Exhibit 10.8

AMENDMENT ONE

to the

MERCK & CO., INC.

2004 INCENTIVE STOCK PLAN

(Amended and Restated as of December 19, 2006)

WHEREAS, pursuant to and upon consummation of the Agreement and Plan of Merger,
dated March 8, 2009, as amended, by and among Merck & Co., Inc. (“Merck”),
Schering-Plough Corporation, SP Merger Subsidiary One, Inc., and SP Merger
Subsidiary Two, Inc. (the “Transactions”), Schering-Plough Corporation will
change its name to Merck & Co. Inc., (“Parent”) and Merck will change its name
to Merck Sharp & Dohme Corp. (“MSD”), and will become a wholly-owned subsidiary
of Parent;

WHEREAS, under Section 13 of the Merck & Co., Inc. 2004 Incentive Stock Plan
(the “2004 ISP”), the Board of Directors of Merck may from time to time amend
the terms of the 2004 ISP and desires to amend, contingent on and effective upon
the consummation of the Transactions, the 2004 ISP to update the plan name and
to reflect, (i) the change to the stock underlying any equity awards granted
under the 2004 ISP that remain outstanding as of the closing date of the
Transactions from common stock of Merck, par value $0.01 per share, to common
stock of Parent, par value $0.50 per share; and (ii) other technical changes
that are considered necessary for the proper continuation of such outstanding
equity grants and the 2004 ISP in light of the Transactions; provided however,
for the avoidance of any doubt, if the Transactions is not consummated, all
amendments as set forth herein shall be null and void;

NOW, THEREFORE, BE IT

RESOLVED, that in consideration of the premises, the 2004 ISP is hereby amended
contingent on and as of the consummation of the Transactions as follows:

1. The official name of the 2004 ISP shall be the Merck Sharp & Dohme Corp. 2004
Incentive Stock Plan.

2. The first sentence of Section 1 of the 2004 ISP shall be deleted and replaced
with the following four sentences:

The 2004 Incentive Stock Plan (the “Plan”), effective May 1, 2003, amended and
restated December 19, 2006 was established to encourage employees of Merck &
Co., Inc. its subsidiaries, its affiliates and its joint ventures to acquire
shares of Merck & Co., Inc. The Plan is further amended, effective as of Closing
Date (“Closing Date”), as such term is defined in Section 1.2 of the Agreement
and Plan of Merger dated as of March 8, 2009, by and among Merck & Co., Inc.,
Schering Plough Corporation, SP Merger Subsidiary One, Inc., and SP Merger
Subsidiary Two, Inc. (the “Transactions”), whereby Schering Plough Corporation
will be renamed Merck & Co. Inc. (“Parent”) and the entity known

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immediately before the Closing Date as Merck & Co., Inc. will be renamed Merck
Sharp and Dohme Corp. (“MSD or Company”) and will be a wholly-owned subsidiary
of Parent. The Plan, as amended and restated as of the Closing Date, will
provide with respect to all Incentives, as defined in the Plan, granted prior to
and which remained outstanding on the Closing Date, for the Incentive to be
settled in, or the holder thereof to receive upon exercise of such Incentive,
shares of common stock of Parent, par value $0.50 per share (“Parent Common
Stock”), in lieu of shares of MSD (formerly Merck & Co., Inc.). For all purposes
under the Plan, effective on the Closing Date, all references to “Common Stock”
in the Plan shall refer to “Parent Common Stock.”

3. The first two sentences of Section 2 of the 2004 ISP Plan shall be amended to
read in their entirety as follows:

The Plan shall be administered by the Compensation and Benefits Committee of the
Board of Directors of Parent (the “Committee”). A Director of Parent may serve
on the Committee if he or she (i) is a “Non-Employee Director” for purposes of
Rule 16b-3 under the Securities Exchange Act of 1934, as amended (the “Exchange
Act”) and (ii) satisfies the requirements of an “outside director” for purposes
of Section 162(m) of the Internal Revenue Code (the “Code”).

4. All references in the 2004 ISP to the “Board of Directors” or the “Board”
shall refer to the Board of Directors of Parent.

5. A new section 21(f) is added as follows:

Beginning on the Closing Date, for purposes of the Section 21 and the Schedule
entitled “Merck Change in Control” that follows this Section 21, with respect to
all awards granted pursuant to the Plan that remain outstanding as of the
consummation of the Transactions, the definition of a “Change in Control” that
applies to such awards shall be governed by Section 7.2(c) of Parent’s Change in
Control Separation Benefits Plan; provided, however, that as to any award under
the Plan that consists of deferred compensation subject to Section 409A of the
Code, the applicable definition of “Change in Control” shall be deemed modified
to the extent necessary to comply with Section 409A of the Code.

6. This amendment is effective as of the Closing Date of the Transactions.

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MERCK & CO., INC.

2004 INCENTIVE STOCK PLAN

(Amended and Restated as of December 19, 2006)

1. Purpose

The 2004 Incentive Stock Plan (the “Plan”), effective May 1, 2003, is
established to encourage employees of Merck & Co., Inc. (the “Company”), its
subsidiaries, its affiliates and its joint ventures to acquire Common Stock in
the Company (“Common Stock”). It is believed that the Plan will serve the
interests of the Company and its stockholders because it allows employees to
have a greater personal financial interest in the Company through ownership of,
or the right to acquire its Common Stock, which in turn will stimulate
employees’ efforts on the Company’s behalf, and maintain and strengthen their
desire to remain with the Company. It is believed that the Plan also will assist
in the recruitment of employees.

