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Merck Undercuts Popular Notion That Niacin Prevents Heart Attacks

Niacin, a B vitamin that raises "good" cholesterol, has failed to benefit heart disease patients when taken in tandem with a statin drug that lowers "bad" cholesterol, according to drug maker Merck.

Patients taking the niacin-statin combo had no fewer heart attacks, strokes or artery-clearing procedures than those taking simvistatin alone, the company said Thursday. And it may have caused serious harm to some of the 25,000 patients in Europe and China involved in the study.

The large niacin-plus-simvistatin study may have far-reaching implications, since millions of people take niacin every day on their doctors' belief that it will prevent heart attacks and strokes.

Dr. Steven Nissen of Cleveland Clinic says in an email to Shots that "phones will ring off the hook in cardiology practices throughout America" because of the news.

The company didn't specify the nature or magnitude of the harmful effect, but a study last year suggested that patients taking niacin plus simvistatin had a slightly higher risk of strokes. That study, called AIM-HIGH, was stopped early because it showed no benefit either.

Merck says it has abandoned its plan to seek Food and Drug Administration approval of its niacin drug, called Tredaptive. The drug is already licensed in 70 countries. The FDA earlier declined to approve it until it got the results of the just-completed study.

Nissen says he frequently prescribes niacin to patients who have low HDL. "I won't start new patients" on it, he tells Shots, but he won't tell patients on niacin to stop taking it until he has a chance to review Merck's published study, which presumably won't be out for some months.

Nissen has been a proponent of finding drugs that raise HDL, which stands for high-density lipoprotein. For years the dogma has been that HDL scavenges harmful LDL, or low-density lipoprotein, from the bloodstream so it can be excreted in bile. Therefore, raising HDL should be a good thing.

But other recent studies besides the new Merck data have called this into question. The HDL-raisers torcetrapid and dalcetrapib failed to show benefit. And a large study earlier this year found that people who are genetically predisposed to have higher HDL levels have no less heart disease than those with genes that yield somewhat lower levels.

Nissen says he's "unwilling to abandon" the hypothesis that raising HDL lowers heart disease. "Nevertheless," he acknowledges, "this is a serious blow to the theory."

The Cleveland researcher thinks that using drugs to raise HDL involves complicated mysteries about very different effects from different medications.

One unknown in the Merck study is whether a second drug called laropiprant that was combined with niacin in Tredaptive may have blunted a beneficial effect of niacin or caused adverse effects. Laropiprant, which is designed to counter the flushing that many patients experience with niacin, didn't show ill effects in earlier studies, Nissen says.

Copyright 2012 National Public Radio. To see more, visit http://www.npr.org/.

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