The U.S. Food and Drug Administration issued a warning Friday about using high doses of the popular cholesterol-lowering drug Zocor -- generic name simvastatin -- and the increased risk of serious muscle injury.

The FDA says the warning involves patients taking "the highest approved dose of the cholesterol-lowering medication, Zocor (simvastatin) 80 mg, compared to patients taking lower doses of simvastatin and possibly other drugs in the 'statin' class."

The FDA points out that muscle injury, "also called myopathy, is a known side effect with all statin medications." Its symptoms include muscle pain, tenderness or weakness. In a worst-case scenario, myopathy can cause kidney damage or life-threatening kidney failure.

Based on interim results from an on-going clinical trial, the FDA has also approved a labeling revision for the drug -- saying that "patients of Chinese descent should not receive simvastatin 80 mg with cholesterol-modifying doses of niacin-containing products."

Simvastatin is sold as a single-ingredient medication, Zocor, by New Jersey-based Merck & Co. (MRK) It is also used as part of other cholesterol-lowering drugs and is sold as a generic.

Merck issued a statement shortly after the FDA report. "Simvastatin, when used as a supplement to a healthy diet, can help reduce LDL cholesterol and reduce the risk of death from cardiovascular disease in patients at high risk of coronary events," said Dr. Michael Rosenblatt, the company's chief medical officer. "We support the FDA's recommendation that patients continue taking their medication as prescribed by their physicians, and that patients speak to their physician if they have symptoms or questions."