Cholesterol-reducing drugs are medicines that lower the amount of cholesterol (a fat-like substance) in the blood.
Purpose
Cholesterol is a chemical that can both benefit and harm the body. On the good side, cholesterol plays important roles in the structure of cells and in the production of hormones. But too much cholesterol in the blood can lead to heart and blood vessel disease. To complicate matters, not all cholesterol contributes to heart and blood vessel problems. One type, called high-density lipoprotein (HDL) cholesterol, or "good cholesterol," actually lowers the risk of these problems. The other type, low-density lipoprotein (LDL) cholesterol, or "bad cholesterol," is the type that threatens people's health. The names reflect the way cholesterol moves through the body. To travel through the bloodstream, cholesterol must attach itself to a protein. The combination of a protein and a fatty substance like cholesterol is called a lipoprotein.
Many factors may contribute to the fact that some people have higher cholesterol levels than others. A diet high in certain types of fats is one factor. Medical problems such as poorly controlled diabetes, an under active thyroid gland, an overactive pituitary gland, liver disease or kidney failure also may cause high cholesterol levels. And some people have inherited disorders that prevent their bodies from properly using and eliminating fats. This allows cholesterol to build up in the blood.
Treatment for high cholesterol levels usually begins with changes in daily habits. By losing weight, stopping smoking, exercising more and reducing the amount of fat and cholesterol in the diet, many people can bring their cholesterol levels down to acceptable levels. However, some may need to use cholesterol-reducing drugs to reduce their risk of health problems.
Description
There are four different classes of cholesterol lowering drugs:
Bile acid sequesterants are drugs that act by binding with the bile produced by the liver. Bile helps the digestion and absorption of fats in the intestine. By blocking the digestion of fats, bile acid sequesterants prevent the formation of cholesterol. Drugs in this class include: cholestyramine (Questran); colestipol (Colestid); and colesevalam (Welchol).
HMG-CoA inhibitors, often called "statins," are drugs that block an enzyme called "3-hydroxy-3-methylglutaryl-coenzyme A reductase." This blocks one of the steps in converting fat to cholesterol. These are the most effective cholesterol lowering agents available. Drugs in this group include: atorvastatin (Lipitor); cerivastatin (Baycol); fluvastatin (Lescol); lovastatin (Mevacor); pravastatin (Pravachol); and simvastatin (Zocor).
Fibric acid derivatives include clofibrate (Atromid-S); gemfibrozil (Lopid); and fenofibrate (Tricor). Although these drugs are less effective than the statins at lowering total cholesterol, they may be able to lower the low-density lipoprotein (LDL) cholesterol while raising the high-density lipoprotein (HDL) cholesterol. Their exact mechanism of action is believed to be associated with inhibition of lipoprotein lipase activity.
Niacin, vitamin B-3, is also effective in lowering cholesterol levels. Although the normal vitamin dose of niacin is only 20 mg, the dose required to reduce cholesterol levels is at least 500 mg each day. The mechanism of action of niacin in cholesterol reduction is associated with the inhibition of VLDL secretion in the blood-stream.
Recommended dosage
The recommended dosage depends on the type of cholesterol-reducing drug used. The prescribing physician or the pharmacist who filled the prescription can advise about the correct dosage.
Cholesterol-reducing drugs should be taken exactly as directed and doses should not be missed. Double doses should not be taken to make up for a missed dose.
Physicians may prescribe a combination of cholesterol-reducing drugs, such as pravastatin and colestipol. Following the directions for how and when to take the drugs is very important. The medicine may not work properly if both drugs are taken at the same time of day.
Niacin should not be taken at the same time as an HMG-CoA inhibitor, as this combination may cause severe muscle problems. If niacin is taken in an over-the counter form, both the prescribing physician and pharmacist should be informed. There are no problems when the niacin is taken in normal doses as a vitamin.
The prescription should not be stopped without first checking with the physician who prescribed it. Cholesterol levels may increase when the medicine is stopped, and the physician may prescribe a special diet to make this less likely.
Precautions
Seeing a physician regularly while taking cholesterol-reducing drugs is important. The physician will check to make sure the medicine is working as it should and will decide whether it is still needed. Blood tests and other medical tests may be ordered to help the physician monitor the drug's effectiveness and check for side effects.
For most people, cholesterol-reducing drugs are just one part of a whole program for lowering cholesterol levels. Other important elements of the program may include weight loss, exercise, special diets and changes in other habits. The medication should never be viewed as a substitute for other measures ordered by the physician. Cholesterol-reducing drugs will not cure problems that cause high cholesterol; they will only help control cholesterol levels.
People over 60 years of age may be unusually sensitive to the effects of some cholesterol-reducing drugs. This may increase the chance of side effects.
Anyone who is taking an HMG-CoA reductase inhibitor should notify the health care professional in charge before having any surgical or dental procedures or receiving emergency treatment.
Special conditions
People who have certain medical conditions or who are taking certain other medications may have problems if they take cholesterol-reducing drugs. Before taking these drugs, the prescribing physician should be informed of any of the following conditions:
ALLERGIES. Anyone who has had unusual reactions to cholesterol-reducing drugs in the past should inform the prescribing physician before taking the drugs again. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.
