FDA: Simvastatin and Amiodarone Don't Mix

Rockville, MDThe US Food and Drug Administration (FDA) announced Friday that it is concerned about recent reports of adverse reactions stemming from the combination of simvastatin, a cholesterol drug, and amiodarone. The latter is a common heart drug used to treat an irregular heartbeat.

The agency reports that it continues to receive adverse incident reports relating to the emergence of rhabdomyolysis, a rare type of muscle injury, which—if left untreated—can lead to kidney failure or even death.

Amiodarone is marketed as Cordarone, or Pacerone.

Simvastatin, meanwhile, is found in Merck & Co's Zocor and generic Zocor as well as Simcor, which is marketed by Abbott Laboratories Inc. Simvastatin is also reported to be one of two components making up Vytorin, which is a joint project of Merck and Schering-Plough.

As an aside, Vytorin has recently been implicated as being minimally effective in prolonging life by reducing the amount of plaque in arteries, even though aggressive marketing touted the drug as being particularly effective. Doctors have since been advised by their colleagues in the medical watchdog community that Vytorin should be used as a pathway of last resort for the control of problematic cholesterol.

Drugs historically behave differently in different people, but also when combined with other drugs. In this case, there is concern for anyone taking a cholesterol drug containing simvastatin, together with a heart drug containing amiodarone.

It has been reported that the danger is higher for patients prescribed more than 20 milligrams per day of the cholesterol drugs. As well, according to information reported by the Associated Press (AP) statins—which are considered extremely effective in lowering cholesterol levels and promoting a reduction of arterial plaque—also pose a risk for muscle injury, particularly in the elderly.

The FDA, it has been reported, last warned about this in 2002, and while the incidence rate appears to be low—52 reports received by the FDA over the past six years—the seriousness of those reactions has prompted the FDA to revive the warning and give it a fresh voice. Almost all of the 52 patients suffering adverse reactions were hospitalized.

The warning label for simvastatin was modified in 2002. While the FDA says that the precise mechanism for the reaction(s) had yet to be identified, the agency has said that the fallout from the combination of both drugs related to the fact that amiodarone inhibits the cytochrome P450 3A4 (CYP3A4) enzyme. That's the same enzyme that metabolizes simvastatin.

The above-noted medications for the treatment of cholesterol and irregular heart beat respectively are fairly common. While the FDA has not yet stated if it has any intent to mandate a further change to the simvastatin label, the agency has said that it is working with the manufacturer of Cordarone to revise the prescribing information to warn of the increased risk of rhabdomyolysis when amiodarone is taken with simvastatin in doses which exceed 20 mg daily.

Based on the warning issued by the FDA in 2002, your doctor should have been apprised of the risk inherent with the combination of these two drugs. If your physician failed to warn you of these adverse effects, or worse—if you have been injured as a result—you might want to take the matter up with a qualified attorney.