period by reason of Disability which, for purposes of
               this Agreement, means the failure of the Executive to carry out
               substantially and effectively Executive's duties and
               responsibilities hereunder for a period in excess of eight
               consecutive weeks or twelve weeks in any six-month consecutive
               period. The Executive may terminate this Agreement during the
               Employment Period upon written notice to Medco Health, for Good
               Reason which, for purposes of this paragraph, will arise only (i)
               if Medco Health fails to appoint the Executive as Chairman of the
               Board of Directors within three months after his employment by
               Medco Health has commenced, provided that such notice must be
               received by Medco Health's Board of Directors no later than 120
               days after such employment has commenced, (ii) if Medco Health
               has not become a separate public company by December 31, 2004,
               provided that such written notice must be received by Medco
               Health's Board of Directors no later than January 31, 2005, (iii)
               if Medco Health takes any action that results in a substantial
               and material diminution in the Executive's position, authority,
               duties or responsibilities, excluding for this purpose an
               isolated, insubstantial and inadvertent action not taken in bad
               faith and which is remedied by Medco Health promptly after
               receipt of written notice thereof given by the Executive, or if
               the Executive is required to report to anyone other than the full
               Board of Directors, provided that written notice must be received
               by the Board of Directors within 30 days of such diminution or
               change in reporting, whichever is applicable, or (iv) if Medco
               Health fails to comply with and satisfy paragraph 15 of this
               Agreement, provided that such written notice must be received by
               the Board of Directors within 60 days of such initial failure or
               noncompliance. Upon termination of this Agreement during the
               Employment Period either by Medco Health without Cause or by
               reason of Disability or by the Executive for Good Reason (as
               described above), Medco Health shall be relieved of any further
               salary or compensation payments to the Executive other than the
               payment of accrued or vested benefits. Notwithstanding the
               preceding sentence, the Executive shall also be entitled to
               receive, in return for a general release and waiver of claims, a
               severance payment (subject to appropriate payroll and tax
               withholding and deductions) equal in amount to twice the sum (one
               times the sum in the case of termination by reason of Disability)
               of the Executive's current (i.e., at the time of termination)
               annual base pay plus the last annual bonus he received from Medco
               Health prior to such termination, and payment for 12 months by
               Medco Health of the premium cost of COBRA continuation coverage
               for him and his spouse and dependents who are eligible for COBRA
               continuation coverage. The foregoing severance payment shall be
               in lieu of any other severance payment or arrangement under any
               Medco Health plan, policy or practice, and shall be paid in 24
               equal monthly installments (12

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               equal monthly installments in the case of termination by reason
               of Disability) beginning on the last day of the month following
               the month in which the Executive's employment with Medco Health
               terminated; provided, however, that upon the Executive's
               post-employment substantial or material breach of any of his
               obligations set forth in paragraph 11 below, or upon Medco
               Health's learning after the termination of the Executive's
               employment that the Executive either breached any such obligation
               during the Employment Period, or engaged in conduct during the
               Employment Period that would have warranted the termination of
               this Agreement for Cause under paragraph 10(a) hereof, Medco
               Health shall be relieved of the obligation to make any, or any
               further, severance or COBRA payment or payments under this
               subparagraph 10(b).

          (c)  By Medco Health Following a Change in Control. If within one year
               of a "Change in Control" as defined in Attachment "B" annexed
               hereto, the Executive's employment with Medco Health is
               terminated by the Company without Cause, Medco Health shall be
               relieved of any further salary or compensation payments
               hereunder, except that the Executive shall be entitled to
               receive, in return for a general release and waiver of claims, a
               lump sum severance payment (subject to appropriate payroll and
               tax withholding and deductions) equal in amount to three times
               the sum of the Executive's current annual base pay plus the last
               annual bonus he received from Medco Health prior to such
               termination, and payment for 12 months by Medco Health of the
               premium cost of COBRA continuation coverage for him and his
               spouse and dependents who are eligible for COBRA continuation
               coverage. The foregoing severance payment shall be in lieu of any
               other severance payment or arrangement under any Medco Health
               plan, policy or practice. Stock-based incentives shall be
               governed by their terms. If it shall be determined that any
               payment to the Executive would be subject to the excise tax
               imposed by Section 4999 of the Internal Revenue Code, then the
               Executive shall receive a "Tax Gross-Up Payment." A Tax Gross-Up
               Payment means an amount payable to the Executive such that, after
               payment of excise taxes on such amount, there remains a balance
               sufficient to pay the excise taxes being reimbursed.