PREGNANCY. Studies of laboratory animals have shown that giving high doses of gemfibrozil during pregnancy increases the risk of birth defects and other problems, including death of the unborn baby. The effects of this drug have not been studied in pregnant women. Women who are pregnant or who may become pregnant should check with their physicians before using gemfibrozil.
Cholesterol-reducing drugs in the group known as HMG-CoA reductase inhibitors (such as lovastatin, fluvastatin, pravastatin and simvastatin) should not be taken by women who are pregnant or who plan to become pregnant soon. By blocking the production of cholesterol, these drugs prevent a fetus from developing properly. Women who are able to bear children should use an effective birth control method while taking these drugs. Any woman who becomes pregnant while taking these drugs should check with her physician immediately.
Cholestyramine and colestipol will not directly harm an unborn baby, because these drugs are not taken into the body. However, the drugs may keep the mother's body from absorbing vitamins that she and the baby need. Pregnant women who take these drugs should ask their physicians whether they need to take extra vitamins.
BREASTFEEDING. Because cholestyramine and colestipol interfere with the absorption of vitamins, women who use these drugs while breastfeeding should ask their physicians if they need to take extra vitamins.
Women who are breastfeeding should talk to their physicians before using gemfibrozil. Whether this drug passes into breast milk is not known. But because animal studies suggest that it may increase the risk of some types of cancer, women should carefully consider the safety of using it while breastfeeding.
HMG-CoA reductase inhibitors (such as lovastatin, pravastatin, fluvastatin and simvastatin) should not be used by women who are breastfeeding their babies.
OTHER MEDICAL CONDITIONS. Cholesterol-reducing drugs may make some medical problems worse. Before using these drugs, people with any of these medical conditions should make sure their physicians are aware of their conditions:
In addition, people with kidney or liver disease may be more likely to have blood problems or other side effects when they take certain cholesterol-reducing drugs. And some drugs of this type may actually raise cholesterol levels in people with liver disease.
Patients with any of the following medical conditions may develop problems that could lead to kidney failure if they take HMG-CoA reductase inhibitors:
treatments to prevent rejection after an organ transplant
recent major surgery
seizures (convulsions) that are not well controlled
People with phenylketonuria (PKU) should be aware that sugar-free formulations of some cholesterol-reducing drugs contain phenylalanine in aspartame. This ingredient can cause problems in people who have phenylketonuria.
USE OF CERTAIN MEDICINES. Cholesterol-reducing drugs may change the effects of other medicines. Patients should not take any other medicine that has not been prescribed or approved by a physician who knows they are taking cholesterol-reducing drugs.
Gemfibrozil
Studies in animals and humans suggest that gemfibrozil increases the risk of some types of cancer. The drug may also cause gallstones or muscle problems. Patients who need to take this medicine should ask their physicians for the latest information on its benefits and risks.
Patients taking gemfibrozil should check with a physician immediately if any of these side effects occur:
fever or chills
severe stomach pain with nausea and vomiting
pain in the lower back or side
pain or difficulty when urinating
cough or hoarseness
HMG-CoA reductase inhibitors
These drugs may damage the liver or muscles. Patients who take the drugs should have blood tests to check for liver damage as often as their physician recommends. Any unexplained pain, tenderness or weakness in the muscles should be reported to the physician at once.
All cholesterol-reducing drugs
Minor side effects such as heartburn, indigestion, belching, bloating, gas, nausea or vomiting, stomach pain, dizziness and headache usually go away as the body adjusts to the drug and do not require medical treatment unless they continue or they interfere with normal activities.
Patients who have constipation while taking cholesterol-reducing drugs should bring the problem to a physician's attention as soon as possible.
Additional side effects are possible. Anyone who has unusual symptoms while taking cholesterol-reducing drugs should get in touch with his or her physician.
Interactions
Cholesterol-reducing drugs may interact with other medicines. When this happens, the effects of one or both of the drugs may change or the risk of side effects may be greater. Anyone who takes cholesterol-reducing drugs should let the physician know all other medicines he or she is taking and should ask whether the possible interactions can interfere with drug therapy. Examples of possible interactions are listed below.
Some cholesterol-reducing drugs may prevent the following medicines from working properly:
Taking some cholesterol-reducing drugs with blood thinners (anticoagulants) may increase the chance of bleeding.
Combining HMG-CoA reductase inhibitors with gemfibrozil, cyclosporine (Sandimmune) or niacin may cause or worsen problems with the kidneys or muscles.
BOOKS
Nesto, R. W., and L. Christensen. Cholesterol-Lowering Drugs: Everything You and Your Family Need to Know. New York: Morrow, William & Co, 2000.
Parsons, W. B. Cholesterol Control Without Diet! The Niacin Solution. Scottsdale, AZ: Lilac Press, 1998.
Nancy Ross-Flanigan
KEY TERMS
Cell—The basic unit that makes up all living tissue.
Cholesterol—Fatty substance found in tissue. Necessary to maintain a healthy body.
Enzyme—A type of protein, produced in the body, that brings about or speeds up chemical reactions.
Hormone—A substance that is produced in one part of the body, then travels through the bloodstream to another part of the body where it has its effect.
Phenylketonuria—(PKU) A genetic disorder in which the body lacks an important enzyme. If untreated, the disorder can lead to brain damage and mental retardation.
Pituitary gland—A pea-sized gland at the base of the brain that produces many hormones that affect growth and body functions.