2. Administration

The Plan shall be administered by the Compensation and Benefits Committee of the
Board of Directors of the Company (the “Committee”). A Director of the Company
may serve on the Committee only if he or she (i) is a “Non-Employee Director”
for purposes of Rule 16b-3 under the Securities Exchange Act of 1934, as amended
(the “Exchange Act”), and (ii) satisfies the requirements of an “outside
director” for purposes of Section 162(m) of the Internal Revenue Code (the
“Code”). The Committee shall be responsible for the administration of the Plan
including, without limitation, determining which Eligible Employees receive
Incentives, the types of Incentives they receive under the Plan, the number of
shares covered by Incentives granted under the Plan, and the other terms and
conditions of such Incentives. Determinations by the Committee under the Plan
including, without limitation, determinations of the Eligible Employees, the
form, amount and timing of Incentives, the terms and provisions of Incentives
and the writings evidencing Incentives, need not be uniform and may be made
selectively among Eligible Employees who receive, or are eligible to receive,
Incentives hereunder, whether or not such Eligible Employees are similarly
situated.

The Committee shall have the responsibility of construing and interpreting the
Plan, including the right to construe disputed or doubtful Plan provisions, and
of establishing, amending and construing such rules and regulations as it may
deem necessary or desirable for the proper administration of the Plan. Any
decision or action taken or to be taken by the Committee, arising out of or in
connection with the construction, administration, interpretation and effect of
the Plan and of its rules and regulations, shall, to the maximum extent
permitted by applicable law, be within its absolute discretion (except as
otherwise specifically provided herein) and shall be final, binding and
conclusive upon the Company, all Eligible Employees and any person claiming
under or through any Eligible Employee.

The Committee, as permitted by applicable state law, may delegate any or all of
its power and authority hereunder to the Chief Executive Officer or such other
senior member of management as the Committee deems appropriate; provided,
however, that the Committee may not delegate its authority with regard to any
matter or action affecting an officer subject to Section 16 of the Exchange Act
and that no such delegation shall be made in the case of Incentives intended to
be qualified under Section 162(m) of the Code.

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For the purpose of this section and all subsequent sections, the Plan shall be
deemed to include this Plan and any comparable sub-plans established by
subsidiaries which, in the aggregate, shall constitute one Plan governed by the
terms set forth herein.

3. Eligibility

(a) Employees. Regular full-time and part-time employees employed by the
Company, its parent, if any, or its subsidiaries, its affiliates and its joint
ventures, including officers, whether or not directors of the Company, and
employees of a joint venture partner or affiliate of the Company who provide
services to the joint venture with such partner or affiliate (each such person,
an “Employee”), shall be eligible to participate in the Plan if designated by
the Committee (“Eligible Employees”).

(b) Non-employees. The term “Employee” shall not include any of the following
(collectively, “Excluded Persons”): a director who is not an employee or an
officer; a person who is an independent contractor, or agrees or has agreed that
he/she is an independent contractor; a person who has any agreement or
understanding with the Company, or any of its affiliates or joint venture
partners that he/she is not an employee or an Eligible Employee, even if he/she
previously had been an employee or Eligible Employee; a person who is employed
by a temporary or other employment agency, regardless of the amount of control,
supervision or training provided by the Company or its affiliates; or a “leased
employee” as defined under Section 414 (n) of the Code. An Excluded Person is
not an Eligible Employee and cannot receive Incentives even if a court, agency
or other authority rules that he/she is a common-law employee of the Company or
its affiliates.

(c) No Right To Continued Employment. Nothing in the Plan shall interfere with
or limit in any way the right of the Company, its parent, its subsidiaries, its
affiliates or its joint ventures to terminate the employment of any participant
at any time, nor confer upon any participant the right to continue in the employ
of the Company, its parent, its subsidiaries, its affiliates or its joint
ventures. No Eligible Employee shall have a right to receive an Incentive or any
other benefit under this Plan or having been granted an Incentive or other
benefit, to receive any additional Incentive or other benefit. Neither the award
of an Incentive nor any benefits arising under such Incentives shall constitute
an employment contract with the Company, its parent, its subsidiaries, its
affiliates or its joint ventures, and, accordingly, this Plan and the benefits
hereunder may be terminated at any time in the sole and exclusive discretion of
the Company without giving rise to liability on the part of the Company, its
parent, its subsidiaries, its affiliates or its joint ventures for severance.
Except as may be otherwise specifically stated in any other employee benefit
plan, policy or program, neither any Incentive under this Plan nor any amount
realized from any such Incentive shall be treated as compensation for any
purposes of calculating an employee’s benefit under any such plan, policy or
program.

4. Term of the Plan

This Plan shall be effective as of May 1, 2003, subject to the approval of the
Plan by the affirmative vote of the stockholders of the Company entitled to vote
thereon at the time of such approval. No Incentive shall be granted under the
Plan after April 30, 2013, but the term and exercise of Incentives granted
theretofore may extend beyond that date.

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5. Incentives

Incentives under the Plan may be granted in any one or a combination of
(a) Incentive Stock Options, (b) Nonqualified Stock Options, (c) Stock
Appreciation Rights, (d) Restricted Stock Grants, (e) Performance Shares,
(f) Share Awards and (g) Phantom Stock Awards (collectively “Incentives”). All
Incentives shall be subject to the terms and conditions set forth herein and to
such other terms and conditions as may be established by the Committee.

6. Shares Available for Incentives

(a) Shares Available. Subject to the provisions of Section 6(c), the maximum
number of shares of Common Stock of the Company that may be issued under the
Plan is 115 million. Any shares under this Plan or under the predecessor
Incentive Stock Plans that are not purchased or awarded under an Incentive that
has lapsed, expired, terminated or been cancelled, may be used for the further
grant of Incentives under the Plan. Incentives and similar awards issued by an
entity that is merged into or with the Company, acquired by the Company or
otherwise involved in a similar corporate transaction with the Company are not
considered issued under this Plan. Shares under this Plan may be delivered by
the Company from its authorized but unissued shares of Common Stock or from
issued and reacquired Common Stock held as treasury stock, or both. In no event
shall fractional shares of Common Stock be issued under the Plan.

