Lovastatin, an antilipemic agent produced by fermentation of Aspergillus terreus, is the first of a class of lipid-lowering agents known as the hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors. HMG-CoA catalyzes the conversion of HMG-CoA to mevalonic acid, the rate-limiting step of cholesterol biosynthesis. Lovastatin, like simvastin, is a prodrug. These prodrugs are converted to their active form by in vivo hydrolysis of the lactone ring. The hydrolyzed lactone ring resembles the tetrahedral reaction intermediate produced by HMG-CoA reductase and the bicyclic portions of these compounds bind to the coenzyme A site of the enzyme. The active drug concentrates in the liver during first-pass circulation. Cholesterol biosynthesis accounts for approximately 80% of cholesterol in the body; thus, inhibiting this process can significantly lower cholesterol levels. Lovastatin is used to treat hypercholesterolemia, to slow coronary atherosclerosis, and to prevent myocardial infarction and stroke.