Merck’s cholesterol-lowering drug Zocor (generic: simvastatin) has recently been linked to muscle damage, myopathy, rhabdomyolysis and kidney failure. The U.S. Food & Drug Administration (FDA) is recommending limiting the use of the highest approved dose of Zocor because of these potential side effects. Doctors and patients are being advised to carefully weigh the risks vs. benefits of taking Zocor before prescribing.
Manufactured and marketed by Merck & Co., Zocor is an FDA-approved prescription medication used to lower cholesterol and triglycerides (types of fat) in the blood. Zocor is in a group of drugs called HMG CoA reductase inhibitors that reduce levels of bad cholesterol (low-density lipoprotein, or LDL) and triglycerides in the blood, while increasing levels of “good” cholesterol (high-density lipoprotein, or HDL). In addition to being prescribed to treat high cholesterol, Zocor is also commonly used to lower the risk of stroke, heart attack and other complications in patients with diabetes, coronary heart disease and other risk factors.
Side Effects of Zocor
Despite its relative effectiveness at treating high cholesterol, high doses of Zocor have recently been linked to a number of potentially life-threatening side effects. Patients prescribed the 80 mg. dose of Zocor have an increased risk of developing:
- muscle damage
- kidney damage
- kidney failure
Myopathy is a muscular disease in which the muscle fibers do not function, resulting in severe muscular weakness. The primary defect of myopathy is within the muscle, as opposed to the nerves or elsewhere. Signs and symptoms of Zocor-induced myopathy include:
- muscle weakness
- tetany (involuntary contraction of the muscles)
In a clinical trial where 41,050 patients were treated with Zocor – the majority of which were treated for at least 4 years – the incidence of myopathy was approximately:
- 0.02% at 20 mg./day
- 0.08% at 40 mg./day
- 0.53% at 80 mg./day
Additionally, the FDA analyzed results of the SEARCH trial, which evaluated the number of cardiovascular events in 6,031 patients taking the 80 mg. dose of Zocor compared to 6,033 patients taking 20 mg. of Zocor. The cumulative results showed a significantly higher percentage of myopathy in the 80 mg. group.
Zocor Kidney Failure
Kidney failure (also commonly referred to as renal failure) is the sudden loss of the ability of the kidneys to remove waste and concentrate urine without losing electrolytes. The disease can occur from an acute situation, chronic problems or from medications like Zocor. Signs and symptoms of Zocor-induced kidney failure include:
- weight loss
- nocturnal urination
- more or less frequent urination habits
- bone damage
- muscle cramps
- abnormal heart rhythms
- muscle paralysis
- swelling of the legs, ankles, feet or hands
- low blood pressure
Rhabdomyolysis refers to the rapid breakdown of skeletal muscle, which results in the release of muscle fiber contents (myoglobin) into the blood stream. Myoglobin is harmful to the kidneys and often results in severe kidney damage and / or kidney failure. The diagnosis of rhabdomyolysis is typically identified with the help of blood tests and urinalysis. Signs and symptoms of Zocor-induced rhabdomyolysis depend on the severity of the condition, and may include:
- muscle pain
- tenderness, weakness or swelling of the affected muscles
- low blood pressure
- abnormal heart rate and rhythm
Zocor FDA Press Release
On June 8, 2011, the U.S. Food & Drug Administration (FDA) issued a press release recommending limiting the use of the highest approved dose of Zocor (simvastatin 80 mg) because of an increased risk of muscle damage. Patients taking the 80 mg dose have an increased risk of myopathy and other dangerous side effects compared to patients taking lower doses of the drug or other drugs in the same class.
“This risk appears to be higher during the first year of treatment, is often the result of interactions with certain medicines, and is frequently associated with a genetic predisposition toward simvastatin-related myopathy. The most serious form of myopathy, called rhabdomyolysis, can damage the kidneys and lead to kidney failure which can be fatal.”
The FDA is requiring changes to Zocor labels to include new information about drug interactions and dose limitations. The administration is recommending that Zocor 80 mg should not be started in new patients, including patients already taking lower doses of the drug.