Statins, commonly used for lowering cholesterol levels, can give rise to muscle and cognitive problems, according to a new study.
Beatrice Golomb, MD, PhD, associate professor of medicine at the University of California, San Diego School of Medicine and director of UC San Diego's Statin Study group analysed 900 studies on the adverse effects of HMG-CoA reductase inhibitors (statins).
It also helps explain why certain individuals have an increased risk for such adverse effects.
"Muscle problems are the best known of statin drugs' adverse side effects," said Golomb.
"But cognitive problems and peripheral neuropathy, or pain or numbness in the extremities like fingers and toes, are also widely reported.
"A spectrum of other problems, ranging from blood glucose elevations to tendon problems, can also occur as side effects from statins," she added.
Higher statin doses or more powerful statins - those with a stronger ability to lower cholesterol - as well as certain genetic conditions, are linked to greater risk of developing side effects.
The study showed that statin-induced injury to the function of the body's energy-producing cells, called mitochondria, underlies many of the adverse effects that occur to patients taking statin drugs.
When mitochondrial function is impaired, the body produces less energy and more "free radicals" are produced.
Coenzyme Q10 ("Q10") is a compound central to the process of making energy within mitochondria and quenching free radicals
However, statins lower Q10 levels because they work by blocking the pathway involved in cholesterol production - the same pathway by which Q10 is produced. Statins also reduce the blood cholesterol that transports Q10 and other fat-soluble antioxidants.
Because statins may cause more mitochondrial problems over time - and as these energy powerhouses tend to weaken with age-new adverse effects can also develop the longer a patient takes statin drugs.
"The risk of adverse effects goes up as age goes up, and this helps explain why," said Golomb.
"This also helps explain why statins' benefits have not been found to exceed their risks in those over 70 or 75 years old, even those with heart disease."
High blood pressure and diabetes are linked to higher rates of mitochondrial problems, so these conditions are also clearly linked to a higher risk of statin complications, said the researchers.
The study is published in the on-line edition of American Journal of Cardiovascular Drugs.