Bile Acid Sequestrant
Examples
Cholestyramine
Indications
- Pruritis from a biliary cause
- Diarrhoea associated with Crohn's disease
- Ileal resection or vagotomy
Contraindications
Complete biliary obstruction – not likely to be effective.
Mechanism
Cholestyramine is a resin. It is not absorbed or broken down in the gut. It binds bile salts to form an insoluble molecule that is excreted in faeces. The reduction in circulating bile salts causes a reduction in tissue bile salt deposition which reduces pruritis.
Cholestyramine also acts as a lipid-lowering agent. To compensate for the reduction in bile salts, the body converts cholesterol in the liver into more bile salts.
Administration
Oral (Sachet)
Adverse Reactions
Common
- Constipation
- Nausea
- Vomiting
- Abdominal discomfort
Rare
- Rarely patients can get a prolonged prothrombin time as a result of vitamin K deficiency
- Intestinal Obstruction
Interactions
Cholestyramine can affect the absorption of other drugs so other medications must be taken either 1 hour before or 6 hours after it.
In particular it reduces the absorption of paracetamol, thyroxine, tetracylines, valproate, thiazide diuretics, and mycophenolate.
It increases the elimination of leflunomide and therefore significantly reduces its effects.
It antagonises the effects of oral vancomycin.
It can either enhance or inhibit the effect of warfarin.
Education
Cholestyramine can affect the absorption of other drugs so other medications must be taken either 1 hour before or 6 hours after it.
Reduces the absorption of fat soluble vitamins (Vitamins A, D, E, K and folic acid) therefore patients may need vitamin supplementation.
The sachet content should be mixed with at least 150ml of water or some other suitable liquid such as thin soup, fruit juice or skimmed milk.
Pharmacokinetics
Nil relevant.
