Pfizer's Lipitor is a cholesterol-lowering drug that is used to treat high cholesterol and triglyceride levels in the blood. It is a synthetic lipase inhibitor that works by inhibiting the activity of an enzyme called HMG-CoA reductase, which is responsible for the production of cholesterol in the body. Lipitor is available in 10mg, 20mg, 40mg, and 80mg tablets.