(b) Limit on an Individual’s Incentives. In any calendar year, no Eligible
Employee may receive (i) Incentives covering more than 3 million shares of the
Company’s Common Stock (such number of shares shall be adjusted in accordance
with Section 6(c)), or (ii) any Incentive if such person owns more than 10
percent of the stock of the Company within the meaning of Section 422 of the
Code, or (iii) any Incentive Stock Option, as defined in Section 422 of the
Code, that would result in such person receiving a grant of Incentive Stock
Options for stock that would have an aggregate fair market value in excess of
$100,000, determined as of the time that the Incentive Stock Option is granted,
that would be exercisable for the first time by such person during any calendar
year.

(c) Adjustment of Shares. In the event of a reorganization, recapitalization,
stock split, stock dividend, extraordinary cash dividend, combination of shares,
merger, consolidation, rights offering, spin off, split off, split up or other
similar change in the capital structure of the Company, the Committee shall make
equitable adjustments to (i) the number and kind of shares authorized for
issuance under the Plan, (ii) the number and kind of shares subject to
outstanding Incentives, (iii) the option price of Stock Options and (iv) the
grant value of Stock Appreciation Rights. Any such determination shall be final,
binding and conclusive on all parties.

7. Stock Options

The Committee may grant options qualifying as Incentive Stock Options as defined
in Section 422 of the Code, and options other than Incentive Stock Options
(“Nonqualified Options”) (collectively “Stock Options”). Such Stock Options
shall be subject to the following terms and conditions and such other terms and
conditions as the Committee may prescribe:

(a) Stock Option Price. The option price per share with respect to each Stock
Option shall be determined by the Committee, but shall not be less than 100
percent of the fair market value of the Common Stock on the date the Stock
Option is granted, as determined by the Committee.

(b) Period of Stock Option. The period of each Stock Option shall be fixed by
the Committee, provided that the period for all Stock Options shall not exceed
ten years from the

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grant; provided further, however, that, in the event of the death of an Optionee
prior to the expiration of a Nonqualified Option, such Nonqualified Option may,
if the Committee so determines, be exercisable for up to eleven years from the
date of the grant. The Committee may, subsequent to the granting of any Stock
Option, extend the term thereof, but in no event shall the extended term exceed
ten years from the original grant date.

(c) Exercise of Stock Option and Payment Therefore. No shares shall be issued
until full payment of the option price has been made. The option price may be
paid in cash or, if the Committee determines, in shares of Common Stock or a
combination of cash and shares of Common Stock. If the Committee approves the
use of shares of Common Stock as a payment method, the Committee shall establish
such conditions as it deems appropriate for the use of Common Stock to exercise
a Stock Option. Stock Options awarded under the Plan shall be exercised through
such procedure or program as the Committee may establish or define from time to
time, which may include a designated broker that must be used in exercising such
Stock Options. The Committee may establish rules and procedures to permit an
optionholder to defer recognition of gain upon the exercise of a Stock Option.

(d) First Exercisable Date. The Committee shall determine how and when shares
covered by a Stock Option may be purchased. The Committee may establish waiting
periods, the dates on which Stock Options become exercisable or “vested” and,
subject to paragraph (b) of this section, exercise periods. The Committee may
accelerate the exercisability of any Stock Option or portion thereof.

(e) Termination of Employment. Unless determined otherwise by the Committee,
upon the termination of a Stock Option grantee’s employment (for any reason
other than gross misconduct), Stock Option privileges shall be limited to the
shares that were immediately exercisable at the date of such termination. The
Committee, however, in its discretion, may provide that any Stock Options
outstanding but not yet exercisable upon the termination of a Stock Option
grantee’s employment may become exercisable in accordance with a schedule
determined by the Committee. Such Stock Option privileges shall expire unless
exercised within such period of time after the date of termination of employment
as may be established by the Committee, but in no event later than the
expiration date of the Stock Option.

(f) Termination Due to Misconduct. If a Stock Option grantee’s employment is
terminated for gross misconduct, as determined by the Company, all rights under
the Stock Option shall expire upon the date of such termination.

(g) Limits on Incentive Stock Options. Except as may otherwise be permitted by
the Code, an Eligible Employee may not receive a grant of Incentive Stock
Options for stock that would have an aggregate fair market value in excess of
$100,000 (or such other amount as the Internal Revenue Service may decide from
time to time), determined as of the time that the Incentive Stock Option is
granted, that would be exercisable for the first time by such person during any
calendar year.

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8. Stock Appreciation Rights

The Committee may, in its discretion, grant a right to receive the appreciation
in the fair market value of shares of Common Stock (“Stock Appreciation Right”)
either singly or in combination with an underlying Stock Option granted
hereunder. Such Stock Appreciation Right shall be subject to the following terms
and conditions and such other terms and conditions as the Committee may
prescribe:

(a) Time and Period of Grant. If a Stock Appreciation Right is granted with
respect to an underlying Stock Option, it may be granted at the time of the
Stock Option grant or at any time thereafter but prior to the expiration of the
Stock Option grant. If a Stock Appreciation Right is granted with respect to an
underlying Stock Option, at the time the Stock Appreciation Right is granted the
Committee may limit the exercise period for such Stock Appreciation Right,
before and after which period no Stock Appreciation Right shall attach to the
underlying Stock Option. In no event shall the exercise period for a Stock
Appreciation Right granted with respect to an underlying Stock Option exceed the
exercise period for such Stock Option. If a Stock Appreciation Right is granted
without an underlying Stock Option, the period for exercise of the Stock
Appreciation Right shall be set by the Committee.