          (d)  Resignation from the Board of Directors. If the Executive's
               employment with Medco Health ends for any reason, and the Board
               of Directors requests that the Executive resign from the Board of
               Directors, the Executive agrees to resign from the Board of
               Directors immediately upon receipt of such request.

          (e)  Continuing Obligations. The termination of this Agreement shall
               not affect any of the Executive's post-employment obligations
               that may arise under paragraph 11 below.

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     11. Noncompete, Nonsolicitation, Developments, Nondisparagement and
Confidentiality. In consideration for the compensation and benefits provided
pursuant to this Agreement, the Executive agrees:

          (a)  While the Executive is an employee of Medco Health and for a
               period of two years after his employment by Medco Health
               terminates, the Executive will not (as an individual, principal,
               agent, employee, consultant or otherwise) for any reason without
               Medco Health's prior written consent, directly or indirectly in
               any territory in which Medco Health 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 competition with,
               the business of Medco Health, which 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 Medco Health, or that are in the development stage at
               the time of termination of the Executive's employment at Medco
               Health and are actually marketed by Medco Health and/or its any
               of 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
               business whether such business is conducted through mail service,
               retail pharmacy networks or other means, including but not
               limited to the internet and other types of electronic
               transmission; (vi) the organization and administration of retail
               pharmacy networks; and (vii) any other business in which Medco
               Health and/or its any of its affiliates is then engaged
               (hereinafter collectively, the "Business of Medco Health"). In
               addition, the Executive agrees not to have an equity interest in
               any such firm or business other than a 1% or less shareholder of
               a public corporation. Notwithstanding the foregoing, after the
               Executive's employment by Medco Health terminates, nothing herein
               shall be construed to prevent or restrict the ability of the
               Executive to perform services (as an individual, principal,
               agent, employee, officer, director, consultant or otherwise) for
               any business or entity primarily engaged in the operation,
               management, financing or marketing of health insurance or health
               maintenance organizations, provided that such business or entity
               is not engaged in the third party prescription drug claims
               processing business or the pharmacy benefit management business.

          (b)  During the Executive's employment with Medco Health and for a
               period of two years following the termination of his employment
               with Medco Health, he will not, directly or indirectly, (i)
               solicit or contact any customer or targeted potential customer of
               Medco Health and/or any of its affiliates for the purpose of
               offering products or services that, directly or indirectly,
               compete or interfere with the Business of Medco Health and/or its
               any of its affiliates, (ii) induce or attempt to induce, any
               employees, agents or other consultants of Medco Health and/or its
               any of its affiliates to do anything from which the

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               Executive is restricted by reason of this Agreement, (iii) offer
               or aid others to offer employment to any employees, agents, or
               other consultants of Medco Health and/or its any of 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 Medco Health
               and/or any of its affiliates.

          (c)  The Executive agrees that, during his employment and following
               the termination of his employment with Medco Health, he will not
               disparage Medco Health, any of its affiliates, products,
               officers, employees, former employees, representatives or agents
               in any way whatsoever.

          (d)  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 Medco Health (collectively
               "Developments") that the Executive may conceive, make, invent or
               suggest during or as a result of his employment by Medco Health,
               whether acting alone or in conjunction with others, shall be the
               sole and absolute property of Medco Health free of any rights of
               any kind on the part of the Executive. The Executive shall
               promptly make full disclosure of all Developments to Medco
               Health. He agrees to do all acts and things (including, among
               others, the execution and delivery of patent and copyright
               applications and instruments of assignment) deemed by Medco
               Health to be necessary or desirable at any time in order to
               effect the full assignment to Medco Health of his rights, if any,
               to such Developments.

