Lovastatin and simvastatin are potent competitive inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase. Key inhibit the synthesis of cholesterol in cultured HepG23 cells, rat hepatocytes and in rats. The primary target organ of cholesterol synthesis inhibition by lovastatin and simvastatin is the liver. Lovastating and simvastatin lower levels of plasma cholesterol in rats, dogs and rabbits by inhibition the endogenous cholesterol synthesis and induction of LDL receptor in the liver.