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)