Simvastatin, is a cholesterol lowering agent that is derived synthetically from a fermentation product of Aspergillus terreus. After oral ingestion, Simvastatin, which is an inactive lactone, is hydrolysed to the corresponding beta-hydroxyacid form. This is an inhibitor of 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG Co A) reductase. This enzyme catalyses the conversion of HMG Co A to mevalonate, which is an early and rate-limiting step in the biosynthesis of cholesterol.
Simvastatin has been shown to reduce both normal and elevated LDL cholesterol concentration. The mechanism of the LDL-lowering effect of Simvastatin may involve both reduction of very low density lipoprotein (VLDL) cholesterol concentration and induction of the LDL receptor leading to reduced production and/or increased catabolism of LDL cholesterol. Apolipoprotein B also falls substantially during treatment with Simvastatin. In addition, Simvastatin modestly reduces VLDL cholesterol and plasma triglycerides and can produce increase of variable magnitude in HDL cholesterol.