In this VETgirl online veterinary continuing education blog, we review the use of cholestyramine in the veterinary poisoned patient. If you contact the ASPCA Animal Poison Control Center (888) 426-4435), their veterinary toxicology staff may recommend cholestyramine as part of decontamination. But what exactly is it? Is it the same thing as activated charcoal and do I really need to get it?

Cholestyramine (Questran) is a bile acid sequestrant and anti-lipemic agent.1 Cholestyramine works by combining with the bile acids in the intestines and forming an insoluble complex that is then excreted in the feces.1 This results in “partial removal of the bile acids from the enterohepatic circulation by preventing their absorption.”1

What toxicants should I use it for in the veterinary poisoned patient?

Cholestyramine is thought to help bind bile in the gut as an effective decontaminant method for certain toxicants such as:

• Blue green algae (microcystins)
• Vitamin D (cholecalciferol)
• Anticoagulant rodenticides (although we’ll rarely see these anymore, as they have been transitioned out by cholecalciferol and bromethalin in the United State)
• Beta blockers
• Dgitalis/digitoxin
• Certain NSAIDs (e.g., piroxicam, diclofenac, naproxen, ibuprofen)
• Phenobarbital
• Tetracyclines
• Methotrexate
• Phenytoin
• Sago palm (Cycad palm).2-4,a

The use of cholestyramine has recently been utilized more in veterinary decontamination. According to the ASPCA Animal Poison Control Center (APCC), it is thought to “decrease the body burden of vitamin D3” as cholecalciferol undergoes enterohepatic recirculation with bile acids.2 Note that the efficacy has not been well documented in clinical practice, however.

Where do I get it?
You can purchase cholestyramine from human pharmacies or even veterinary supply companies. It isn’t very expensive, and if you’re an emergency clinic or specialty clinic, you should have this in stock (IMO, specifically for Vitamin D3 toxicosis).

What’s the dose in veterinary medicine?
Current recommended doses of cholestyramine from the ASPCA APCC are: 0.3–0.5 g/kg, dissolved in liquid and administered orally every 6–8 hr for 3–5 days, depending on the initial dose of cholecalciferol ingested.2 Other resources have a higher dose at: 0.3-1 g/kg TID X 4 days or 1-2 g/dog BID, 1 g/cat BID.5 Contraindications for the use of cholestyramine include patients with complete biliary obstruction and hypersensitivity to cholestyramine. With chronic administration, Vitamin K1 should be supplemented to prevent secondary depletion.

When in doubt, contact the ASPCA Animal Poison Control Center (888) 426-4435) for more life saving information!

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