Sanofi-aventis to Acquire Merck's Interest in Merial

Agreement includes option for sanofi-aventis to combine Merial with
Intervet/Schering-Plough Animal Health in new equally owned joint venture with
the new Merck

Future joint venture would be a global leader in animal health
PARIS & WHITEHOUSE STATION, N.J. & KENILWORTH, N.J.--(Business Wire)--
Sanofi-aventis (EURONEXT: SAN and NYSE: SNY) and Merck & Co., Inc. (NYSE: MRK)
today announced that the companies have signed a definitive agreement under
which Merck will sell its 50 percent interest in the companies' current animal
health joint venture, Merial Limited (Merial), to sanofi-aventis for $4 billion
(US) in cash. Formed in 1997, Merial is a leading animal health company that is
a 50/50 joint venture between Merck and sanofi-aventis. Following the close of
the transaction, sanofi-aventis will own 100 percent of Merial.

Sanofi-aventis said the acquisition price values Merial on the basis of 3.0 x
2008 sales and 10.2 x 2008 earnings before interest and taxes (EBIT). The
acquisition is expected to be accretive to sanofi-aventis' adjusted net income
from the first year.

In addition to the Merial agreement, Merck, sanofi-aventis and Schering-Plough
announced the signing of a call option agreement. Under the terms of the call
option agreement, following the closing of the Merck/Schering-Plough merger,
sanofi-aventis would have an option to combine the Intervet/Schering-Plough
Animal Health business with Merial to form an animal health joint venture that
would be owned equally by the new Merck and sanofi-aventis.

"These agreements should enable us to proceed expeditiously with the closing of
our merger with Schering-Plough in the fourth quarter as planned, and also gain
an outstanding animal health business through Intervet/Schering-Plough Animal
Health," said Richard T. Clark, Merck chairman, president and chief executive
officer. "We are pleased that our long-time partner sanofi-aventis will purchase
Merck's interest in Merial, the successful joint venture we built together," he
added. "We look forward to the potential opportunity to bring together the
strong animal health businesses of sanofi-aventis and the new Merck."

Commenting on these agreements, Christopher A. Viehbacher, Chief Executive
Officer of sanofi-aventis said: "We are pleased with the acquisition of Merial,
a major global player in animal heath, and the possibility of combining Merial
and Intervet/Schering-Plough's complementary businesses. The combination would
create a new leader in this USD 19 billion global animal health market,
supporting our vision of a global diversified healthcare leader. In an
environment of increasing complexity, I am convinced that alliances have an
important place and I look forward to the prospect of further partnering with
the new Merck in animal health to build on our longstanding relationship."

The sale of Merck's interest in the Merial joint venture is subject to clearance
by the European antitrust authorities. Merck said it anticipates completing the
transaction before its planned merger with Schering-Plough is finalized, which
is expected to occur during the fourth quarter of 2009. Following the close of
Merck's merger with Schering-Plough, sanofi-aventis would have an opportunity to
conduct due diligence before any exercise of its call option to form the new
joint venture.

As part of the call option agreement, the value of Merial has been fixed at $8
billion (US). The minimum total value received by the new Merck and its
affiliates by contributing Intervet/Schering-Plough to the combined entity would
be $9.25 billion (US), consisting of a floor valuation of
Intervet/Schering-Plough of $8.5 billion (US) (subject to potential upward
revision based on a valuation exercise by the two parties) and an additional
payment of $750 million (US). Based on the valuation exercise of
Intervet/Schering-Plough and customary transaction adjustments, if Merial and
Intervet/Schering-Plough are combined, a true-up payment would be paid to
establish a 50/50 joint venture with equal ownership between the new Merck and
sanofi-aventis. Any formation of a new animal health joint venture with
sanofi-aventis is subject to customary closing conditions including antitrust
review in the United States and Europe.

