The active ingredient in a drug used to lower the amount of cholesterol in the blood and to prevent stroke and heart attack. It is also being studied in the treatment of cancer and other conditions. Pravastatin blocks an enzyme that helps make cholesterol in the body. It may also make tumor cells more sensitive to anticancer drugs. It is a type of HMG-CoA reductase inhibitor, a type of statin, and a type of chemosensitizer.