Cholestyramine

Cholestyramine

Clinical data
Trade names	Questran
AHFS/Drugs.com	monograph
MedlinePlus	a682672
Pregnancy cat.	C (US)
Legal status	?
Routes	gastrointestinal
Pharmacokinetic data
Metabolism	bile acids
Half-life	.1 hr
Excretion	feces
Identifiers
CAS number	11041-12-6 Y
ATC code	C10AC01
DrugBank	DB01432
UNII	4B33BGI082 N
KEGG	D02690 Y
ChEMBL	CHEMBL1201625 N
Chemical data
Formula	?
Mol. mass	Average MW exceeds 106 Daltons
N (what is this?)  (verify)

Cholestyramine or colestyramine (Questran, Questran Light, Cholybar) is a bile acid sequestrant, which binds bile in the gastrointestinal tract to prevent its reabsorption. It is a strong ion exchange resin, which means that it can exchange its chloride anions with anionic bile acids in the gastrointestinal tract and bind them strongly in the resin matrix. The functional group of the anion exchange resin is a quaternary ammonium group attached to an inert styrene-divinylbenzene copolymer.

Cholestyramine removes bile acids from the body by forming insoluble complexes with bile acids in the intestine, which are then excreted in the feces. When bile acids are excreted, plasma cholesterol is converted to bile acid to normalize bile acid levels. This conversion of cholesterol into bile acids lowers plasma cholesterol concentrations.

Medical uses

Bile acid sequestrants such as cholestyramine are primarily used to treat hypercholesterolemia, but can also be used to treat the pruritus, or itching, that often occurs during liver failure, due to the liver's inability to eliminate bile.

Cholestyramine is also used to prevent diarrhea in Crohn's disease patients who have undergone ileal resection. The terminal portion of the small bowel (ileum) is where bile acids are reabsorbed. When this section is removed, the bile acids pass into the large bowel and attract water due to their osmotic effect, causing diarrhea. Cholestyramine prevents this increase in water by making the bile acids insoluble and osmotically inactive. Post-ileal resection patients should use this medication cautiously, however, because bowel surgery heightens the occurrence of small-bowel obstructions, and there are several reports in the medical literature of Cholestyramine causing bowel obstructions. Cholestyramine can also be used in the treatment of Clostridium difficile infections, in order to adsorb toxins A and B, and reduce the diarrhea and other symptoms that these toxins cause, however, because it is not an anti-infective it is used in concert with vancomycin. Cholestyramine can also be used in the control of the diarrhea form of Irritable Bowel Syndrome (IBS-D). It is also used in the "wash out" procedure in patients taking leflunomide to aid drug elimination in the case of severe side effects caused by leflunomide.

Available forms

Cholestyramine is available as powder form, in 4 gram packets, or in larger canisters. In the United States, it can be purchased either as a generic medicine, or as Questran or Questran Light (Bristol-Myers Squibb).

Dosage

4 to 8 grams once or twice daily, maximum dose 24 grams a day.

Side-effects

The following side effects have been noted.

• Most frequent: Constipation
• Seldom: tooth discoloration, tooth enamel erosion, and premature tooth decay, all from prolonged oral exposure to the suspension
• Increased risk for gallstones due to increased cholesterol concentration of bile.
• Increased plasma triglycerides

Warnings

Patients with hypothyroidism, diabetes, nephrotic syndrome, dysproteinemia, obstructive liver disease, kidney disease, or alcoholism should consult their doctor before taking this medication. Other drugs should be taken at least one hour before or four to six hours after cholestyramine to reduce possible interference with absorption.

Patients with phenylketonuria should consult with a physician before taking Questran Light because that product contains phenylalanine.

Drug interactions

The following interactions have been noted.

• Digitalis
• Estrogens and progestins
• Oral diabetes drugs
• Penicillin G
• Phenobarbital
• Spironolactone
• Tetracycline
• Thiazide-type diuretic pills
• Thyroid medication
• Warfarin
• Leflunomide

Most interactions are due to the risk of decreased absorption of these drugs.

Duration of treatment

The duration of treatment is not limited, but the prescribing physician should reassess at regular intervals if continued treatment is still necessary.

Overdose

Principal overdose risk is blockage of intestine or stomach.

Other remarks

Cholestyramine may interfere in the absorption of fat soluble vitamins such as vitamins A, D, E, and K. There are no special considerations regarding alcohol consumption.

Cholestyramine is also used in treatment of individuals experience chronic inflammation of the innate immune system following exposure to damp and water-damaged indoor environments. This method of treatment was first introduced by Ritchie Shoemaker, MD to treat people experiencing chronic inflammation after exposure to a certain species of algae in estruaries. Although it is suspected that the cholestyramine is binding to biological toxins produced by the molds and bacteria, the exact compounds being removed that were responsible for the inflammation have not been identified. Currently, it is generally believed that the cholestyramine is binding to and removing any number of inflammagens found on and within the bacteria and mold present in damp and water-damaged environments.

A 5% compound with Aquaphor can be applied as a topical diaper rash ointment for infants and toddlers.

(Shoemaker, Ritchie C. Mold Warriors)

References

• The Merck Index (12 ed.). p. 2257. 

External links

• U.S. National Library of Medicine: Drug Information Portal - Cholestyramine