Making lifestyle changes and modifying diet - as most doctors advise to lower cholesterol levels - isn't enough for some people, who may be genetically predisposed to high blood cholesterol. For these people, powerful cholesterol-lowering medications can help

These medications are usually prescribed for patients who have coronary artery disease and high cholesterol, but recent studies have also shown that they can benefit patients who have coronary artery disease and normal cholesterol levels. The research has shown that medication, in both instances, decreases the risk of heart attacks and death.

Cholesterol isn't the only factor that puts people at risk for heart disease, but it is a major culprit. Eating foods that are high in saturated fats, trigylcerides and cholesterol - which is a type of fat manufactured by the liver - causes arteriosclerosis or hardening of the arteries. These fats build up in the walls of the arteries, slowing or blocking the flow of blood to the heart.

The National Cholesterol Education Program estimates that as many as 13 million Americans take some form of cholesterol-lowering drug therapy.

What are the most commonly prescribed cholesterol-lowering drugs?

The most commonly prescribed cholesterol drugs nowadays are in the statin family, which includes Mevacor (lovastatin), Lescol (fluvastatin), Pravachol (pravastatin), Zocor (simvastatin), and Lipitor (atorvastatin). Statins are fast becoming the most widely prescribed drugs to lower cholesterol. Depending on the drug and dosage, statins can lower LDL cholesterol (known as the "bad cholesterol") as much as 60 percent.

A study published in the medical journal Circulation in 1998 found that lowering a person's cholesterol may be beneficial - even if his or her cholesterol is average or low. The study examined 500 patients with atherosclerosis and average cholesterol levels who were given pravastatin. The research found that for every 10-percentage points cholesterol was reduced, the risk of heart disease dropped by 15 percent.

In 1997, the Air Force/Texas Coronary Atherosclerosis Prevention Study showed that lovastatin helped prevent a first heart attack or unstable angina in men and women with average cholesterol levels but with below-average HDL - or "good" cholesterol.

Taken in tablet or capsule form, statins (also known as HMG-CoA reductase inhibitors) work by blocking a substance your liver needs to manufacture cholesterol. That not only depletes cholesterol in your liver cells, it causes the cells to remove cholesterol from circulating blood as well. Statins may also help your body reabsorb cholesterol from plaques, slowly unplugging blood vessels.

Statins are usually taken in a single dose at the evening meal or at bedtime. It is important that these medications be taken in the evening to take advantage of the fact that the body makes more cholesterol at night than during the day.

Statins are well tolerated by most patients, and serious side effects are rare. Patients may experience an upset stomach, gas, constipation, and abdominal pain or cramps. These symptoms usually are mild or moderate and generally go away as their bodies adjust. Patients rarely develop abnormalities in blood tests of the liver. However, most manufacturers of statins recommend an initial evaluation of simple blood tests that indicate liver damage and periodic follow-up checks.

What other types of treatment are available?

Medical experts caution about the use of cholesterol-lowering supplements sold over the counter. For one thing, the effectiveness of these supplements is dubious. For another, supplements won't work unless you make dietary changes.

Other types of cholesterol-reducing treatments:

Niacin (nicontinic acid) in the only dietary supplement that has been proven to lower LDL cholesterol and raise HDL cholesterol. However, the dose needed for treatment is about 100 times more than the Recommended Daily Allowance for niacin and can be potentially toxic. As a result, the drug must be taken under a doctor's care.

Resins have been used as cholesterol-lowering drugs for about two decades. Questran (cholestyramine) and Colestid (colestipol) lower cholesterol by binding with bile acids in your intestinal tract and preventing their recycling through the liver. Bile acids are made in your liver from cholesterol and are needed for food digestion.

Fibrates (or fibric acid derivatives) are used mainly to lower triglycerides. The triglyceride-lowering effect of these drugs, Lopid (gemfibrozil) and Trico (fenofibrate), is also associated with an increase in HDL levels.