Simvastatin is indicated for the following cases-

• Hyperlipidemia
• Prevention of Cardiovascular diseases (myocardial infarction, stroke, angina etc.)
• Coronary heart diseases

Hyperlipidemia

Prevention of Cardiovascular diseases

Coronary Heart Disease

• The typical daily dosage range is 5 to 40 mg. 
• SIMVASTATIN can be started concurrently with diet in patients with coronary heart disease or at high risk of coronary heart disease. The normal starting dose is 10 to 20 mg taken once a day in the evening. The suggested initial dose for patients at high risk for a coronary heart disease event due to existing coronary heart disease, diabetes, peripheral artery disease, history of stroke, or other cerebrovascular disease is 40 mg/day. Lipid tests should be done after 4 weeks of medication and then on a regular basis after that.
• Due to the increased risk of myopathy, including rhabdomyolysis, particularly during the first year of treatment, use of the 80-mg dose of SIMVASTATIN should be restricted to patients who have been taking simvastatin 80 mg chronically (e.g., for 12 months or more) without evidence of muscle toxicity.
• Caution should be exercised when SIMVASTATIN is administered to patients with severe renal impairment; such patients should be started at 5 mg/day and be closely monitored

The most commonly reported adverse reactions (incidence ≥5%) in simvastatin are-

• gastrointestinal disorders (diarrhea, vomiting etc.)
• myalgia and arthralgia
• upper respiratory infections (nasopharyngitis)
• headache
• abdominal pain
• constipation
• nausea 

Nausea

Myalgia

Nasopharyngitis

Diarrhea

• Myopathy/Rhabdomyolysis: Simvastatin occasionally causes myopathy manifested as muscle pain, tenderness or weakness with creatine kinase (CK) above ten times the upper limit of normal. Myopathy sometimes takes the form of rhabdomyolysis with or without acute renal failure secondary to myoglobinuria, and rare fatalities have occurred. Predisposing factors for myopathy include advanced age (≥65 years), female gender, uncontrolled hypothyroidism, and renal impairment.
• The risk of myopathy, including rhabdomyolysis, is dose related.
• The risk of myopathy, including rhabdomyolysis, is greater in patients on simvastatin 80 mg compared with other statin therapies with similar or greater LDL-C-lowering efficacy and compared with lower doses of simvastatin.
• All patients starting therapy with simvastatin, or whose dose of simvastatin is being increased, should be advised of the risk of myopathy, including rhabdomyolysis, and told to report promptly any unexplained muscle pain, tenderness or weakness. Simvastatin therapy should be discontinued immediately if myopathy is diagnosed or suspected.