Patients on the highest approved dose of the cholesterol-lowering drug Zocor may be at increased risk of muscle injury, U.S. regulators warned on Friday.

Made by Merck & Co and sold under the brand name Zocor, simvastatin is also sold in combination with ezetimibe as Vytorin, and in combination with niacin as Abbott Laboratories Simcor, the U.S. Food and Drug Administration said in a statement. Simvastatin also is available as a single-ingredient generic medication.

The FDA said its review of simvastatin is part of an ongoing effort to evaluate the risk of statin-associated muscle injury.

“Although muscle injury… is a known side effect with all statins, the warning highlights the greater risk of developing muscle injury, including rhabdomyolysis, for patients when they are prescribed and use higher doses of this drug,” the agency said in a statement.

The warning follows an FDA review of new information on the risk of muscle injury from clinical trials, studies, adverse event reports and prescription use data, the FDA said.

The FDA said it was also reviewing data from a clinical trial which studied cardiovascular disease in patients prescribed 80 milligrams of simvastatin compared to those on 20 milligrams.

Rhabdomyolysis is the most serious form of muscle disease and can lead to severe kidney damage, kidney failure, and sometimes death, the agency said.

“It’s important for patients and healthcare professionals to consider all the potential risks and known benefits of any drug before deciding on any one therapy or dose of therapy,” said Dr. Eric Colman, deputy director of FDA’s Division of Metabolism and Endocrinology Products.

WASHINGTON (Reuters)

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