The Food and Drug Administration on Wednesday announced new safety restrictions on high-dose simvastatin, also known as Zocor, a cholesterol-lowering drug taken by an estimated 2.1 million Americans.
The agency said the 80-milligram dose caused a potentially severe muscle disease, called myopathy, especially in the first year of taking the medication.
No new patients should be put on the high dosage, the F.D.A. said, recommending that existing patients should continue only if they have used the drug for more than a year without experiencing muscle pains. Alternative statins may be safer, the agency said.
The drug’s manufacturer, Merck, advised patients on Wednesday to talk to their doctors if they wanted to change their statin drug or dosage. The company said many patients would not be affected by the F.D.A. action because they were taking lower dosages or had not felt muscle pain.
The F.D.A. approved 80-milligram Zocor in 1998, seven years after it approved lower dosages of the drug. It was once Merck’s top-selling product. Since the patent expired in 2006, simvastatin has mostly been sold as a generic drug.
The new restriction also applies to Vytorin, a combination drug sold by Merck and Schering-Plough that has some formulations in the 80-milligram dose.
And the restriction applies to Simcor, a combination pill sold by Abbott Laboratories. Simcor has lower levels of simvastatin, but may cause higher levels in the body interacting with other drugs, like blood pressure medicines amlodipine and diltiazem.
“I think this is overdue,” said Dr. Steven E. Nissen, chairman of cardiovascular medicine at the Cleveland Clinic. “Most experts in the field have known for many years that these high doses of Zocor were not safe compared with the other statins.”
Two other statins are more potent and can accomplish the same cholesterol targets at lower doses, he said, citing Pfizer’s Lipitor and AstraZeneca’s Crestor.
Some doctors have prescribed simvastatin because it is cheaper in generic form. Lipitor goes off patent in November.
Muscle aches have long been known as a possible side effect of statins. The F.D.A. issued a safety warning on high-dose simvastatin in March 2010. On Wednesday, it said a seven-year study and patient reports prove that patients taking the higher dosage have a higher risk of muscle injury than those taking a lower dose of the drug or taking other statins.
The high doses accounted for 11.7 percent of 94 million simvastatin prescriptions in the United States last year and 15.5 percent of 8.6 million Vytorin prescriptions, the industry research firm IMS Health said.
Dr. Michael Rosenblatt, chief medical officer for Merck, said the higher dose was developed to address medical thinking that the lower a patient’s cholesterol level, the better. “Whatever we did was good enough for the F.D.A., and this is a very important concept in the field,” he said in an interview Wednesday.
“Many people who take simvastatin will not be affected by these label updates,” Dr. Rosenblatt added in a statement. “We encourage those who think these changes might affect them to talk to their doctor.”
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