Cholesterol is a waxy, fat-like substance that occurs naturally in all parts of the body and that your body needs to function normally. It is present in cell walls or membranes everywhere in the body, including the brain, nerves, muscle, skin, liver, intestines, and heart. Your body uses cholesterol to produce many hormones, vitamin D, and the bile acids that help to digest fat. It takes only a small amount of cholesterol in the blood to meet these needs. If you have too much cholesterol in your bloodstream, the excess is deposited in arteries, including the coronary arteries, where it contributes to the narrowing and blockages that cause the signs and symptoms of heart disease.

Heart disease is caused by narrowing of the coronary arteries that feed the heart. Like any muscle, the heart needs a constant supply of oxygen and nutrients, which are carried to it by the blood in the coronary arteries. When the coronary arteries become narrowed or clogged by cholesterol and fat deposits--a process called atherosclerosis--and cannot supply enough blood to the heart, the result is coronary heart disease (CHD). If not enough oxygen-carrying blood reaches the heart, you may experience chest pain called angina. If the blood supply to a portion of the heart is completely cut off by total blockage of a coronary artery, the result is a heart attack. This is usually due to a sudden closure from a blood clot forming on top of a previous narrowing.

Heart disease patients and those at high risk for developing heart disease need to lower their LDL more than other people. As a result, medications are more often used by patients with heart disease and those at high risk than by those who do not have heart disease or who have a lower risk of developing it.

There are currently five statin drugs on the market in the United States: lovastatin, simvastatin, pravastatin, fluvastatin, and atorvastatin. The major effect of the statins is to lower LDL-cholesterol levels, and they lower LDL-cholesterol more than other types of drugs. Statins inhibit an enzyme, HMG- CoA reductase, that controls the rate of cholesterol production in the body. These drugs lower cholesterol by slowing down the production of cholesterol and by increasing the liver's ability to remove the LDL-cholesterol already in the blood. Statins were used to lower cholesterol levels in the 4S, CARE, and LIPID studies. The large reductions in total and LDL-cholesterol produced by these drugs resulted in large reductions in heart attacks and heart disease deaths. Thanks to their track record in these studies and their ability to lower LDL-cholesterol, statins have become the drugs most often prescribed when a person with heart disease needs a cholesterol- lowering medicine.