U.S. warns of muscle damage when heart drugs combined

WASHINGTON (Reuters) - U.S. health officials warned the public on Friday about the risk of a rare type of muscle injury seen when the cholesterol drug simvastatin is combined with the anti-arrhythmia medicine amiodarone.

The Food and Drug Administration said it continued to receive reports of rhabdomyolysis, a type of muscle injury that can lead to kidney failure or death, despite a 2002 warning about combining the drugs.

Simvastatin is an ingredient in Merck & Co's Zocor and Abbott Laboratories Inc's Simcor, and is sold generically. It also is one of two components in Merck and Schering-Plough Corp's Vytorin.

Amiodarone is an ingredient in Wyeth's Cordarone and is also sold generically. Upsher-Smith sells a version under the name Pacerone. The drug is used to control a life-threatening type of abnormal heart beat.

All drugs in the statin class of medicines, which include simvastatin, Pfizer Inc's Lipitor and others, carry a potential risk of rhabdomyolysis.

But compared with other statins, the risk is "more pronounced" when simvastatin is given with amiodarone, the FDA said. The risk increased with simvastatin doses greater than 20 milligrams per day.

"Prescribers should be aware of the increased risk of rhabdomyolysis when simvastatin is prescribed with amiodarone, and they should avoid doses of simvastatin greater than 20 mg per day in patients taking amiodarone," the FDA said in a notice on its website.

The FDA has confirmed 52 U.S. reports of rhabdomyolysis associated with use of amiodarone and simvastatin since the 2002 warning, agency spokeswoman Susan Cruzan said. During the same period, there were six cases linked with use of other statins and amiodarone, she said.

Patients should contact a doctor immediately if they develop unexplained muscle cramps, pain, tenderness, stiffness or spasms, the FDA said.

The muscle injury risk has been "very clearly stated" on Zocor's label since 2002, Merck spokesman Ron Rogers said.

Schering-Plough spokesman Lee Davies also said the risk was noted in Vytorin's prescribing instructions for years, and Abbott spokeswoman Elizabeth Hoff said the "prescribing information for Simcor already contains this information."

Wyeth noted a possible interaction specifically with simvastatin on Cordarone's label about six months ago, company spokesman Doug Petkus said. Earlier information mentioned a risk when combining Cordarone with Lipitor and implied it would apply to other statins, he said.

(Additional reporting by Lisa Lambert, editing by Leslie Gevirtz)