Merck & Co., Inc. and Actelion Form Renin Inhibitor Alliance.

Business Editors/Health/Medical Writers

WHITEHOUSE STATION, N.J. & ALLSCHWIL/BASEL, Switzerland--(BUSINESS WIRE)--Dec. 4, 2003--Merck & Co., Inc., (NYSE:MRK) and Actelion Ltd (SWX:ATLN) have announced today that the two companies have formed an exclusive worldwide alliance to discover, develop and market new classes of renin inhibitors.

This alliance will enable Actelion and Merck to combine their discovery, development and marketing capabilities with the goal to efficiently provide innovative and better medicines to patients suffering from cardio-renal diseases.

Through the formation of a joint committee, the parties will collaborate on the development of products. Development funding will be initially shared by both parties, with Merck fully responsible to fund pivotal Phase III and outcome studies. Merck will lead and fund commercialization. Actelion retains a worldwide option to co-promote any product resulting from this alliance as a paid-for sales force.

Merck will pay Actelion an upfront payment of $10 million. In addition, Actelion will be eligible to receive research, development and approval milestone payments of up to $262 million for the successful commercialization of the first collaboration product. Actelion will also be eligible to receive certain milestone payments for the successful commercialization of additional products. Merck will pay Actelion substantial royalties on the sale of all products resulting from this renin inhibitor alliance.

Alliance to Maximize Scientific Breakthrough in Renin Inhibitor Classes

Actelion's innovative research has resulted in breakthroughs in multiple classes of novel renin inhibitors with excellent oral availability. These highly potent oral renin inhibitors potentially represent the most promising new avenue for significant treatment advances in essential hypertension and other major cardio-renal diseases.

Jean-Paul Clozel, M.D. and chief executive officer of Actelion, commented, "Actelion has made a breakthrough that might significantly improve treatment for patients suffering from serious cardio-renal diseases. We are partnering this program with the best possible partner, Merck. They are an undisputed leader in advancing cardiovascular medicine."

Jean-Paul Clozel continued, "Merck shares our commitment to science and innovation and to bringing breakthrough products to patients in areas with high unmet medical need. Also, Actelion and Merck strongly believe that any partnership must benefit all parties involved, the two companies and the medical and patient communities at large. This alliance will have access to the necessary know-how, resources and marketing power. Together, Actelion and Merck will work to rapidly transform innovative science into beneficial medicine."

"We are extremely enthusiastic about our collaboration with Actelion," said Peter S. Kim, Ph.D., president of Merck Research Laboratories. "Capitalizing on Actelion's innovative research in the area of renin inhibition and Merck's strong expertise in the development and commercialization of medicines for hypertension, we have formed a dynamic partnership. We look forward to working with Actelion toward the goal of providing novel treatments to patients."

"This important relationship with Actelion is another indicator of Merck's determination to work with the best of biotech in constructive ways to strengthen our potential for bringing breakthrough medicines to patients in need," added Mervyn Turner, Ph.D., senior vice president, Worldwide Licensing and External Research for Merck.

About Renin Inhibition

Renin plays a key role in the regulation of blood volume, arterial pressure, and cardiac and vascular function by serving as the first component of the renin-angiotensin system. Renin is an enzyme that catalyzes the formation of the hormone angiotensin I, which is transformed by the angiotensin converting enzyme (ACE) to angiotensin II, which acts on specific receptors to increase blood pressure and modulate long term processes such as arteriosclerosis and remodeling of heart and kidney. Therapeutic manipulation of the renin-angiotensin pathway has become very important in treating hypertension and heart failure.

Renin inhibition is a novel pharmacological approach for hypertension, renal failure, and vascular diseases. Actelion has made substantial progress in improving the oral bioavailability of potent renin inhibitors up to 70 percent, achieving strong effects on blood pressure in animal models.

About Merck

Merck & Co., Inc. is a global research-driven pharmaceutical products company. Merck discovers, develops, manufactures and markets a broad range of innovative products to improve human and animal health, directly and through its joint ventures. Merck has a long history in successfully developing and marketing antihypertensive medicines. Merck entered the antihypertensive arena with DIURIL more than 50 years ago. Subsequently, Merck discovered a series of products including HYDRODIURIL, ALDOMET, MODURETIC, RENITEC, PRINIVIL and, most recently, developed COZAAR and HYZAAR(a) in a collaboration with DuPont. COZAAR/ HYZAAR are currently among the top two prescribed AIIAs in many major markets.

Forward-Looking Statement

This press release contains "forward-looking statements" as that term is defined in the Private Securities Litigation Reform Act of 1995. These statements involve risks and uncertainties, which may cause results to differ materially from those set forth in the statements. The forward-looking statements include statements regarding product development. No forward-looking statement can be guaranteed, and actual results may differ materially from those projected. We undertake no obligation to publicly update any forward-looking statement, whether as a result of new information, future events, or otherwise. Forward-looking statements in this press release should be evaluated together with the many uncertainties that affect our businesses, particularly those mentioned in the cautionary statements in Item 1 of our Form 10-K for the year ended Dec. 31, 2002, and in our periodic reports on Form 10-Q and Form 8-K (if any) which we incorporate by reference.

About Actelion

Actelion Ltd is a biopharmaceutical company with its corporate headquarters in Allschwil/Basel, Switzerland. Actelion's first drug Tracleer(R), an orally available dual endothelin receptor antagonist, has been approved as a therapy for pulmonary arterial hypertension. Actelion markets Tracleer(R) through its own subsidiaries in key markets worldwide, including the United States (based in South San Francisco), the European Union as well as Canada and Switzerland. Actelion, founded in late 1997, is a leading player in innovative science related to the endothelium -- the single layer of cells separating every blood vessel from the blood stream. Actelion focuses on the discovery, development and marketing of innovative drugs for significant unmet medical needs. Actelion shares are traded on the SWX Swiss Exchange (ticker symbol: ATLN).

(a) COZAAR and HYZAAR are registered trademarks of E.I. DuPont de Nemours and Company, Wilmington, Del.