Muscle damage associated with taking statins

Simavastin. Photo / file

International research shows a commonly used cholesterol-lowering drug can cause the risk of serious muscle damage, but University of Otago researchers say the risk is minimal.

A new study published in the International Journal of Cardiology found people taking a daily dose of 40mg of simvastatin - one of the statin drugs used to prevent heart attacks and strokes - were about five times as likely to develop rhabdomyolysis when compared with people taking 20mg daily.

Rhabdomyolysis is a condition in which the breakdown of muscle tissue can lead to acute kidney failure.

Despite the research, University of Otago researchers say the condition was still very rare in people taking the drug.

Study lead investigator Dr Lianne Parkin said the risks affected about 11 in every 100,000 for those taking the 40mg dose of the drug and two in every 100,000 for those taking the 20mg dose for a one-year course.

Recent meta-analyses clearly showed the benefits of statins in preventing major cardiovascular events far outweighed any serious adverse effects associated with their use, she said.

"However, these meta-analyses were based on highly selected participants in randomised controlled trials and there was very little information about the risk of rhabdomyolysis in people taking the doses of simvastatin that are recommended for use in New Zealand,'' Dr Parkin said.

"While previous research has found a greater risk of serious muscle damage in people taking higher doses of statins, our study is the largest investigation to date of rhabdomyolysis in a general population of simvastatin users and the first to provide separate estimates of risk for 40mg and 20mg simvastatin.''

The researchers, funded by Medsafe and the Health Research Council of New Zealand, used routinely collected health and prescription medicine data to conduct a study based on 313,552 people of all ages who were dispensed simvastatin at any time between 2005 and 2009.

Factors, including age, sex, medical conditions, and other prescription drugs, were taken into account.

"Statins are one of the most widely used classes of drugs and it is reassuring to have found a very low risk of rhabdomyolysis in New Zealanders using simvastatin,'' Dr Parkin said.

The greater risk associated with the use of the 40mg dose of the drug was one of several factors which patients and their doctors should consider when discussing the balance of benefits and risks of cholesterol-lowering treatment, she said.