(b) Value of Stock Appreciation Right. If a Stock Appreciation Right is granted
with respect to an underlying Stock Option, the grantee will be entitled to
surrender the Stock Option which is then exercisable and receive in exchange
therefor an amount equal to the excess of the fair market value of the Common
Stock on the date the election to surrender is received by the Company in
accordance with exercise procedures established by the Company over the Stock
Option price (the “Spread”) multiplied by the number of shares covered by the
Stock Option which is surrendered. If a Stock Appreciation Right is granted
without an underlying Stock Option, the grantee will receive upon exercise of
the Stock Appreciation Right an amount equal to the excess of the fair market
value of the Common Stock on the date the election to surrender such Stock
Appreciation Right is received by the Company in accordance with exercise
procedures established by the Company over the fair market value of the Common
Stock on the date of grant multiplied by the number of shares covered by the
grant of the Stock Appreciation Right. Notwithstanding the foregoing, in its
sole discretion the Committee at the time it grants a Stock Appreciation Right
may provide that the Spread covered by such Stock Appreciation Right may not
exceed a specified amount.

(c) Payment of Stock Appreciation Right. Payment of a Stock Appreciation Right
shall be in the form of shares of Common Stock, cash or any combination of
shares and cash. The form of payment upon exercise of such a right shall be
determined by the Committee either at the time of grant of the Stock
Appreciation Right or at the time of exercise of the Stock Appreciation Right.

9. Performance Share Awards

The Committee may grant awards under which payment may be made in shares of
Common Stock, cash or any combination of shares and cash if the performance of
the Company or its parent or any subsidiary, division, affiliate or joint
venture of the Company selected by the Committee during the Award Period meets
certain goals established by the Committee (“Performance Share Awards”). Such
Performance Share Awards shall be subject to the following terms and conditions
and such other terms and conditions as the Committee may prescribe:

(a) Award Period and Performance Goals. The Committee shall determine and
include in a Performance Share Award grant the period of time for which a
Performance Share Award is made (“Award Period”). The Committee also shall
establish performance objectives (“Performance Goals”) to be met by the Company,
its parent, subsidiary, division, affiliate or joint venture of the Company
during the Award Period as a condition to payment of the Performance Share
Award. The Performance Goals may include share price, pre-tax profits,

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earnings per share, return on stockholders’ equity, return on assets, sales, net
income or any combination of the foregoing or, solely for an Award not intended
to constitute “performance-based compensation” under Section 162(m) of the Code,
any other financial or other measurement established by the Committee. The
Performance Goals may include minimum and optimum objectives or a single set of
objectives.

(b) Payment of Performance Share Awards. The Committee shall establish the
method of calculating the amount of payment to be made under a Performance Share
Award if the Performance Goals are met, including the fixing of a maximum
payment. The Performance Share Award shall be expressed in terms of shares of
Common Stock and referred to as “Performance Shares”. After the completion of an
Award Period, the performance of the Company, its parent, subsidiary, division,
affiliate or joint venture of the Company shall be measured against the
Performance Goals, and the Committee shall determine, in accordance with the
terms of such Performance Share Award, whether all, none or any portion of a
Performance Share Award shall be paid. The Committee, in its discretion, may
elect to make payment in shares of Common Stock, cash or a combination of shares
and cash. Any cash payment shall be based on the fair market value of
Performance Shares on or as soon as practicable prior to, the date of payment.
The Committee may establish rules and procedures to permit a grantee to defer
recognition of income upon the attainment of a Performance Share Award.

(c) Revision of Performance Goals. As to any Award not intended to constitute
“performance-based compensation” under Section 162(m) of the Code, at any time
prior to the end of an Award Period, the Committee may revise the Performance
Goals and the computation of payment if unforeseen events occur which have a
substantial effect on the performance of the Company, its parent, subsidiary,
division, affiliate or joint venture of the Company and which, in the judgment
of the Committee, make the application of the Performance Goals unfair unless a
revision is made.

(d) Requirement of Employment. A grantee of a Performance Share Award must
remain in the employ of the Company, its parent, subsidiary, affiliate or joint
venture until the completion of the Award Period in order to be entitled to
payment under the Performance Share Award; provided that the Committee may, in
its discretion, provide for a full or partial payment where such an exception is
deemed equitable.

(e) Dividends. The Committee may, in its discretion, at the time of the granting
of a Performance Share Award, provide that any dividends declared on the Common
Stock during the Award Period, and which would have been paid with respect to
Performance Shares had they been owned by a grantee, be (i) paid to the grantee,
or (ii) accumulated for the benefit of the grantee and used to increase the
number of Performance Shares of the grantee.

(f) Limit on Performance Share Awards. Incentives granted as Performance Share
Awards under this section, Restricted Stock Grants under Section 10 and Other
Share Based Awards under Section 11 shall not exceed, in the aggregate,
12 million shares of Common Stock (such number of shares shall be adjusted in
accordance with Section 6(c)).

10. Restricted Stock Grants

The Committee may award shares of Common Stock to an Eligible Employee, which
shares shall be subject to the following terms and conditions and such other
terms and conditions as the Committee may prescribe (“Restricted Stock Grant”):

(a) Requirement of Employment. A grantee of a Restricted Stock Grant must remain
in the

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employment of the Company during a period designated by the Committee
(“Restriction Period”) in order to retain the shares under the Restricted Stock
Grant. If the grantee leaves the employment of the Company prior to the end of
the Restriction Period, the Restricted Stock Grant shall terminate and the
shares of Common Stock shall be returned immediately to the Company provided
that the Committee may, at the time of the grant, provide for the employment
restriction to lapse with respect to a portion or portions of the Restricted
Stock Grant at different times during the Restriction Period. The Committee may,
in its discretion, also provide for such complete or partial exceptions to the
employment restriction as it deems equitable.

(b) Restrictions on Transfer and Legend on Stock Certificates. During the
Restriction Period, the grantee may not sell, assign, transfer, pledge or
otherwise dispose of the shares of Common Stock. Each certificate for shares of
Common Stock issued hereunder shall contain a legend giving appropriate notice
of the restrictions in the grant.

(c) Escrow Agreement. The Committee may require the grantee to enter into an
escrow agreement providing that the certificates representing the Restricted
Stock Grant will remain in the physical custody of an escrow holder until all
restrictions are removed or expire.

