Amiodarone + Simvastatin = Increased Risk: FDA

Washington, DCAn adverse reaction to statin use, including amiodarone interaction and simvastatin side effect, was identified by the US Food and Drug Administration (FDA) last year. And while simvastatin rhabdomyolysis is rare, researchers from the University of Western Ontario warned that side effects are likely to increase as more patients were prescribed amiodarone, and as LDL cholesterol targets tightened.

In August the FDA warned that simvastatin use in concert with amiodarone, an anti-arrhythmia drug, could lead to severe complications.

According to the October 7th edition of Pulse, based in the UK, the incidence of life-threatening rhabdomyolysis was found by researchers to languish at 0.1 to 0.2 cases per 1000 person-years, with equal incidence rates in observational studies and the original clinical trials.

However clinical experience with statins seems to suggest that incidence rates for myopathy—a muscular disorder—is at least twice as high in clinical experience than what was determined in clinical trials.

The National Prescribing Centre in the UK says as many as 10 percent of patients may experience myopathy according to real-world clinical experience. That's in sharp contrast to an incidence rate of 1.5 to 5 percent identified in the original clinical trials.

Dr Anthony Wierzbicki, consultant in metabolic medicine at Guy's and St Thomas' Hospital in London, expressed the view that, "the higher figures are plausible but it depends on how you define myopathy. The usually accepted figure is 3 to 5 percent. This effect is definitely dose-related and worse with lipophilic statins such as simvastatin," he said.

Although the side effects were generally clinically benign, they did have an impact on quality of life and led to withdrawals from statin treatment, said the researchers. Such withdrawals are said to affect about 40 percent of the population in England who would otherwise benefit from statin use but, due to the side effects, had stopped taking them.

Experience by the British population could easily translate to the US and North America.

Pulse reports that the latest public health bulletin released by the National Prescribing Center in the UK was prompted by a study published earlier in the summer by the Annals of Internal Medicine.

Dr Rubin Minhas, a doctor from Gillingham, Kent in the UK said, "Myopathy is likely to be more common than trials suggest because reality is more complicated than trials. We should regard the risks from statin trials as a minimum."

He urged doctors to proceed with caution with regard to higher dosages of statins for the elderly, or those with other risk factors for myopathy-- being smaller and frailer, hypothyroidism, alcoholism, high-dose statins and concurrent treatment with fibrates, antifungals, macrolide antibiotics, amiodarone and verapamil, among others.