Cholesterol is a naturally occurring fat that is critical for good health. The liver makes cholesterol for the body, but cholesterol can also enter the body through dietary sources. Too much cholesterol can promote atherosclerosis and coronary artery disease. Medicines that lower the bad cholesterol, also called LDL, and/or raise the good cholesterol, HDL, are therefore used by millions of patients to control cholesterol levels and decrease the risk of coronary artery disease. Cholesterol-lowering drugs include statins, bile acid resins, niacin, fibric acid derivatives and cholesterol absorption inhibitors. Most of these drugs are well tolerated, with reasonable safety profiles.
Statins
Statins are among the most widely used drugs worldwide. They lower LDL by blocking production of cholesterol in the liver. Generally, statins are well tolerated; common side effects include headache, constipation, diarrhea, stomach pain and muscle pain.
Statins may cause mild enzyme increases in some patients. Generally these changes are benign and transient, and patients continue their treatment. However, serious enzyme elevations, if left unchecked, may lead to permanent liver damage. For this reason, patients on statins should have their liver enzymes checked periodically during their first year of treatment. Statins should not be given to patients with active or chronic liver disease.
In rare cases, statins may cause rhabdomyolysis or severe muscle breakdown. If not treated, this can lead to kidney failure and death. One statin, Baycol, was withdrawn from the market in 2001 after being implicated in more than 60 deaths due to rhabdomyolysis.
Bile Acid Resins
Bile acid resins work by binding to bile in the digestive tract. As the resin eliminates bile, the liver takes in more cholesterol from the blood in order to produce more bile. As a result, LDL levels drop. Examples of resins include Questran, Colestid and WelChol.
These drugs are very safe because they stay in the digestive tract and don't get absorbed into other body tissues. However, they may cause gastrointestinal problems such as constipation, heartburn and gas. Some patients find these side effects too bothersome to continue therapy. Over time, bile acid resins may also contribute to deficiencies of vitamins A, D, E, and K. In such cases, vitamin supplements may be necessary.
Niacin
Niacin, or nicotinic acid, is a B vitamin. Niacin raises HDL and lowers LDL, and is often used in combination with statins. Its most common side effects are flushing of the face and neck, headache, dizziness and itching. These usually occur within minutes of taking niacin and may last for minutes or hours. Over time, patients may become tolerant to these side effects; however, many patients discontinue therapy. Liver problems may also develop in some patients on niacin, although they generally disappear after therapy is discontinued. An extended-release form of niacin, called Niaspan, may have fewer side effects. People with chronic liver disease should not use any form of niacin.
Fibrates
Fibrates, also called fibric acid derivatives, lower cholesterol by reducing the amount of triglycerides. They also increase HDL levels. Some examples of fibrates include fenofibrate and gemfibrozil. Side effects may include gastrointestinal discomfort, aching muscles and sensitivity to sunlight. Fibrates may also cause gallstones in susceptible patients, so people with gallbladder problems should not use these drugs.
Cholesterol Absorption Inhibitors
Zetia is one of a newer class of cholesterol-lowering drugs. Unlike statins, which block the synthesis of cholesterol, Zetia works by blocking absorption of cholesterol from the food we eat. It is often used in combination with a statin.
The most common side effects of Zetia are minor, and include respiratory tract infections, joint pain, sinus infection, diarrhea and pain in the arms or legs. As with statins, Zetia may also cause severe muscle breakdown, or rhabdomyolysis, in very rare cases.
Conclusion
As with any medicine, side effects can occur with cholesterol-lowering drugs. However, most patients tolerate these medicines very well. If side effects do occur, they are usually minor and can easily be treated. Patients who experience more serious or unexplained side effects should contact their health-care provider immediately.
