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Bile Acid Sequestrants

Also indexed as: Cholestyramine, Prevalite®, Questran®

Cholestyramine (Questran®) and colestipol (Colestid®) are bile acid sequestrants—a class of drugs that binds bile acids, prevents their reabsorption from the digestive system, and reduces cholesterol levels. Cholestyramine and colestipol are two of many drugs used to lower cholesterol levels in people with high cholesterol.

Bile acids are produced in the liver from cholesterol and secreted into the small intestine to help with the absorption of dietary fat and cholesterol. Bile acid sequestrants bind bile acids in the small intestine and carry them out of the body. This causes the body to use more cholesterol to make more bile acids, which are secreted into the small intestine, bound to bile acid sequestrants, and carried out of the body. The end result is lower cholesterol levels. Bile acid sequestrants also prevent absorption of some dietary cholesterol.

The information in this article pertains to bile acid sequestrants in general. The interactions reported here may not apply to all the Also Indexed As terms. Talk to your doctor or pharmacist if you are taking any of these drugs.

Interactions with Dietary Supplements

Vitamins and Minerals
Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A, D, E, and K.1 2 Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.3 Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.4

Carotenoids
Use of colestipol for six months has been shown to significantly lower blood levels of carotenoids including beta-carotene.5

Interactions with Foods and Other Compounds

Food
Bile acid sequestrants should be taken with plenty of water before meals.6

Summary of Interactions for Bile Acid Sequestrants

Depletion or interference Beta-carotene and other carotenoids
Calcium*
Folic acid
Vitamin A
Vitamin D
Vitamin E
Vitamin K
Zinc*
Adverse interaction None known
Side effect reduction/prevention None known
Supportive interaction None known
Reduced drug absorption/bioavailability None known

For the convenience of the reader, the information in the summary is categorized as follows: “Depletion or interference” indicates the drug may deplete or interfere with the absorption or function of the supplement or herb. “Adverse interaction” indicates that the supplement or herb used together with the drug may result in undesirable effects. “Side effect reduction/prevention” indicates the supplement or herb may reduce the likelihood and/or severity of a potential side effect caused by the drug. “Supportive interaction” indicates the supplement or herb may support or aid the function of the drug. “Reduced drug absorption/bioavailability” indicates that the supplement or herb may decrease the absorption and/or activity of the drug in the body. An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.

References:

1. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 221–2 [review].

2. Threlkeld DS, ed. Diuretics and Cardiovasculars, Antihyperlipidemic Agents, Bile Acid Sequestrants. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Feb 1997, 171i–l.

3. Threlkeld DS, ed. Diuretics and Cardiovasculars, Antihyperlipidemic Agents, Bile Acid Sequestrants. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Feb 1997, 171i–l.

4. Watkins DW, Cassidy MM, Khalafi R, Vahouny GV. Calcium and zinc balances in rats chronically fed the bile salt-sequestrant cholestyramine (Questran). Fed Proc 1983;42:819.

5. Probstfield JL, Lin T, Peters J, Hunninghake DB. Carotenoids and vitamin A: The effect of hypocholesterolemic agents on serum levels. Metabolism 1985;34:88–91.

6. Threlkeld DS, ed. Diuretics and Cardiovasculars, Antihyperlipidemic Agents, Bile Acid Sequestrants. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Feb 1997, 171i–l.