(d) Lapse of Restrictions. All restrictions imposed under the Restricted Stock
Grant shall lapse upon the expiration of the Restriction Period if the
conditions as to employment set forth above have been met. The grantee shall
then be entitled to have the legend removed from the certificates. The Committee
may establish rules and procedures to permit a grantee to defer recognition of
income upon the expiration of the Restriction Period.

(e) Dividends. The Committee shall, in its discretion, at the time of the
Restricted Stock Grant, provide that any dividends declared on the Common Stock
during the Restriction Period shall either be (i) paid to the grantee, or
(ii) accumulated for the benefit of the grantee and paid to the grantee only
after the expiration of the Restriction Period.

(f) Performance Goals. The Committee may designate whether any Restricted Stock
Grant is intended to be “performance-based compensation” as that term is used in
Section 162(m) of the Code. Any such Restricted Stock Grant designated to be
“performance-based compensation” shall be conditioned on the achievement of one
or more Performance Goals (as defined in Section 9(a)), to the extent required
by Section 162(m).

(g) Limit on Restricted Stock Grant. Incentives granted as Restricted Stock
Grants under this section, Performance Share Awards under Section 9 and Other
Share Based Awards under Section 11 shall not exceed, in the aggregate,
12 million shares of Common Stock (such number of shares shall be adjusted in
accordance with Section 6(c)).

11. Other Share-Based Awards

The Committee may grant an award of shares of common stock (a “Share Award”) to
any Eligible Employee on such terms and conditions as the Committee may
determine in its sole discretion. Share Awards may be made as additional
compensation for services rendered by the Eligible Employee or may be in lieu of
cash or other compensation to which the Eligible Employee is entitled from the
Company. Incentives granted as Share Based Awards under this section,
Performance Share Awards under Section 9 and Restricted Stock Grants under
Section 10 shall not exceed, in the aggregate, 12 million shares of Common Stock
(such number of shares shall be adjusted in accordance with Section 6(c)).

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12. Transferability

Each Incentive Stock Option granted under the Plan shall not be transferable
other than by will or the laws of descent and distribution; each other Incentive
granted under the Plan will not be transferable or assignable by the recipient,
and may not be made subject to execution, attachment or similar procedures,
other than by will or the laws of descent and distribution or as determined by
the Committee in accordance with regulations promulgated under the Securities
Exchange Act of 1934, or any other applicable law or regulation. Notwithstanding
the foregoing, the Committee, in its discretion, may adopt rules permitting the
transfer, solely as gifts during the grantee’s lifetime, of Stock Options (other
than Incentive Stock Options) to members of a grantee’s immediate family or to
trusts, family partnerships or similar entities for the benefit of such
immediate family members. For this purpose, immediate family member means the
grantee’s spouse, parent, child, stepchild, grandchild and the spouses of such
family members. The terms of a Stock Option shall be final, binding and
conclusive upon the beneficiaries, executors, administrators, heirs and
successors of the grantee.

13. Discontinuance or Amendment of the Plan

The Board of Directors may discontinue the Plan at any time and may from time to
time amend or revise the terms of the Plan as permitted by applicable statutes,
except that it may not, without the consent of the grantees affected, revoke or
alter, in a manner unfavorable to the grantees of any Incentives hereunder, any
Incentives then outstanding, nor may the Board amend the Plan without
stockholder approval where the absence of such approval would cause the Plan to
fail to comply with Rule 16b-3 under the Exchange Act, or any other requirement
of applicable law or regulation. Unless approved by the Company’s stockholders
or as otherwise specifically provided under this Plan, no adjustments or
reduction of the exercise price of any outstanding Incentives shall be made in
the event of a decline in stock price, either by reducing the exercise price of
outstanding Incentives or through cancellation of outstanding Incentives in
connection with regranting of Incentives at a lower price to the same
individual.

14. No Limitation on Compensation

Nothing in the Plan shall be construed to limit the right of the Company to
establish other plans or to pay compensation to its employees, in cash or
property, in a manner which is not expressly authorized under the Plan.

15. No Constraint on Corporate Action

Nothing in the Plan shall be construed (i) to limit, impair or otherwise affect
the Company’s right or power to make adjustments, reclassifications,
reorganizations or changes of its capital or business structure, or to merge or
consolidate, or dissolve, liquidate, sell or transfer all or any part of its
business or assets, or (ii) except as provided in Section 13, to limit the right
or power of the Company, its parent, or any subsidiary, affiliate or joint
venture to take any action which such entity deems to be necessary or
appropriate.

16. Withholding Taxes

The Company shall be entitled to deduct from any payment under the Plan,
regardless of the form of such payment, the amount of all applicable income and
employment taxes required by law to be withheld with respect to such payment or
may require the Eligible Employee to pay to it such tax prior to and as a
condition of the making of such payment. In accordance with any

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applicable administrative guidelines it establishes, the Committee may allow an
Eligible Employee to pay the amount of taxes required by law to be withheld from
an Incentive by withholding from any payment of Common Stock due as a result of
such Incentive, or by permitting the Eligible Employee to deliver to the
Company, shares of Common Stock having a fair market value, as determined by the
Committee, equal to the amount of such required withholding taxes.

17. Compliance with Section 16

With respect to Eligible Employees subject to Section 16 of the Exchange Act
(“Section 16 Officers”), transactions under the Plan are intended to comply with
all applicable conditions of Rule 16b-3 or its successor under the Exchange Act.
To the extent that compliance with any Plan provision applicable solely to the
Section 16 Officers is not required in order to bring a transaction by such
Section 16 Officer into compliance with Rule 16b-3, it shall be deemed null and
void as to such transaction, to the extent permitted by law and deemed advisable
by the Committee and its delegees. To the extent any provision of the Plan or
action by the Plan administrators involving such Section 16 Officers is deemed
not to comply with an applicable condition of Rule 16b-3, it shall be deemed
null and void as to such Section 16 Officers, to the extent permitted by law and
deemed advisable by the Plan administrators.

