Atorvastatin Calcium Salt is a selective and competitive HMGCR (HMG-CoA reductase) inhibitor, the rate-controlling enzyme of the mevalonate pathway, the metabolic pathway that produces cholesterol and other isoprenoids. Inhibition of HMG-CoA reductase results in a drastic reduction in the production of cholesterol and other isoprenoids. Competitive inhibitors of the reductase are believed to induce the expression of LDL (Low Density Lipoprotein) receptors in the liver, which in turn increases the catabolism of plasma LDL and lowers the plasma concentration of cholesterol.