Statins and myopathy
Simvastatin (Zocor®) belongs to a class of cholesterol-lowering medicines called statins that when used together with a heart healthy .diet and exercise, reduce the risk of heart attack, stroke and death from heart diseases. Simvastatin is one of the most commonly prescribed statins. Although statins are effective and generally safe, some persons who take them experience myopathy, a condition that causes muscular weakness, pain and cramps. Myopathy can affect 5 -10% of those who take statins.
Although all statins can cause myopathy, simvastatin, especially in high doses, is the one that most probably causes it. Many genetic and non-genetic factors can affect the myopathy generated by statins. The most studied is the genetic variant on the gene SLCO1B1 that is linked to myopathy on taking simvastatin. SLCO1B1 encodes a protein that helps the liver absorb statins. When this protein does not function adequately, the simvastatin levels in the blood and muscle tissue can become very high.
Risk factors such as age, gender, ethnicity, body mass index, other health conditions and medicines that are taken at the same time can affect how a person responds to simvastatin.
- The side effects frequently related to statin use are:
- Digestive: constipation, bloating, gasses, nausea, vomiting, dyspepsia, diarrhea, abdominal pain, anorexia
- Neurologic: insomnia, fatigue, headaches, depression, memory loss, blurry vision, tinnitus
- Dermatologic: hives, alopecia
- ORL: rhinosinusitis, nasopharyngitis, flu-like syndrome
- General: transitory raise of transaminases (suspend treatment if it is prolonged or more than 3 times the normal value) and creatine kinase (suspend), myalgia, myositis, and rhabdomyolysis. associated occasionally with renal insufficiency (suspend). Thrombocytopenia, chest pain, peripheral edema. Hyperglycemia and hypoglycemia.
Liver and muscular functions should be monitored before and every 4 -6 weeks during the first year of treatment, and afterwards periodically. Myopathy symptoms should be watched. Precautions must be taken if there is a history of alcohol abuse or hepatopathy. The risk of diabetes mellitus can increase in patients with a risk of developing said disease.
Gene or region studied