FDA Warns Of Deadly Link to Rare Muscle Syndrome with Zocor

People taking the highest approved doses of the cholesterol-lowering drug Zocor (simvastatin) may be at increased risk for muscle injuries, the U.S. Food and Drug Administration (FDA) warned earlier this year. The Zocor drug safety communication also contains a list of drugs that should not be used in combination with Zocor, including the combination cholesterol drugs Vytorin and Simcor. The FDA began reviewing the side effects of Zocor in March 2010, when it first warned of the possible increased risk of rhabdomyolysis and other muscle injuries. The FDA estimates that 2.1 million people were prescribed some drug containing simvastin in 2010. Eleven patients who used 80 milligrams of the statin drug per day developed Zocor rhabdomyolysis compared to none among those

who used only 20 milligrams according to the SEARCH trial.

Rhabdomyolysis from Zocor causes muscle fibers to begin to break down, releasing a protein called myoglobin, which can damage the kidneys as they attempt to filter it out of the bloodstream. Symptoms of rhabdomyolysis include muscle cramps, tenderness, stiffness, pain or spasms. The illness is usually reported in patients over 65 years of age or those who have renal impairment or uncontrolled hypothyroidism. For the safety reason, the FDA suggests patients should not use Zocor if they use itraconazole, ketoconazole, erythromycin, clarithromycin,telithromycin, HIV protease inhibitors, and nefazodone.  Patients on diltiazem may use no more than 40 milligrams of Zocor per day. The new restrictions and warnings also apply to Vytorin and Simcor, which are combination medications that include simvastatin as an active ingredient. Generic versions of simvastatin will also include the myopathy warnings and be subject to dosing restrictions.

Muscle aches are a well-known Zocor side effects and other drugs in the same class, known as statins, and the labels for the class already bear warnings regarding this risk. In 2010, the FDA also issued a safety alert for high-dose simvastatin. According to a report from The New York Times, this latest action on the part of the FDA was prompted by a seven-year study and patient reports that prove those taking the higher dosage have a greater risk of muscle injury than patients treated with lower doses or other statins.