Atorvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor (a statin), is a lipid regulating drug with actions on plasma lipids. HMG-CoA reductase inhibitors reduce total cholesterol, low-density lipoprotein (LDL)-cholesterol and very-low-density lipoprotein (VLDL)-cholesterol concentrations in plasma. They also tend to reduce triglycerides and to increase high-density lipoprotein (HDL)-cholesterol concentrations. They are also considered to exert their hypocholesterolaemic action by stimulating an increase in LDL-receptors on hepatocyte membranes thereby increasing the clearance of LDL from the circulation.
Atorvastatin is rapidly absorbed from the gastro-intestinal tract. It has low absolute bioavailability of about 12% due to presystemic clearance in the gastro-intestinal mucosa and/or first-pass metabolism in the liver, its primary site of action. Atorvastatin is metabolised by the cytochrome P450 isoenzyme CYP3A4 to a number of compounds which are also active inhibitors of HMG-CoA reductase. The mean plasma elimination half-life of Atorvastatin is about 14 hours although the half-life of inhibitory activity for HMG-CoA reductase is approximately 20 to 30 hours due to the contribution of the active metabolites. It is 98% bound to plasma proteins. Atorvastatin is excreted as metabolites, primarily in the bile.
Atorvastatin is used to reduce LDL-cholesterol, apolipoprotein B, and triglycerides, and to increase HDL-cholesterol in the treatment of hyperlipidaemias including hypercholesterolaemias and combined (mixed) hyperlipidaemia (type IIa or IIb hyperlipoproteinaemias), hypertriglyceridaemia (type IV), and dysbetalipoproteinaemia (type III). Atorvastatin can also be effective as adjunctive therapy in patients with homozygous familial hypercholesterolaemia who have some LDL-receptor function.