ACHIEVE Imaging Study Discontinued

Merck & Co., Inc. today announced the discontinuation of ACHIEVE (An Assessment of Coronary Health Using an Intima-Media Thickness Endpoint for Vascular Effects), an imaging study evaluating MK-0524A (ER niacin/laropiprant) in patients with Heterozygous Familial Hypercholesterolemia (HeFH). The study was discontinued at the recommendation of the Steering Committee based on its review and evaluation of scientific data from recent carotid intima-media thickness (cIMT) studies. This decision follows the March 29 Steering Committee recommendation to put patient enrollment on hold. The action to discontinue the study is not related to the recent Not Approvable FDA letter on MK-0524A, and preliminary data did not suggest any safety concerns. "It was clear from the Steering Committee's review of pooled data from recently completed cIMT studies of other medicines that the patient population being studied in ACHIEVE was no longer the correct population to test the primary study hypothesis of IMT progression," said John Kastelein, M.D. Ph.D., Chair, ACHIEVE Steering Committee, Academisch Medisch Centrum, Amsterdam, The Netherlands. "For that reason, the Committee recommended that ACHIEVE be stopped and a new imaging trial be considered in a more appropriate patient population." "The Steering Committee strongly believes that atherosclerosis imaging trials can provide valuable information to scientists and physicians about the risk of vascular disease and the effectiveness of treatments" said Christie Ballantyne, M.D., Chief, Section of Atherosclerosis and Vascular Medicine, Baylor College of Medicine and the Methodist DeBakey Heart Center. "There is significant value in evaluating the effect of medicines in the right patient population using this technology." Merck has notified study investigators of the decision and is in the process of informing regulatory agencies. The Steering Committee will present and publish the results of their review of scientific data from several cIMT studies in HeFH patients at an appropriate scientific forum in the future. Merck remains committed to the development of MK-0524A and, as such, all other ongoing clinical studies, including the 20,000 patient outcomes study known as HPS2-THRIVE, continue unchanged. About ACHIEVE ACHIEVE was designed to evaluate the effects of MK-0524A on cIMT in patients with HeFH. The study was initiated in October 2006 and approximately one-third of the planned 900 patients are currently enrolled. For more information, go to www.clinicaltrials.gov. The ACHIEVE Steering Committee met on May 14, 2008. The Steering Committee members are: Kastelein; Ballantyne; David Marais, M.D., Groote Schuur Hospital & University of Cape Town, South Africa; Claude Gagne, M.D., Clinic of Lipid Disease of Quebec Inc.; Jonathan Isaacsohn, MedPace, Inc.; and Yale Mitchel, M.D., Merck Research Laboratories, Rahway, NJ. 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. 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 are based on management's current expectations and involve risks and uncertainties, which may cause results to differ materially from those set forth in the statements. The forward-looking statements may include statements regarding product development, product potential or financial performance. No forward-looking statement can be guaranteed and actual results may differ materially from those projected. Merck undertakes 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 Merck's business, particularly those mentioned in the risk factors and cautionary statements in Item 1A of Merck's Form 10-K for the year ended Dec. 31, 2007, and in any risk factors or cautionary statements contained in the Company's periodic reports on Form 10-Q or current reports on Form 8-K, which the Company incorporates by reference.