          (e)  The Executive recognizes that, in connection with his employment
               by Medco Health, he may learn of, and/or it may be desirable or
               necessary for Medco Health to disclose to him confidential
               information ("Confidential Information"). He understands that
               Confidential Information is valuable and propriety to Medco
               Health (or to third parties that have entrusted the Confidential
               Information to Medco Health). The Executive agrees that, except
               as required by his employment with Medco Health, he 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 Medco Health. The term Confidential
               Information shall include, but shall not be limited to: (i)
               customer lists, lists of potential customers and details of
               agreements with customers; (ii) acquisition, expansion,
               marketing, financial and other business information and plans of
               Medco Health; (iii) research and development; (iv) data
               concerning usage of prescription drugs and any other data
               compiled by Medco Health; (v) computer programs; (vi) sources of
               supply; (vii) identity of specialized consultants and contractors
               and Confidential Information developed by them for Medco Health;
               (viii) purchasing, operating and other

                                       8

<PAGE>

               cost data; (ix) special customer needs, cost and pricing data;
               (x) employee information (including, but not limited to,
               personnel, payroll, compensation and benefit data and plans); and
               (xi) 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 Medco Health 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 the Executive)
               or that is disclosed to the Executive by a third party under no
               obligation to keep such information confidential.

          (f)  Upon the termination of the Executive's employment with Medco
               Health or upon Medco Health's request, whichever is sooner, the
               Executive shall immediately deliver to Medco Health all plans,
               designs, listings, manuals, records, notebooks, and similar
               repositories of or containing Confidential Information or other
               documents and data relating to Medco Health's products, services,
               or business then in the Executive's possession or control or
               available from other persons receiving such documents from the
               Executive, whether prepared by the Executive or others. The
               Executive shall not retain any copies or abstracts of any such
               documents. Upon the termination of the Executive's employment
               with Medco Health, the Executive shall immediately deliver to
               Medco Health all Medco Health property in his possession or
               control including, but not limited to, computer(s) and office
               equipment.

          (g)  Any substantial or material breach by the Executive of any of the
               post-employment obligations set forth in this paragraph 11, shall
               terminate any further post-employment obligations that Medco
               Health may have relative to providing post-employment
               compensation or benefits to the Executive and shall result in the
               immediate expiration of any outstanding options, vested or
               unvested.

     12. Applicable Law. Any question as to the scope, interpretation and effect
of this Agreement will be resolved under the substantive and procedural laws of
the State of New Jersey and the United States.

     13. Enforceability. All provisions and portions of this Agreement are
severable. If any provision or portion of this Agreement or the application of
any provision or portion of the Agreement shall be determined to be invalid or
unenforceable to any extent or for any reason, all other provisions and portions
of this Agreement shall remain in full force and effect and shall continue to be
enforceable to the fullest and greatest extent permitted by law.

     14. No Representations. The Executive agrees that no promises, other than
the promises in this Agreement, have been made to him by or on behalf of Medco
Health. He agrees that in executing this Agreement he is not relying upon any
statement or representation, other

                                       9

<PAGE>

than those set forth herein, made by or on behalf of Medco Health concerning his
employment by Medco Health.

     15. Successors.

          (a)  This Agreement is personal to the Executive and without the prior
               written consent of Medco Health shall not be assignable by the
               Executive. This Agreement shall inure to the benefit of and be
               enforceable by the Executive's legal representatives.

          (b)  This Agreement shall inure to the benefit of and be binding upon
               Medco Health and its successors and assigns.

          (c)  Medco Health shall require any successor (whether direct or
               indirect, by purchase, merger, consolidation or otherwise) to all
               or substantially all of the business and/or assets of Medco
               Health to assume expressly and agree to perform this Agreement in
               the same manner and to the same extent that Medco Health would be
               required to perform it if no such succession had taken place.

