The drugs compactin and lovastatin are fungal products. They are used to decrease the serum cholesterol level in patients with hypercholesterolemia. Compactin and lovastatin are competitive inhibitors of the enzyme HMG-CoA reductase and, therefore, reduce cholesterol synthesis. About 50%–60% decrease in serum cholesterol level has been reported by a combined use of these two drugs. HMG-CoA reductase activity is inhibited by bile acids; fasting also reduced the activity of this enzyme.

Regulation of cholesterol biosynthesis by HMG-CoA reductase is shown in Figure 10.4

Figure 10.4 Regulation of Cholesterol Biosynthesis by HMG-CoA Reductase