18. Use of Proceeds

The proceeds received by the Company from the sale of stock under the Plan shall
be added to the general funds of the Company and shall be used for such
corporate purposes as the Board of Directors shall direct.

19. Governing Law

The Plan, and all agreements hereunder, shall be construed in accordance with
and governed by the laws of the State of New Jersey without giving effect to the
principles of conflicts of laws.

20. Offset and Suspension of Exercise

Anything to the contrary in the Plan notwithstanding, the Plan administrators
may (i) offset any Incentive by amounts reasonably believed to be owed to the
Company by the grantee and (ii) disallow an Incentive to be exercised or
otherwise payable during a time when the Company is investigating reasonably
reliable allegations of gross misconduct by the grantee.

21. Effect of a Change in Control

(a) Options.

1. Vesting of Options Other Than Key R&D Options. Upon the occurrence of a
Change in Control, each Stock Option which is outstanding immediately prior to
the Change in Control, other than the Key R&D Options, shall immediately become
fully vested and exercisable.

2. Vesting of Key R&D Options.

(i) Subject to Section 21(a)(2)(ii), upon the occurrence of a Change in Control,
each Key R&D Option shall continue to be subject to the performance-based
vesting schedule applicable thereto immediately prior to the Change in Control.

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(ii) Notwithstanding Section 21(a)(2)(i), if the Stock Options do not continue
to be outstanding following the Change in Control or are not exchanged for or
converted into options to purchase securities of a successor entity (“Successor
Options”), then, upon the occurrence of a Change in Control, all or a portion of
each Key R&D Option shall immediately vest and become exercisable in the
following percentages: (A) if such Key R&D Option’s first milestone has not been
reached before the date of the Change in Control, 14% of the then-unvested
portion of the KeyR&D Option shall vest and become exercisable and the remainder
shall be forfeited; (B) if only such Key R&D Option’s first milestone has been
reached before the date of the Change in Control, 42% of the then-unvested
portion of the Key R&D Option shall vest and become exercisable and the
remainder shall be forfeited; and (C) if such Key R&D Option’s first and second
milestones have been reached before the date of the Change in Control, 100% of
the then-unvested portion of the Key R&D Option shall vest and become
exercisable.

3. Post-Termination Exercise Period. If Stock Options continue to be outstanding
following the Change in Control or are exchanged for or converted into Successor
Options, then the portion of such Stock Options or such Successor Options, as
applicable, that is vested and exercisable immediately following the termination
of employment of the holder thereof after the Change in Control shall remain
exercisable following such termination for five years from the date of such
termination (but not beyond the remainder of the term thereof) provided,
however, that, if such termination is by reason of gross misconduct, death or
retirement (as these terms are applied to awards granted under the Plan), then
those provisions of the Plan that are applicable to a termination by reason of
gross misconduct, death or retirement shall apply to such termination.

4. Cashout of Stock Options. If the Stock Options do not continue to be
outstanding following the Change in Control and are not exchanged for or
converted into Successor Options, each holder of a vested and exercisable option
shall be entitled to receive, as soon as practicable following the Change in
Control, for each share of Common Stock subject to a vested and exercisable
option, an amount of cash determined by the Committee prior to the Change in
Control but in no event less than the excess of the Change in Control Price over
the exercise price thereof (subject to any existing deferral elections then in
effect). If the consideration to be paid in a Change in Control is not entirely
shares of common stock of an acquiring or resulting corporation, then the
Committee may, prior to the Change in Control, provide for the cancellation of
outstanding Stock Options at the time of the Change in Control in whole or in
part for cash pursuant to this Section 21(a)(4) or may provide for the exchange
or conversion of outstanding Stock Options at the time of the Change in Control
in whole or in part, and, in connection with any such provision, may (but shall
not be obligated to) permit holders of Stock Options to make such elections
related thereto as it determines are appropriate.

(b) Restricted Stock Units and Performance Share Units.

1. Vesting of Restricted Stock Units. Upon the occurrence of a Change in
Control, each unvested restricted stock unit award which is outstanding
immediately prior to the Change in Control under the Plan shall immediately
become fully vested.

2. Vesting of Performance Share Units. Upon the occurrence of a Change in
Control, each unvested performance share unit award which is outstanding
immediately prior to the Change in Control under the Plan shall immediately
become vested in an amount equal to the PSU Pro Rata Amount.

3. Settlement of Restricted Stock Units and Performance Share Units.

(i) If the Common Stock continues to be widely held and freely tradable
following the Change in

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Control or is exchanged for or converted into securities of a successor entity
that are widely held and freely tradable, then the restricted stock units and
the vested performance share units shall be paid in shares of Common Stock or
such other securities as soon as practicable after the date of the Change in
Control (subject to any existing deferral elections then in effect).

(ii) If the Common Stock does not continue to be widely held and freely tradable
following the Change in Control and is not exchanged for or converted into
securities of a successor entity that are widely held and freely tradable, then
the restricted stock units and the vested performance share units shall be paid
in cash as soon as practicable after the date of the Change in Control (subject
to any existing deferral elections then in effect).

(c) Other Provisions.

1. Except to the extent required by applicable law, for the entirety of the
Protection Period, the material terms of the Plan shall not be modified in any
manner that is materially adverse to the Qualifying Participants (it being
understood that this Section 21(c) shall not require that any specific type or
levels of equity awards be granted to Qualifying Participants following the
Change in Control).

2. During the Protection Period, the Plan may not be amended or modified to
reduce or eliminate the protections set forth in Section 21(c)(1) and may not be
terminated.

3. The Company shall pay all legal fees and related expenses (including the
costs of experts, evidence and counsel) reasonably and in good faith incurred by
a Qualifying Participant if the Qualifying Participant prevails on his or her
claim for relief in an action (x) by the Qualifying Participant claiming that
the provisions of Section 21(c)(1) or 21(c)(2) of the Plan have been violated
(but, for avoidance of doubt, excluding claims for plan benefits in the ordinary
course) and (y) if applicable, by the Company or the Qualifying Participant’s
employer to enforce post-termination covenants against the Qualifying
Participant.

