A synthetic lipid-lowering agent. Atorvastatin competitively inhibits hepatic hydroxymethyl-glutaryl coenzyme A (HMG-CoA) reductase, the enzyme which catalyzes the conversion of HMG-CoA to mevalonate, a key step in cholesterol synthesis. Atorvastatin also increases the number of LDL receptors on hepatic cell surfaces to enhance uptake and catabolism of LDL and reduces LDL production and the number of LDL particles. This agent lowers plasma cholesterol and lipoprotein levels and modulates immune responses by suppressing MHC II (major histocompatibility complex II) on interferon gamma-stimulated, antigen-presenting cells such as human vascular endothelial cells. (NCI04) [from NCI]