The U.S. Food and Drug Administration will make the final decision, but usually follows panel recommendations. Merck said an FDA ruling is expected in the first quarter of 2008.

Mevacor is one of the statin drugs taken by millions to cut cholesterol and the risk of heart disease, the leading killer of Americans. Other prescription statins include Merck's Zocor and Pfizer Inc's Lipitor.

Merck is making its third try to win approval of a low-dose, nonprescription version of Mevacor for patients with a moderate risk of heart disease.

Allowing statin sales without a prescription would be a major shift. Nonprescription drugs generally treat short-term conditions with easily recognized symptoms such as a headache or runny nose. High cholesterol can be detected only with a blood test, and patients often take statins for years.

Merck argued before the panel that an estimated 20 million Americans with moderate heart-disease risk could benefit from a statin, but just 6 million of them are on treatment.

Having Mevacor available on drugstore shelves could lure many untreated patients to therapy, said Edwin Hemwall, an official with Merck Research Laboratories.

"Over time, it will reduce the risk of a first heart attack and provide a real impact on public health," Hemwall said.

But panel members questioned if some patients who should not take Mevacor would do so.

Merck tested consumers' understanding of packaging instructions meant to help people decide if they should take Mevacor. In one study, about 30 percent of people with diabetes or a history of heart disease or a stroke wanted to buy Mevacor, FDA reviewers said. The label advised such patients to consult a doctor before use.

Panel members worried that such higher-risk patients might take over-the-counter Mevacor rather than a more-potent prescription statin.

Consumers "may misdiagnose themselves ... and be on inadequate therapy," said panel member Arthur Levin, director of the Center for Medical Consumers.

"Or they might misdiagnose themselves and be on lifetime therapy when there's no need for that therapy," Levin added.

Unnecessary treatment could expose people to risks such as muscle weakness, panelists said.

Merck said it was disappointed with the panel's decision. "We felt we presented a compelling case," Hemwall said in a written statement.

GlaxoSmithKline Plc recently acquired exclusive U.S. rights to sell over-the-counter Mevacor in return for undisclosed milestone and royalty payments to Merck.

Mevacor, known generically as lovastatin, lost patent protection in 2001. An over-the-counter version would receive three years of exclusive marketing time if approved.

If the bid is rejected, the FDA would consider future attempts to move Mevacor over the counter, said Andrea Leonard-Segal, director of the FDA's nonprescription drugs office.

"We're open-minded," she told reporters.

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