Management of Bile Acid Diarrhea in Patients on Cholestyramine

Diagnosis and Assessment

The Canadian Association of Gastroenterology recommends diagnostic testing with SeHCAT or serum 7α-hydroxy-4-cholesten-3-one (C4) over empiric therapy for patients with suspected bile acid diarrhea 4, 6
Key risk factors to assess for bile acid diarrhea include history of cholecystectomy, terminal ileal resection or disease, abdominal radiotherapy, or features of irritable bowel syndrome with diarrhea 4, 5

If cholestyramine is causing the diarrhea, discontinue it immediately and switch to an alternative lipid-lowering agent, as the diarrhea should resolve within days to weeks of stopping the offending agent 3
For patients with concurrent bile acid diarrhea despite being on cholestyramine, increase the cholestyramine dose gradually to 12-16g daily, which is the therapeutic range for bile acid diarrhea 1, 2, 5
The American Gastroenterological Association suggests that patients with bile acid diarrhea may require long-term maintenance therapy, with 39-94% of patients experiencing recurrent diarrhea when cholestyramine is withdrawn 2, 3, 5

Colesevelam is a better-tolerated alternative to cholestyramine and does not have the same palatability issues, with a recommended dose of two tablets twice daily 2, 3
Loperamide is the first-line alternative antidiarrheal agent for patients who cannot tolerate bile acid sequestrants, particularly effective in less severe bile acid malabsorption 2

Monitor fat-soluble vitamins (A, D, E, K) in patients on long-term cholestyramine therapy, as vitamin D deficiency occurs in 20% of patients 2, 3, 5
Monitor serum bicarbonate and chloride levels to detect hyperchloremic metabolic acidosis, especially critical in patients with renal impairment or volume depletion 2, 3, 5
All other medications must be taken at least 1 hour before or 4-6 hours after cholestyramine to avoid impaired absorption 2, 3