Between September 30, 2009 and the closing of the merger between Merck and
Schering-Plough, the agreements provide Merck with certain rights to terminate
the option for a fee of $400 million or $600 million (US).

The companies said Merial and Intervet/Schering-Plough Animal Health will
continue to operate independently until the closing of any potential combination
of Merial and Intervet/Schering-Plough Animal Health.

About Merck

Merck & Co., Inc. is a global research-driven pharmaceutical company dedicated
to putting patients first. Established in 1891, Merck discovers, develops,
manufactures and markets vaccines and medicines to address unmet medical needs.
The Company devotes extensive efforts to increase access to medicines through
far-reaching programs that not only donate Merck medicines but help deliver them
to the people who need them. Merck also publishes unbiased health information as
a not-for-profit service. For more information, visit www.merck.com.

About Sanofi-aventis

Sanofi-aventis, a leading global pharmaceutical company, discovers, develops and
distributes therapeutic solutions to improve the lives of everyone.
Sanofi-aventis is listed in Paris (EURONEXT: SAN) and in New York (NYSE: SNY).

About Schering-Plough

Schering-Plough is an innovation-driven, science-centered global health care
company. Through its own biopharmaceutical research and collaborations with
partners, Schering-Plough creates therapies that help save and improve lives
around the world. The company applies its research-and-development platform to
human prescription, animal health and consumer health care products.
Schering-Plough's vision is to "Earn Trust, Every Day" with the doctors,
patients, customers and other stakeholders served by its colleagues around the
world. The company is based in Kenilworth, N.J., and its Web site is
www.schering-plough.com.

About Merial

Merial is a world-leading, innovation-driven animal health company, providing a
comprehensive range of products to enhance the health, well-being and
performance of a wide range of animals. Merial employs approximately 5,400
people and operates in more than 150 countries worldwide. Merial Limited is a
joint venture between Merck & Co., Inc. and sanofi-aventis. For more
information, please see www.merial.com.

Forward Looking Statements by Sanofi-aventis

This press release contains forward-looking statements as defined in the Private
Securities Litigation Reform Act of 1995, as amended. Forward-looking statements
are statements that are not historical facts. These statements include product
development, product potential projections and estimates and their underlying
assumptions, statements regarding plans, objectives, intentions and expectations
with respect to future events, operations, products and services, and statements
regarding future performance. Forward-looking statements are generally
identified by the words "expects," "anticipates," "believes," "intends,"
"estimates," "plans" and similar expressions. Although sanofi-aventis`
management believes that the expectations reflected in such forward-looking
statements are reasonable, investors are cautioned that forward-looking
information and statements are subject to various risks and uncertainties, many
of which are difficult to predict and generally beyond the control of
sanofi-aventis, that could cause actual results and developments to differ
materially from those expressed in, or implied or projected by, the
forward-looking information and statements. These risks and uncertainties
include among other things, the uncertainties inherent in research and
development, future clinical data and analysis, including post marketing,
decisions by regulatory authorities, such as the FDA or the EMEA, regarding
whether and when to approve any drug, device or biological application that may
be filed for any such product candidates as well as their decisions regarding
labelling and other matters that could affect the availability or commercial
potential of such products candidates, the absence of guarantee that the
products candidates if approved will be commercially successful, the future
approval and commercial success of therapeutic alternatives, the Group`s ability
to benefit from external growth opportunities as well as those discussed or
identified in the public filings with the SEC and the AMF made by
sanofi-aventis, including those listed under "Risk Factors" and "Cautionary
Statement Regarding Forward-Looking Statements" in sanofi-aventis` annual report
on Form 20-F for the year ended December 31, 2008. Other than as required by
applicable law, sanofi-aventis does not undertake any obligation to update or
revise any forward-looking information or statements.

