Cholesterol Drug Tied to Rhabdomyolysis

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At high doses, the drug simvastatin (Merck, also known as Zocor), puts patients at risk of developing rhabdomyolysis, a severe breakdown of muscle that can result in acute kidney injury, dysfunction, and even death.

In mid-March, the Food and Drug Administation issued a warning message that patients taking the highest allowable dose of Zocor, 80 mg, had an increased risk for muscle injury. The FDA issued the news partly in response to findings from the trial Study of the Effectiveness of Additional Reductions in Cholesterol and Homocysteine (SEARCH).

Known risk factors for developing rhabdomyolysis include age above 65 years old, low thyroid hormone levels (hypothyroidism), and poor kidney function.

According to the FDA, myopathy is a known side effect of all statin medications. In fact, Merck said warnings about myopathy have always been part of the drug information package. “The labeling for simvastatin has reflected information about potential muscle effects since approval,” according to a Merck statement about the FDA announcement.

“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 Michael Rosenblatt, MD, Merck’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.”

The company is working with regulatory agencies to update the drug’s labeling as needed.

The FDA recommends that health care professionals:

  • be aware of the potential increased risk of muscle injury with the 80 mg dose of simvastatin compared to lower doses of simvastatin and possibly other statin drugs.

  • review patients’ medical history and medications to determine whether simvastatin is clinically appropriate for each patient.

  • discuss with patients the benefits and risks, including the risk of myopathy and rhabdomyolysis, of simvastatin therapy.

  • be aware of potential drug-drug interactions with simvastatin.

  • report any adverse events associated with the use of simvastatin to FDA’s MedWatch program. Visit for more information.