Bile-acid resins and similar agents include:
- The powders cholestyramine (Questran and Questran Light)
- The tablet colesevelam hydrochloride (Welchol), which is proving to lower
LDL without as many side effects (e.g., constipation)
Bile-acid binding resins work, as their name suggests, by binding to bile
in the digestive tract. This reduces cholesterol in the following way:
- As part of normal digestion, the liver turns cholesterol into bile acids.
These bile acids move into the intestines, where most of them are re-absorbed
and returned to the liver.
- Bile-acid resin drugs bind to bile acids as they move through the intestines
-- so that the bile acids exit your body with the feces, rather than re-enter
the blood stream.
- In response, the liver converts more cholesterol into bile acids -- and
these, too, are cleared from the body through the feces.
- The result is that LDL ("bad") cholesterol is effectively removed from
your liver and your blood.
When used with dietary control, bile acid resins can reduce LDL levels by
15 - 20%. When bile acid resins are combined with nicotinic acid, LDL levels
can drop as much as 40 - 60%.
Often, people experience constipation, heartburn, gas, and other gastrointestinal
problems while taking a drug in this class. These symptoms can become so bothersome
that the person wants to change medications.
Colesevelam, the newer resin, appears to produce fewer of the gastrointestinal
side effects described.
Over time, deficiencies of vitamins A, D, E, K, and B9 (folic acid) may occur,
and vitamin supplements may be necessary. If long-term use of bile acid resins
leads to depletion of vitamin K in the body, bleeding problems may occur.
Rarely, toxic effects on the liver have been reported. Patients with liver
disorders should be monitored.
Bile-acid binding resins may interfere with other medications, including:
- Digoxin (Lanoxin)
- Beta-blocker drugs for high blood pressure (such as atenolol, metoprolol,
- Sulfonylureas (such as glimepiride and glyburide) used to treat diabetes
In order to prevent drug interactions, take medications 1 hour before or 4
- 6 hours after taking the bile acid-binding resins.
Review Date: 10/31/2006
Reviewed By: Alan Greene, M.D., F.A.A.P., Department of Pediatrics, Packard Children's Hospital, Stanford University School of Medicine; Chief Medical Officer, A.D.A.M., Inc.
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