Mode of action and adverse effects of lipid lowering drugs.

Serum lipids, cholesterol and triglycerides are incorporated into hydrophilic lipoproteins, which include chylomicrons, very low density lipoproteins (VLDL), intermediate density lipoproteins (IDL), low density lipoproteins (LDL) and high density lipoproteins (HDL). An elevated level of these lipoproteins, except for HDL, is the basis of all hyperlipidemias. However, only some of the lipoprotein fractions, particularly LDL and remnant particles, are potential risk factors for atherogenesis and subsequent cardiovascular disease. Several classes of pharmacological agents are currently available to increase the breakdown and reduce the synthesis of LDL and remnant factors. These include nicotinic acid and its analogs, fibric acid derivatives (e.g., clofibrate, gemfibrozil, bezafibrate), bile acid resins (e.g., cholestyramine), HMG-CoA reductase inhibitors (e.g., lovastatin, simvastatin, pravastatin) and probucol. Lipid lowering drugs of different classes have a synergistic effect on lipid metabolism and combination therapy is often used. Lipid lowering drugs are prescribed as long-term preventive therapy in apparently asymptomatic people. Several studies indicate that secondary prevention with lipid lowering drugs is cost-effective, particularly in patients with symptomatic coronary artery disease.