Simvastatin CAS:79902-63-9 Simvastatin is a hypolipidemic drug used to treat hypercholesterolemia. It is competitive inhibitor of HMG-CoA reductase, the enzyme catalysing the early rate-limiting step in cholesterol biosynthesis, i.e. conversion of HMG-CoA to mevalonate .Successfully used in the treatment of coronary heart diseases.