A cholesterol lowering drug and a competitive inhibitor of HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase (IC₅₀ = 154 nM) a rate limiting enzyme in cholesterol synthesis. Blocks the production of mevalonate, a critical compound in the production of cholesterol and isoprenoids. In addition to inhibiting cholesterol synthesis, atorvastatin reduces the production of low-density lipoprotein (LDL).