Cholesterol is a soft, fat-like, waxy substance found in the bloodstream and cells of the body. It functions as a vital component in hormone production, cell membrane formation and other bodily functions. Cholesterol poses no problem until levels become too high, and then it is a major risk factor for coronary artery disease and stroke. Although a healthy diet and physical activity improve cholesterol levels, medications are often prescribed to lower cholesterol. These medications come in a variety of classes with different mechanisms of action.
Cholesterol
In looking at the different classes of cholesterol it is important to know the two types of cholesterol as well as have an understanding of triglycerides. HDL (high density lipoprotein) is called "good" cholesterol because it clears cholesterol from the arteries, while LDL is "bad" cholesterol that accumulates in the arteries causing blockage and ultimately a heart attack or stroke. Triglycerides are a type of fat that provides energy to the body's cells. Like cholesterol, they are a normal part of the body but become a problem when in excess leading to an increased risk of heart disease.
Statins
Statins are the most common cholesterol medication and function in the liver to decrease LDL and triglyceride levels while slightly increasing HDL levels. Statins are popular and show high patient acceptance because they are easy to administer, have relatively few side effects and drug interactions, as indicated by the American Heart Association. Common side effects include constipation, nausea, diarrhea, and abdominal and muscle pain.
Resins
Resins function solely to decrease LDL levels. Resins bind and reduce the amount of bile acids in the body. When bile acid levels are reduced, the liver converts cholesterol into bile acid, thus lowering cholesterol levels. Resins are available in capsule form or as an oral powder to be mixed with water, applesauce or other non-carbonated liquids. Common side effects include heartburn, constipation, indigestion, flatulence and nausea.
Cholesterol Absorption Inhibitors
Cholesterol absorption inhibitors work mainly to decrease LDL levels, while slightly decreasing triglycerides and increasing HDL. Ezetimibe is the only approved cholesterol absorption inhibitor medication available as of early 2010. It works by decreasing intestinal absorption of cholesterol in foods. Common side effects include fatigue and stomach pain.
Fibrates
Fibrates are used to decrease triglycerides and increase HDL without affecting LDL levels. Fibrates function in the liver to clear triglycerides faster and to decrease production of VLDL, which carries triglycerides in the blood. Common side effects include headache, constipation or diarrhea, dizziness and abdominal pain.
Niacin (Nicotinic Acid or Vitamin B3)
Niacin is available via prescription or as an unregulated non-prescription dietary supplement. The mechanism of action by which niacin lowers cholesterol and triglyceride levels is unknown. Niacin is administered orally in tablet form, and common side effects include facial flushing, headache, upset stomach, heartburn and diarrhea.
Combination
Health care providers often prescribe multiple cholesterol-lowering medications to combat high cholesterol levels, such as statin therapy combined with niacin. Drug makers have combined several different medications into one to provide a more effective cholesterol-lowering medication. For instance, a cholesterol absorption inhibitor combined with a statin function to reduce LDL and raise HDL levels. Statin and niacin combined medications are prescribed to reduce LDL and triglycerides while increasing HDL "good" cholesterol levels.