     16. Contingencies. This Agreement is contingent upon the successful (i.e.,
satisfactory to Medco Health) completion of both a pre-employment drug screen
and a background check of the Executive prior to March 31, 2003.

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

                          MEDCO HEALTH SOLUTIONS, INC.

                          By: /s/ Richard T. Clark
                              ---------------------------------------
                                  Richard T. Clark

                          EXECUTIVE

                          /s/ David B. Snow, Jr.
                          ---------------------------------------------
                          David B. Snow, Jr.

                                       10

<PAGE>

                                  ATTACHMENT A

             MEDCO HEALTH SOLUTIONS, INC. 2002 STOCK INCENTIVE PLAN
                        NON-QUALIFIED STOCK OPTION (NQSO)
                           SUMMARY OF CEO GRANT TERMS

This is a summary of the terms applicable to the non-qualified stock option
granted under the Medco Health Solutions, Inc. 2002 Stock Incentive Plan (the
"Plan") pursuant to the Employment Agreement between David B. Snow, Jr. and
Medco Health Solutions, Inc. (the "Employment Agreement"). Different terms may
apply to any other stock option granted under the Plan.

I.  GENERAL INFORMATION

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

Grant Type:                NQSO
Number of Shares:          [TBD]
Option Price:              [TBD]
Grant Date:                [TBD]
Vesting Date:              3rd Anniversary of Grant Date
Expiration Date:           Day before 10th Anniversary of Grant Date

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

This stock option becomes exercisable on the Vesting Date indicated in the
accompanying box. This stock option expires on its Expiration Date, which is the
day before the tenth anniversary of the Grant Date except that, if your
employment with Medco Health Solutions, Inc. ("the Company") ends for any
reason, your right to exercise this stock option will be determined according to
the terms in Section II.

II. TERMINATION OF EMPLOYMENT

A. General Rule. If your employment is terminated for any reason other than
those specified in paragraphs B-F, this stock option, if unvested, will expire
on the date your employment ends; this stock option, if vested, will expire on
the day before the same date of the third month after your employment ends, but
in no event later than the original Expiration Date.

B. Termination for Other Than Cause. If (i) you have been employed by the
Company for at least one year and (ii) prior to the Vesting Date, the Employment
Agreement is terminated by the Company for reason other than (a) Cause (as
defined in the Employment Agreement) or (b) a reason specified in paragraphs C-F
below, then a portion of this stock option will vest on the later of (1) the
first anniversary of the date your employment with the Company ends, or (2) if
the grant is made upon IPO, the date of the distribution by Merck & Co., Inc. of
the remaining shares of the Company (the "Spin-off"), but in no event later than
the original Vesting Date. The vested portion will be 1/3 for termination on any
date after the one year anniversary of the first day of the Employment Period
through the day before the first anniversary of the grant date; 2/3 for
termination on the first anniversary of the grant date through the day before
the second anniversary of the grant date; and fully vested for termination on or
after the second anniversary of the grant date. The unvested portion of this
stock option will expire on the date the Employment Agreement is terminated by
the Company. Any portion of this stock option that is vested as a result of this
paragraph, will expire, in its entirety, the day before the second anniversary
of the date the Employment Agreement is terminated by the Company. If, after the

                                       11

<PAGE>

Vesting Date, the Employment Agreement is terminated by the Company for reason
other than (a) Cause (as defined in the Employment Agreement) or (b) a reason
specified in paragraphs C-F below, then this stock option will expire the day
before the second anniversary of the date the Employment Agreement is
terminated, but in no event later than the original Expiration Date.

C. Retirement. If you retire from service with the Company, this stock option
will continue to become exercisable on the applicable Vesting Date and will
expire on the original Expiration Date.

D. Death. If you die, this stock option, if unvested, will vest on the later of
(i) the date of your death or (ii) if the grant is made upon IPO, the date of
the Spin-off but in no event later than the original Vesting Date. Whether
already vested on the date of your death or vested as a result of your death,
this stock option will expire the day before the third anniversary of your
death, or such earlier date as may be required under applicable non-U.S. law,
but in no event later than the day before the first anniversary of the original
Expiration Date.

