Lovastatin

Lovastatin is a lactone which is readily hydrolyzed in vivo to the corresponding β-hydroxyacid and strong inhibitor of HMG-CoA reductase, a hepatic microsomal enzyme which catalyzes the conversion of HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) to mevalonate, an early rate-limiting step in cholesterol biosynthesis. At therapeutic lovastatin doses, HMG-CoA reductase is not completely blocked, thereby allowing biologically necessary amounts of mevalonate to be available. Because the conversion of HMG-CoA to mevalonate is an early step in the biosynthetic pathway for cholesterol, therapy with lovastatin would not be expected to cause an accumulation of potentially toxic sterols.

Lovastatin acts primarily in the liver, where decreased hepatic cholesterol concentrations stimulate the upregulation of hepatic low density lipoprotein (LDL) receptors which increase hepatic uptake of LDL. Lovastatin also inhibits hepatic synthesis of very low density lipoprotein (VLDL). The overall effect is a decrease in plasma LDL and VLDL and a significant reduction in the risk of development of CVD and all-cause mortality.

A significant effect on LDL-C reduction was seen within 2 weeks of initiation of lovastatin, and the maximum therapeutic response occurred within 4-6 weeks. The response was maintained during continuation of therapy. Single daily doses given in the evening were more effective than the same dose given in the morning, perhaps because cholesterol is synthesized mainly at night. When therapy with lovastatin is stopped, total cholesterol has been shown to return to pre-treatment levels.

In vitro and in vivo animal studies also demonstrate that lovastatin exerts vasculoprotective effects independent of its lipid-lowering properties, also known as the pleiotropic effects of statins. This includes improvement in endothelial function, enhanced stability of atherosclerotic plaques, reduced oxidative stress and inflammation, and inhibition of the thrombogenic response.

Statins have also been found to bind allosterically to β2 integrin function-associated antigen-1 (LFA-1), which plays an important role in leukocyte trafficking and in T cell activation.

Lovastatin has been reported to have beneficial effects on certain cancers. This includes a multi-factorial stress-triggered cell death (apoptosis) and DNA degradation response in breast cancer cells. It has also been shown to inhibit histone deacetylase 2 (HDAC2) activity and increase the accumulation of acetylated histone-H3 and the expression of p21(WAF/CIP) in human cancer cells, suggesting that statins might serve as novel HDAC inhibitors for cancer therapy and chemoprevention.