[Mechanism of action of hypolipemic drugs]

Hypolipemic drugs decrease the plasmatic concentrations of atherogenic lipoproteins, especially LDL. Two main drug families are used: fibrates and inhibitors of HMG CoA reductase. Fibrates act essentially as an activator of lipoprotein lipase and by increasing the catabolism of triglyceride rich lipoproteins. Further, they have a slight and non specific inhibitory effect on HMG CoA reductase activity, while, the new drug family of "statines" have a high, specific inhibitory effect on this essential enzyme of the cholesterol synthesis pathway. This enzymatic inhibition decreases the cholesterol synthesis and increases the activity of the hepatic LDL receptors, which are in charge of LDL elimination from the body. Resins entrap biliary salts and increase the cholesterol loss in feces and induce an over expression of the LDL receptors of the hepatocytes. Probucol inhibits atherogenesis by decreasing both LDL and HDL cholesterol and delaying LDL oxidative processing which is now believed to be one of the major factors of atherogenicity.