E. Gross Misconduct. If your employment is terminated as a result of your gross
misconduct (as determined by the Company), this stock option (to the extent
unexercised and whether vested or unvested) will expire immediately upon such
termination. For purposes of this option, gross misconduct means Cause as
defined in the Employment Agreement.

F. Change in Control. If your employment with the Company is terminated within
one year of a Change in Control (as that term is defined in the Plan), for any
reason other than resignation or one of the reasons specified in paragraphs C-E
above, this stock option, if unvested, will vest on the date of your
termination. Whether already vested on the date of your termination or vested as
a result of your termination, this stock option will expire the day before the
second anniversary of the date your employment with the Company ends, but in no
event later than the original Expiration Date.

III. POST EMPLOYMENT OBLIGATIONS.

If you substantially or materially breach any of the post-employment obligations
set forth in paragraph 11 of the Employment Agreement, this option shall expire
immediately, whether vested or unvested.

IV.  TRANSFERABILITY

This stock option is not transferable and may not be assigned or otherwise
transferred except, under specific terms as determined by the Board of Directors
or its Compensation Committee of the Board, while you hold a position as an
executive officer subject to Section 16 of the Securities Exchange Act of 1934,
or within, twelve (12) months of retirement from, such Section 16 position.

This stock option is subject to the provisions of the Company's 2002 Stock
Incentive Plan and the Rules and Regulations thereunder established by the
Company's Board of

                                       12

<PAGE>
Directors or its Compensation Committee (except where the
terms set forth herein conflict with the Rules and Regulations, in which case
these terms shall control).

<PAGE>

             MEDCO HEALTH SOLUTIONS, INC. 2002 STOCK INCENTIVE PLAN
                           RESTRICTED STOCK UNIT (RSU)
                           SUMMARY OF CEO GRANT TERMS

This is a summary of the terms applicable to the restricted stock unit ("RSU")
granted under the Medco Health Solutions, Inc. 2002 Stock Incentive Plan (the
"Plan") pursuant to the Employment Agreement between David B. Snow, Jr. and
Medco Health Solutions, Inc. (the "Employment Agreement"). Different terms may
apply to any other RSU granted under the Plan.

I. GENERAL INFORMATION

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

Grant Type:           RSU
Number of Shares:     [TBD]
Grant Price:          [TBD]
Grant Date:           [TBD]
Vesting Date:         3rd Anniversary of Grant Date

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

This grant becomes payable on the Vesting Date indicated in the accompanying
box. Payment will be in shares of common stock of Medco Health Solutions, Inc.
("the Company"). If your employment with the Company ends for any reason, your
right to this grant will be determined according to the terms in Section II.

II. TERMINATION OF EMPLOYMENT

A. General Rule. If your employment is terminated for any reason other than
those specified in paragraphs B-E, this grant, if unvested, will be forfeited on
the date your employment ends.

B. Termination for Other Than Cause. If (i) you have been employed by the
Company for at least one year and (ii) prior to the Vesting Date, the Employment
Agreement is terminated by the Company for reason other than (a) Cause (as
defined in the Employment Agreement) or (b) a reason specified in paragraphs C-F
below, then a portion of this grant will vest on the later of (1) the first
anniversary of the date your employment with the Company ends, or (2) if the
grant is made upon IPO, the date of the distribution by Merck & Co., Inc. of the
remaining shares of the Company (the "Spin-off"), but in no event later than the
original Vesting Date. The vested portion will be 1/3 for termination on any
date after the one year anniversary of the first day of the Employment Period
through the day before the first anniversary of the grant date; 2/3 for
termination on the first anniversary of the grant date through the day before
the second anniversary of the grant date; and fully vested for termination on or
after the second anniversary of the grant date. The unvested portion of this
grant will be forfeited on the date the Employment Agreement is terminated by
the Company.

C. Retirement. If you retire from service with the Company, this grant will
continue to vest on the applicable Vesting Date.