Forward Looking Statements by Schering-Plough

This communication also includes "forward-looking statements" within the meaning
of the safe harbor provisions of the United States Private Securities Litigation
Reform Act of 1995. Such statements may include, but are not limited to,
statements about the benefits of the proposed merger between Merck and
Schering-Plough, the timing and completion of the sale of Merck`s interest in
Merial to sanofi-aventis, the exercise of sanofi-aventis`s call option, and
other statements that are not historical facts. Such statements are based upon
the current beliefs and expectations of Merck`s and Schering-Plough`s management
and are subject to significant risks and uncertainties. Actual results may
differ from those set forth in the forward-looking statements.

The following factors, among others, could cause actual results to differ from
those set forth in the forward-looking statements: the ability to obtain
governmental and self-regulatory organization approvals of the merger on the
proposed terms and schedule; the failure of Schering-Plough or Merck
stockholders to approve the merger; the possibility that the merger does not
close, including, but not limited to, due to the failure to satisfy the closing
conditions; the ability to obtain governmental approvals of the sale of Merck`s
interest in Merial to sanofi-aventis; and the failure of sanofi-aventis to
exercise the call option. Schering-Plough undertakes no obligation to publicly
update any forward-looking statement, whether as a result of new information,
future events or otherwise. Additional factors that could cause results to
differ materially from those described in the forward-looking statements can be
found in Schering-Plough's Quarterly Report on Form 10-Q for the period ended
June 30, 2009, the merger proxy statement/prospectus filed June 25, 2009, and
Schering-Plough's other filings with the Securities and Exchange Commission (the
"SEC") available at the SEC`s Internet site (www.sec.gov).

Forward Looking Statements by Merck

This communication also includes "forward-looking statements" within the meaning
of the safe harbor provisions of the United States Private Securities Litigation
Reform Act of 1995. Such statements may include, but are not limited to,
statements about the benefits of the proposed merger between Merck and
Schering-Plough, including future financial and operating results, the combined
company`s plans, objectives, expectations and intentions and other statements
that are not historical facts. Such statements are based upon the current
beliefs and expectations of Merck`s and Schering-Plough`s management and are
subject to significant risks and uncertainties. Actual results may differ from
those set forth in the forward-looking statements.

The following factors, among others, could cause actual results to differ from
those set forth in the forward-looking statements: the possibility that the
expected synergies from the proposed merger of Merck and Schering-Plough will
not be realized, or will not be realized within the expected time period, due
to, among other things, the impact of pharmaceutical industry regulation and
pending legislation that could affect the pharmaceutical industry; the ability
to obtain governmental and self-regulatory organization approvals of the merger
on the proposed terms and schedule; the actual terms of the financing required
for the merger and/or the failure to obtain such financing; the failure of
Schering-Plough or Merck stockholders to approve the merger; the risk that the
businesses will not be integrated successfully; disruption from the merger
making it more difficult to maintain business and operational relationships; the
possibility that the merger does not close, including, but not limited to, due
to the failure to satisfy the closing conditions; Merck`s ability to accurately
predict future market conditions; dependence on the effectiveness of Merck`s
patents and other protections for innovative products; the risk of new and
changing regulation and health policies in the U.S. and internationally and the
exposure to litigation and/or regulatory actions. Merck undertakes no obligation
to publicly update any forward-looking statement, whether as a result of new
information, future events or otherwise. Additional factors that could cause
results to differ materially from those described in the forward-looking
statements can be found in Merck`s 2008 Annual Report on Form 10-K, Current
Report on Form 8-K filed on June 22, 2009, Merck's other filings with the
Securities and Exchange Commission (the "SEC") available at the SEC`s Internet
site (www.sec.gov).

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Media:
Merck
David Caouette, 908-423-3461
or
sanofi-aventis
Jean-Marc Podvin, +33 1 53 77 44 50
or
Schering-Plough
Fred Malley, 908-298-7428
or
Investors:
Merck
Eva Boratto, 908-423-5185
or
sanofi-aventis
Sébastien Martel, +33 1 53 77 4545
or
Schering-Plough
Janet Barth, 908-298-7436

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