The condition may in turn develop if the treatment with Zocor is continued into rhabdomyolysis - a severe life threatening condition.

Although muscle pain and weakness, called myopathy, is a known side effect of all cholesterol-lowering drugs classified as statins, such as Zocor, the FDA said that people taking the 80 milligram dose face an especially high risk of developing muscle problems, including rhabdomyolysis, the most serious form of myopathy, which can lead to kidney damage, kidney failure and even death.

Reacting to the warning, Dr. Gregg Fonarow, a professor of cardiovascular medicine at the University of California, Los Angeles, said that patients shouldn't lose sight of the benefits of statin use.

"Statins, including Zocor, have been shown to lower the risk of heart attack, strokes and premature cardiovascular deaths, and in most patients the benefits of statin treatment greatly outweigh the risks," he said.

As mentioned above all of the drugs currently on the market which belong to the statin class may cause muscle related side-effects. The doses of Zocor of 10 mg, 20 mg, 40 mg miligrams have the same adverse effect profile, however the 80 mg dosage of the preparation when used has shown increased risk of muscle injury, especially in patients who use other drugs which interact with Zocor.

"There are other statin medications which lower LDL - bad cholesterol - levels as well or better than the simvastatin 80 milligram dose and without the same degree of muscle injury risk," he said. "Patients should discuss with their physician which statin regimen and dosing is most appropriate for them."

The agency is advising patients taking the drug to talk with their doctors, before stopping or changing their medication. "Review of simvastatin is part of an ongoing FDA effort to evaluate the risk of statin-associated muscle injury and to provide that information to the public as it becomes available, Dr. Eric Colman, deputy director of FDA's Division of Metabolism and Endocrinology Products, said in a statement. "It's important for patients and health care professionals to consider all the potential risks and known benefits of any drug before deciding on any one therapy or dose of therapy," he said.

Before the warning was issued the FDA considered data from a number of clinical trials, observational studies as well as adverse event reports and prescription data.

In addition, the FDA is looking over data from the Study of the Effectiveness of Additional Reductions in Cholesterol and Homocysteine (SEARCH), which studied heart attack, revascularization and cardiovascular death in patients taking 80 milligrams of Zocor, compared with patients taking 20 milligrams. The trial also included data on muscle injury.

The active ingredient of Zocor is Simvastatin. Which is also sold under different Generic names. Simvastatin is also a part of a combined preaparation called Vitorin and Simcor.