                                       14

<PAGE>

D. Death. If you die, this grant, if unvested, will vest on the later of (i) the
date of your death or (ii) if the grant is made upon IPO, the date of the
Spin-off, but in no event later than the original Vesting Date.

E. Gross Misconduct. If your employment is terminated as a result of your gross
misconduct (as determined by the Company), this grant, if unvested, will be
forfeited immediately upon such termination. For purposes of this grant, gross
misconduct means Cause as defined in the Employment Agreement.

F. Change in Control. If your employment with the Company is terminated within
one year of a Change in Control (as that term is defined in the Plan), for any
reason other than resignation or one of the reasons specified in paragraphs C-E
above, this grant, if unvested, will vest on the date of your termination.

III. POST-EMPLOYMENT OBLIGATIONS.

If you substantially or materially breach any of the post-employment obligations
set forth in paragraph 11 of the Employment Agreement, any portion of this grant
that is unvested shall expire immediately.

This grant is subject to the provisions of the Company's 2002 Stock Incentive
Plan and the Rules and Regulations thereunder established by the Company's Board
of Directors or its Compensation Committee (except where the terms set forth
herein conflict with the Rules and Regulations, in which case these terms shall
control).

                                       15

<PAGE>

                                 ATTACHMENT "B"
                                 --------------

     A "Change in Control" shall mean the occurrence during the term of the
Employment Period, but following the complete distribution to its stockholders
by Merck & Co., Inc. ("Merck") of the shares of Medco Health (the "Spin-Off"),
of any one of the following events:

     (a)  An acquisition (other than directly from Medco Health) of any shares
          of Common Stock or other voting securities of Medco Health by any
          "Person" (for purposes of this Section only, as the term "person" is
          used for purposes of Section 13(d) or 14(d) of the Exchange Act),
          immediately after which such Person has "Beneficial Ownership" (within
          the meaning of Rule 13d-3 promulgated under the Exchange Act) of
          twenty percent (20%) or more of either (i) the then outstanding shares
          of Common Stock or (ii) the combined voting power of Medco Health's
          then outstanding voting securities entitled to vote for the election
          of directors (the "Voting Securities"); provided, however, in
          determining whether a Change in Control has occurred, shares of Common
          Stock or Voting Securities which are acquired in a "Non-Control
          Acquisition" (as hereinafter defined) shall not constitute an
          acquisition which would cause a Change in Control. A "Non-Control
          Acquisition" shall mean an acquisition by (i) an employee benefit plan
          (or a trust forming a part thereof) maintained by (A) Medco Health or
          (B) any corporation or other Person of which a majority of its voting
          power or its voting equity securities or equity interest is owned,
          directly or indirectly, by Medco Health (for purposes of this
          definition, a "Related Entity"), (ii) Medco Health or any Related
          Entity, or (iii) any Person in connection with a "Non-Control
          Transaction" (as hereinafter defined); or

     (b)  The individuals who, immediately following the Spin-Off, are members
          of the Board of Directors of Medco Health (the "Incumbent Board"), (i)
          cease for any reason to constitute at least a majority of the members
          of the Board of Directors of Medco Health, or (ii) following a Merger
          (as hereinafter defined), do not constitute at least a majority of the
          board of directors of (x) the Surviving Corporation (as hereinafter
          defined), if fifty percent (50%) or more of the combined voting power
          of the then outstanding voting securities of the Surviving Corporation
          is not Beneficially Owned, directly or indirectly by a Parent
          Corporation, or (y) if there is one or more Parent Corporations, the
          ultimate Parent Corporation (as hereinafter defined); provided,
          however, that if the election, or nomination for election by the
          Company's common stockholders, of any new director was approved by a
          vote of at least a majority of the Incumbent Board, such new director
          shall, for purposes of this Plan, be considered as a member of the
          Incumbent Board; provided, further, however, that no individual shall
          be considered a member of the Incumbent Board if such individual
          initially assumed office as a result of an actual or threatened
          solicitation of proxies or consents by or on behalf of a Person other
          than the Board of Directors of Medco Health (a "Proxy Contest"),
          including by reason of any agreement intended to avoid or settle any
          Proxy Contest; or

