Cholesterol drug Zocor (simvastatin) dangerous at high doses, FDA says

(CBS/AP) Is Zocor dangerous? The FDA is warning that high doses of the blockbuster cholesterol drug can harm muscles and cause potentially deadly kidney damage. It's added new warnings to Zocor in an effort to caution doctors about prescribing the drug in high doses.

Regulators said Wednesday that patients taking the 80-milligram dose of Zocor or generic simvastatin are at higher risk than patients taking lower doses of the drug or other statins.

The 80-milligram dose should be used only in patients who have taken it for more than a year without signs of injury. New patients should start on a lower dose, the agency said.

FDA-approved doses for the drug range from 5 milligrams to 80 milligrams.

More than 2.1 million patients in the U.S. were given a prescription for the Zocor or generic simvastatin last year, according to the FDA. Zocor's maker, Merck, said about 12 percent of patients currently take the highest dose of the drug.

"This is an important medicine for these patients because they are at the highest risk for heart disease," said Dr. Michael Rosenblatt, Merck's chief medical officer. "Patients shouldn't stop taking this medicine on their own. They should talk to their doctor."

Patients suffering from the muscle injury, called myopathy, experience pain, tenderness, weakness, and elevation of a muscle enzyme called creatine kinase. The most serious form of myopathy, called rhabdomyolysis, can cause fatal injury to the kidneys. The condition is rare, affecting about 5 out of every 100,000 people taking Zocor for a year.

Other statin drugs - including Lipitor (atorvastatin) and Crestor (rosuvastatin) - can lower cholesterol levels with a smaller risk for muscle injury, Dr. Gregg C. Fonarow, professor of cardiology at the University of California at Los Angeles, told Healthday. He added, "Patients should consider taking this opportunity to discuss with their physician which statin regimen may be most appropriate to improve their cardiovascular health.

The FDA has more on Zocor.