Lipitor (Pfizer), Atorvastatin (INN), is a member of the drug class known as statins, used for lowering blood cholesterol. It also stabilizes plaque and prevents strokes through anti-inflammatory and other mechanisms.
Atorvastatin calcium tablets are marketed by Pfizer under the trade name Lipitor, in tablets (10, 20, 40 or 80 mg) for oral administration. Tablets are white, elliptical, and film coated. Pfizer also packages the drug in combination with other drugs, such as is the case with its Caduet. In some countries, atorvastatin calcium is made in tablet form by generic drug makers under various brand names including Atoris, Atorlip, Lipvas, Sortis, Torvast, Torvacard, Totalip, and Tulip.
Atorvastatin inhibits HMG-CoA reductase, the rate-determining enzyme located in hepatic tissue that produces mevalonate, a small molecule used in the synthesis of cholesterol and other mevalonate derivatives. This lowers the amount of cholesterol produced which in turn lowers the total amount of LDL cholesterol.
Atorvastatin was first synthesized in 1985 by Bruce Roth while working at Parke-Davis Warner-Lambert Company (now Pfizer). With 2008 sales of US$12.4 billion, Lipitor was the top-selling branded pharmaceutical in the world. US patent protection is scheduled to expire in June 2011. However, Pfizer made an agreement with Ranbaxy Laboratories to delay the generic launch in the US until November 2011.
As with other statins, atorvastatin is a competitive inhibitor of HMG-CoA reductase. Unlike most others, however, it is a completely synthetic compound. HMG-CoA reductase catalyzes the reduction of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) to mevalonate, which is the rate-limiting step in hepatic cholesterol biosynthesis. Inhibition of the enzyme decreases ''de novo'' cholesterol synthesis, increasing expression of low-density lipoprotein receptors (LDL receptors) on hepatocytes. This increases LDL uptake by the hepatocytes, decreasing the amount of LDL-cholesterol in the blood. Like other statins, atorvastatin also reduces blood levels of triglycerides and slightly increases levels of HDL-cholesterol.
In clinical trials, the combination of ezetimibe (Zetia) and atorvastatin lowered cholesterol more effectively than Vytorin (ezetimibe + simvastatin).
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