     (c)  The consummation of:

                                       16

<PAGE>

                  (i) A merger, consolidation or reorganization with or into
         Medco Health or a direct or indirect subsidiary of Medco Health or in
         which securities of Medco Health are issued (a "Merger"), unless the
         Merger is a "Non-Control Transaction." A "Non-Control Transaction"
         shall mean:

                  (A) the stockholders of Medco Health immediately before such
         Merger own directly or indirectly immediately following the Merger at
         least fifty percent (50%) of the outstanding common stock and the
         combined voting power of the outstanding voting securities of (x) the
         corporation resulting from such Merger (the "Surviving Corporation"),
         if fifty percent (50%) or more of the combined voting power of the then
         outstanding voting securities of the Surviving Corporation is not
         Beneficially Owned, directly or indirectly by another corporation (a
         "Parent Corporation"), or (y) if there is one or more Parent
         Corporations, the ultimate Parent Corporation;

                  (B) the individuals who were members of the Incumbent Board
         immediately prior to the execution of the agreement providing for the
         Merger, constitute at least a majority of the members of the board of
         directors of, (x) the Surviving Corporation, if fifty percent (50%) or
         more of the combined voting power of the then outstanding voting
         securities of the Surviving Corporation is not Beneficially Owned,
         directly or indirectly by a Parent Corporation, or (y) if there is one
         or more Parent Corporations, the ultimate Parent Corporation; and

         (C) no Person other than (1) Medco Health or another corporation that
         is a party to the agreement of Merger, (2) any Related Entity, or (3)
         any employee benefit plan (or any trust forming a part thereof) that,
         immediately prior to the Merger, was maintained by Medco Health or any
         Related Entity, or (4) any Person who, immediately prior to the Merger
         had Beneficial Ownership of twenty percent (20%) or more of the then
         outstanding shares of Common Stock or Voting Securities, has Beneficial
         Ownership, directly or indirectly, of twenty percent (20%) or more of
         the combined voting power of the outstanding voting securities or
         common stock of (x) the Surviving Corporation, if fifty percent (50%)
         or more of the combined voting power of the then outstanding voting
         securities of the Surviving Corporation is not Beneficially Owned,
         directly or indirectly by a Parent Corporation, or (y) if there is one
         or more Parent Corporations, the ultimate Parent Corporation.

         (ii) A complete liquidation or dissolution of Medco Health; or

         (iii) The sale or other disposition of all or substantially all of the
         assets of Medco Health and its subsidiaries taken as a whole to any
         Person (other than a transfer to a Related Entity or under conditions
         that would constitute a Non-Control Transaction with the disposition of
         assets being regarded as a Merger for this purpose or the distribution
         to Medco Health's stockholders of the stock of a Related Entity or any
         other assets).

                                       17

<PAGE>

     Notwithstanding the foregoing, a Change in Control shall not be deemed to
occur solely because any Person (the "Subject Person") acquired Beneficial
Ownership of more than the permitted amount of the then outstanding shares of
Common Stock or Voting Securities as a result of the acquisition of shares of
Common Stock or Voting Securities by Medco Health which, by reducing the number
of shares of Common Stock or Voting Securities then outstanding, increases the
proportional number of shares Beneficially Owned by the Subject Persons;
provided, that if a Change in Control would occur (but for the operation of this
sentence) as a result of the acquisition of shares of Common Stock or Voting
Securities by Medco Health, and after such share acquisition by Medco Health,
the Subject Person becomes the Beneficial Owner of any additional shares of
Common Stock or Voting Securities which increases the percentage of the then
outstanding shares of Common Stock or Voting Securities Beneficially Owned by
the Subject Person, then a Change in Control shall occur.

         Notwithstanding the foregoing, there shall not be a Change in Control
if, in advance of such event, the Executive agrees in writing that such event
shall not constitute a Change in Control.

                                       18

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