(d) Definitions. For purposes of this Section 21, the following terms shall have
the following meanings:

1. “Change in Control” shall have the meaning set forth in the Company’s Change
in Control Separation Benefits Plan; provided, however, that, as to any award
under the Plan that consists of deferred compensation subject to Section 409A of
the Code, the definition of “Change in Control” shall be deemed modified to the
extent necessary to comply with Section 409A of the Code.

2. “Change in Control Price” shall mean, with respect to a share of Common
Stock, the higher of (A) the highest reported sales price, regular way, of such
share in any transaction reported on the New York Stock Exchange Composite Tape
or other national exchange on which such shares are listed or on the Nasdaq
National Market during the ten-day period prior to and including the date of a
Change in Control and (B) if the Change in Control is the result of a tender or
exchange offer, merger, or other, similar corporate transaction, the highest
price per such share paid in such tender or exchange offer, merger or other,
similar corporate transaction; provided that, to the extent all or part of the
consideration paid in any such transaction consists of securities or other
noncash consideration, the value of such securities or other noncash
consideration shall be determined by the Committee.

3. “Key R&D Options” shall mean those performance-based options granted to
employees under the Key Research and Development Program described in the
applicable Schedule to the Rules and Regulations for the Plan.

4. “Protection Period” shall mean the period beginning on the date of the Change
in Control and ending on the second anniversary of the date of the Change in
Control.

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5. “PSU Pro Rata Amount” shall mean for each Performance Share Unit award, the
amount determined by multiplying (x) and (y), where (x) is the number of Target
Shares subject to the Performance Share Unit award times the Assumed Performance
Percentage and (y) is a fraction, the numerator of which is the number of whole
and partial calendar months elapsed during the applicable performance period
(counting any partial month as a whole month for this purpose) and the
denominator of which is the total number of months in the applicable performance
period. The Assumed Performance Percentage shall be determined by (1) averaging
the ranks during the Award Period as follows: (A) as to any completed
performance year as of the Change in Control, the actual rank (except that, if
fewer than 90 days have elapsed since the completion of such performance year,
the Target Rank shall be used), and (B) as to any performance year that is
incomplete or has not yet begun as of the Change in Control, the Target Rank,
(2) rounding the average rank calculated pursuant to the foregoing clause (1) to
the nearest whole number using ordinary numerical rounding, and (3) using the
Final Award Percentage associated with the number determined in the foregoing
clause (2). The Target Rank is the rank associated with 100% on the chart of
Final Award Percentages.

6. “Qualifying Participants” shall mean those individuals who participate in the
Plan (whether as current or former employees) as of immediately prior to the
Change in Control.

(e) Application. This Section 21 shall apply to Stock Options, restricted stock
unit awards and performance share unit awards granted after November 23, 2004.
(NOTE: For incentives granted before November 23, 2004, see Merck Change in
Control schedule.)

Merck Change in Control

(a) Options.

1. Vesting of Options Other Than Key R&D Options. Upon the occurrence of a
Change in Control, each Stock Option which is outstanding immediately prior to
the Change in Control, other than the Key R&D Options, shall immediately become
fully vested and exercisable.

2. Vesting of Key R&D Options.

(i) Subject to (a)(2)(ii) of this Schedule, upon the occurrence of a Change in
Control, each Key R&D Option shall continue to be subject to the
performance-based vesting schedule applicable thereto immediately prior to the
Change in Control.

(ii) Notwithstanding (a)(2)(i) of this Schedule, if the Stock Options do not
continue to be outstanding following the Change in Control or are not exchanged
for or converted into options to purchase securities of a successor entity
(“Successor Options”), then, upon the occurrence of a Change in Control, all or
a portion of each Key R&D Option shall immediately vest and become exercisable
in the following percentages: (A) if such Key R&D Option’s first milestone has
not been reached before the date of the Change in Control, 14% of the
then-unvested portion of the Key R&D Option shall vest and become exercisable
and the remainder shall be forfeited; (B) if only such Key R&D Option’s first
milestone has been reached before the date of the Change in Control, 42% of the
then-unvested portion of the Key R&D Option shall vest and become exercisable
and the remainder shall be forfeited; and (C) if such Key R&D Option’s first and
second milestones have been reached before the date of the Change in Control,
100% of the then- unvested portion of the Key R&D Option shall vest and become
exercisable.

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3. Post-Termination Exercise Period. If Stock Options continue to be outstanding
following the Change in Control or are exchanged for or converted into Successor
Options, then the portion of such Stock Options or such Successor Options, as
applicable, that is vested and exercisable immediately following the termination
of employment of the holder thereof after the Change in Control shall remain
exercisable following such termination for five years from the date of such
termination (but not beyond the remainder of the term thereof) provided,
however, that, if such termination is by reason of gross misconduct, death or
retirement (as these terms are applied to awards granted under the Plans), then
those provisions of the Plan that are applicable to a termination by reason of
gross misconduct, death or retirement, if any, shall apply to such termination.
If the effect of vesting pursuant to this Section (a) would cause a Stock Option
or Successor Stock Option to terminate earlier than if such accelerated vesting
had not occurred, then the term of such Stock Option shall not expire earlier
than if such accelerated vesting had not occurred.

4. Cashout of Stock Options. If the Stock Options do not continue to be
outstanding following the Change in Control and are not exchanged for or
converted into Successor Options, each holder of a vested and exercisable option
shall be entitled to receive, as soon as practicable following the Change in
Control, for each share of Common Stock subject to a vested and exercisable
option, an amount of cash determined by the Committee prior to the Change in
Control but in no event less than the excess of the Change in Control Price over
the exercise price thereof (subject to any existing deferral elections then in
effect). If the consideration to be paid in a Change in Control is not entirely
shares of common stock of an acquiring or resulting corporation, then the
Committee may, prior to the Change in Control, provide for the cancellation of
outstanding Stock Options at the time of the Change in Control, in whole or in
part, for cash pursuant to this provision or may provide for the exchange or
conversion of outstanding Stock Options at the time of the Change in Control, in
whole or in part, and, in connection with any such provision, may (but shall not
be obligated to) permit holders of Stock Options to make such elections related
thereto as it determines are appropriate.

