Medication: Five Major Drug Classes

Currently, there are medications from five major classes of drugs to treat people with unhealthy lipid levels, as well as medications that combine drugs from the different classes. Each has a different mechanism of action and modifies blood lipids to varying degrees. The five classes are divided into the following categories:

• HMG-CoA reductase inhibitors (statins)
• Niacin
• Fibric acid derivatives
• Bile acid binding resins
• Cholesterol absorption inhibitors

HMG-CoA reductase inhibitors (statins) are medications that inhibit the rate at which cholesterol is formed in the body. This class of drug also can help draw cholesterol to the liver for excretion.

The most common side effects with these drugs are stomach upset, nausea/vomiting, headache, and dizziness. Liver function also should be periodically tested in people taking this medication.

Examples:

• Atorvastatin (Lipitor®)
• Fluvastatin (Lescol®)
• Lovastatin (Mevacor®)
• Pravastatin (Pravachol®)
• Rosuvastatin (Crestor®)
• Simvastatin (Zocor®)

Niacin has diverse actions affecting cholesterol formation. A primary effect appears to be that it decreases the production of triglycerides in the body, which might be the mechanism that allows this drug to decrease LDL levels. Nicotinic acid also raises HDL cholesterol levels via mechanisms not yet understood.

Some of the most common side effects of niacin drugs are flushing, hot flashes, itching, and headache. People who take niacin for a prolonged period of time, especially at high doses, should have periodic liver function tests.

Example:

• Nicotinic Acid (Nicobid®)

Fibric acid derivatives are medications whose exact mechanism of action is unknown. They are thought to reduce the formation and increase the breakdown of cholesterol and triglycerides.

The most common side effects of this class of drugs are heartburn and stomach pain. These side effects usually decrease over time. People who take this drug also should have periodic liver function tests.

Examples:

• Clofibrate (Atromid-S®)
• Fenofibrate(Tricor®)
• Gemfibrozil (Lopid®)

Bile acid binding resins are medications that bind with bile acids, preventing the intestine from recycling them. Sensing this decrease in bile acids, the liver responds by producing more and pulls cholesterol from the blood to do this.

The most common side effect of this drug is constipation.

Examples:

• Cholestyramine (Questran®)
• Colestipol (Colestid®)
• Colesevelam (Welchol®)

Cholesterol absorption inhibitors help reduce LDL levels by blocking absorption of cholesterol in the small intestine. These medications are used in conjunction with a program that includes eating a low-fat/low-cholesterol diet, exercising, and managing weight.

Common side effects of these medications include headache, dizziness, stomach upset, joint pain, and upper respiratory infections.

Example:

• Ezetimibe (Zetia®)

Combination Medication: Vytorin®

Vytorin, a combination medication that contains both simvastatin and ezetimibe, has been shown to lower LDL cholesterol to a greater extent than statin therapy alone. However, results from one trial showed that the combination drug was no more effective in reducing plaque buildup in the arteries than statin monotherapy. And results from another trial found that Vytorin did not reduce the risk of cardiovascular events in people who had heart valve problems any more than a placebo did.

Additional studies are needed to provide more information about the safety and efficacy of Vytorin.

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