Overview
11 DESCRIPTION Simvastatin is a prodrug of 3-hydoroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor that is derived synthetically from a fermentation product of Aspergillus terreus . Simvastatin is butanoic acid, 2,2-dimethyl-,1,2,3,7,8,8a-hexahydro-3,7-dimethyl-8-[2-(tetrahydro-4-hydroxy-6-oxo-2 H -pyran-2-yl)-ethyl]-1-naphthalenyl ester, [1 S -[1α,3α,7β,8β(2 S* ,4 S* ),-8aβ]].
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Simvastatin is a prodrug and is hydrolyzed to its active β-hydroxyacid form, simvastatin acid, after administration. Simvastatin acid and its metabolites are inhibitors of HMG-CoA reductase, the rate-limiting enzyme that converts HMG-CoA to mevalonate, a precursor of cholesterol. 12.2 Pharmacodynamics Inhibition of HMG-CoA reductase by simvastatin acid accelerates the expression of LDL-receptors, followed by the uptake of LDL-C from blood to the liver, leading to a decrease in plasma LDL-C and total cholesterol. Sustained inhibition of cholesterol synthesis in the liver also decreases levels of very-low-density lipoproteins. The maximum LDL-C reduction of simvastatin is usually achieved by 4 weeks and is maintained after that 12.
Indications
- 1 INDICATIONS AND USAGE Simvastatin tablets USP are indicated: To reduce the risk of total mortality by reducing risk of coronary heart disease death, non-fatal myocardial infarction and stroke, and the need for coronary and non-coronary revascularization procedures in adults with established coronary heart disease, cerebrovascular disease, peripheral vascular disease, and/or diabetes, who are at high risk of coronary heart disease events. As an adjunct to diet to reduce low-density lipoprotein cholesterol (LDL-C): In adults with primary hyperlipidemia.
Common Doses
- 40 mg
- 80 mg
- 20 mg
- 10 mg
Dosage
2 DOSAGE AND ADMINISTRATION Important Dosage and Administration Information : ( 1 ) Take simvastatin tablets USP orally once daily in the evening. Maximum recommended dosage is simvastatin tablets USP 40 mg once daily. An 80 mg daily dosage of simvastatin tablets USP is restricted to patients who have been taking simvastatin tablets USP 80 mg daily chronically (e.g., for 12 months or more) without evidence of muscle toxicity.
Contraindications
- 4 CONTRAINDICATIONS Simvastatin is contraindicated in the following conditions: Concomitant use of strong CYP3A4 inhibitors (select azole anti-fungals, macrolide antibiotics, anti-viral medications, and nefazodone) [see DRUG INTERACTIONS ( 7.1 )]. Concomitant use of cyclosporine, danazol or gemfibrozil [see DRUG INTERACTIONS ( 7.1 )]. Acute liver failure or decompensated cirrhosis [see WARNINGS AND PRECAUTIONS ( 5.3 )] Hypersensitivity to simvastatin or any excipients in simvastatin tablets USP.
Side Effects
- 6 ADVERSE REACTIONS The following important adverse reactions are described below and elsewhere in the labeling: Myopathy and Rhabdomyolysis [see WARNINGS AND PRECAUTIONS ( 5.1 )] Immune-Mediated Necrotizing Myopathy [see WARNINGS AND PRECAUTIONS ( 5.2 )] Hepatic Dysfunction [see WARNINGS AND PRECAUTIONS ( 5.3 )] Increases in HbA1c and Fasting Serum Glucose Levels [see WARNINGS AND PRECAUTIONS ( 5.4 )] Most common adverse reactions (incidence ≥5%) are: upper respiratory infection, headache, abdominal pain, constipation, and nausea. ( 6.
Interactions
- 7 DRUG INTERACTIONS See full prescribing information for details regarding concomitant use of simvastatin with other drugs or grapefruit juice that increase the risk of myopathy and rhabdomyolysis. ( 2.5 , 7.1 ) Coumarin Anticoagulants: Obtain INR before simvastatin initiation and monitor INR during simvastatin dosage initiation or adjustment. ( 7.2 ) Digoxin: During simvastatin initiation, monitor digoxin levels. ( 7.2 ) 7.1 Drug Interactions that Increase the Risk of Myopathy and Rhabdomyolysis with Simvastatin Simvastatin is a substrate of CYP3A4 and of the transport protein OATP1B1.