5. Incentive Stock Options Not Amended. This Section does not apply to any
incentive stock option within the meaning of Section 422 of the Internal Revenue
Code.

(b) Restricted Stock Units and Performance Share Units.

1. Vesting of Restricted Stock Units. Upon the occurrence of a Change in
Control, each unvested restricted stock unit award which is outstanding
immediately prior to the Change in Control under the Plan shall immediately
become fully vested.

2. Vesting of Performance Share Units. Upon the occurrence of a Change in
Control, each unvested performance share unit award which is outstanding
immediately prior to the Change in Control under the Plan shall immediately
become vested in an amount equal to the PSU Pro Rata Amount.

3. Settlement of Restricted Stock Units and Performance Share Units.

(i) If the Common Stock continues to be widely held and freely tradable
following the Change in Control or is exchanged for or converted into securities
of a successor entity that are widely held and freely tradable, then the
restricted stock units and the vested performance share units shall be paid in
shares of Common Stock or such other securities as soon as practicable after the
date of the Change in Control (subject to any existing deferral elections then
in effect).

(ii) If the Common Stock does not continue to be widely held and freely tradable
following the Change in Control and is not exchanged for or converted into
securities of a successor entity that are widely held and freely tradable, then
the restricted stock units and the vested performance share units shall be paid
in cash as soon as practicable after the date of the Change in Control (subject
to any existing deferral elections then in effect).

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(c) Other Provisions.

1. Except to the extent required by applicable law, for the entirety of the
Protection Period, the material terms of the Plan shall not be modified in any
manner that is materially adverse to the Qualifying Participants (it being
understood that this Section (c) of this Schedule shall not require that any
specific type or levels of equity awards be granted to Qualifying Participants
following the Change in Control).

2. During the Protection Period, the Plan may not be amended or modified to
reduce or eliminate the protections set forth in Section (c)(1) of this Schedule
and may not be terminated.

3. The Company shall pay all legal fees and related expenses (including the
costs of experts, evidence and counsel) reasonably and in good faith incurred by
a Qualifying Participant if the Qualifying Participant prevails on his or her
claim for relief in an action (x) by the Qualifying Participant claiming that
the provisions of Section (c)(1) or (c)(2) of this Schedule have been violated
(but, for avoidance of doubt, excluding claims for Plan benefits in the ordinary
course) and (y) if applicable, by the Company or the Qualifying Participant’s
employer to enforce post-termination covenants against the Qualifying
Participant.

4. This section does not apply to any incentive stock option within the meaning
of Section 422 of the Internal Revenue Code.

5. Anything in the Plan as amended by this Schedule notwithstanding, the Company
reserves the right to make such further changes as may be required if and to the
extent required to avoid adverse consequences under the American Jobs Creation
Act of 2004, as amended.

(d) Definitions. For purposes of this Schedule, the following terms shall have
the following meanings:

1. “Change in Control” shall have the meaning set forth in the Company’s Change
in Control Separation Benefits Plan; provided, however, that, as to any award
under the Plan that consists of deferred compensation subject to Section 409A of
the Code, the definition of “Change in Control” shall be deemed modified to the
extent necessary to comply with Section 409A of the Code.

2. “Change in Control Price” shall mean, with respect to a share of Common
Stock, the higher of (A) the highest reported sales price, regular way, of such
share in any transaction reported on the New York Stock Exchange Composite Tape
or other national exchange on which such shares are listed or on the Nasdaq
National Market during the 10-day period prior to and including the date of a
Change in Control and (B) if the Change in Control is the result of a tender or
exchange offer, merger, or other, similar corporate transaction, the highest
price per such share paid in such tender or exchange offer, merger or other,
similar corporate transaction; provided that, to the extent all or part of the
consideration paid in any such transaction consists of securities or other
non-cash consideration, the value of such securities or other non- cash
consideration shall be determined by the Committee.

3. “Key R&D Options” shall mean those performance-based options granted to
employees under the Key Research and Development Program described in the
applicable Schedule to the Rules and Regulations for the Plan, if any.

4. “Protection Period” shall mean the period beginning on the date of the Change
in Control and ending on the second anniversary of the date of the Change in
Control.

5. “PSU Pro Rata Amount” shall mean for each Performance Share Unit award, the
amount

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determined by multiplying (x) and (y), where (x) is the number of Target Shares
subject to the Performance Share Unit award times the Assumed Performance
Percentage and (y) is a fraction, the numerator of which is the number of whole
and partial calendar months elapsed during the applicable performance period
(counting any partial month as a whole month for this purpose) and the
denominator of which is the total number of months in the applicable performance
period. The Assumed Performance Percentage shall be determined by (1) averaging
the ranks during the Award Period as follows: (A) as to any completed
performance year as of the Change in Control, the actual rank (except that, if
fewer than 90 days have elapsed since the completion of such performance year,
the Target Rank shall be used), and (B) as to any performance year that is
incomplete or has not yet begun as of the Change in Control, the Target Rank,
(2) rounding the average rank calculated pursuant to the foregoing clause (1) to
the nearest whole number using ordinary numerical rounding, and (3) using the
Final Award Percentage associated with the number determined in the foregoing
clause (2). The Target Rank is the rank associated with 100% on the chart of
Final Award Percentages.

6. “Qualifying Participants” shall mean those individuals who participate in the
Plan (whether as current or former employees) as of immediately prior to the
Change in Control.

(e) Application. This Schedule shall apply to Stock Options, restricted stock
unit awards and performance share unit awards under the Plans granted prior to
November 24, 2004.