Government advisers rejected on Thursday Merck's bid for over-the-counter sales of Mevacor, the cholesterol-lowering drug.

Too many people would mistakenly use the drug if it no longer required a prescription, advisers to the Food and Drug Administration concluded in a 10-to-2 vote against the nonprescription sales.

''The patients couldn't figure out whether the drug was for them,'' said one F.D.A. adviser, Dr. William Shrank of Harvard Medical School.

Merck argued that offering a low dose of Mevacor on drugstore shelves would persuade millions of people with moderately high cholesterol levels to take a pill that might prevent a first heart attack.

''We are disappointed,'' said Edwin Hemwall, executive director for Merck's worldwide nonprescription regulatory and scientific affairs. ''We felt we presented a compelling case.''

The advisers, however, were struck by how many people, in a study of almost 1,500 potential customers, wanted to buy the drug even though they were bad candidates.

A quarter of people who wanted the pill did not have a high enough risk of heart disease to qualify, meaning they would face unnecessary side effects.

Worse still, 30 percent of very high-risk people -- those who have heart disease or diabetes or had survived a stroke -- wanted Mevacor; these are people who should be under a doctor's care. Merck said many of them were not seeing a doctor and that a little treatment was better than none.

Yet more than 30 percent of patients already taking prescription cholesterol-lowering drugs said they wanted the over-the-counter version. Half said they would drop the more potent drug in favor of low-dose Mevacor. To the F.D.A. advisers, that raises questions about previously protected people setting themselves up for a heart attack.

''That's not good,'' said Dr. Kenneth Burman of Washington Hospital Center. ''They're not getting monitored, they're not getting other medications and they're not getting counseling.''

Arthur A. Levin, director of the Center for Medical Consumers in New York, told Merck: ''What I keep hearing from you is, 'It's good to be on a statin, it's good to be on a statin.' Don't you think that's a risk, that they may misdiagnose themselves and take too low a dose?''

The agency is not bound by its advisers' recommendations, but usually follows them. It has said no to over-the-counter Mevacor twice before, in 2000 and again in 2005.

Merck argues that with heart disease still the nation's No. 1 killer, people have become sophisticated enough about cholesterol to try Mevacor.