cholestyramine (Questran)

Introduction

Tradename: Questran.

Indications

• hypercholesterolemia* (increased LDL)
• pruritus associated with elevated levels of bile acids
• diarrhea associated with excess fecal bile acids
• binding of toxic agents
• pseudomembranous colitis
• adjunctive treatment of digitalis toxicity
• treatment of enteric hyperoxaluria

* Especially useful when inflammatory liver disorder coexists with hyperlipidemia, making use of niacin & HMG CoA reductase inhibitors (statins) problematic.

Dosage

• start 4 g PO QD/BID
• maintenance: 4 g PO 1-5 times/day

Tabs: 1g

Powder: 4 g/9 g of powder (378 g) 4 g/5 g of powder (378 g) with aspartame (Questran Light)

Pharmacokinetics

• not abdorbed from the GI tract
• peak effects within 21 days

elimination via feces

Adverse effects

• constipation (1-10%)
• abdominal pain
• abdominal distention
• flatulence
• nausea/vomiting
• diarrhea
• increased levels of triglycerides
• rash
• irritation of perianal area, skin or tongue
• hyperchloremic acidosis
• malabsorption of fat-soluble vitamins
• increased urinary Ca+2 excretion*
• may increase homocysteine levels
• may increase serum transaminase levels

* but decreases hyperoxaluria

• drug adverse effects of anti-hyperlipidemic agents

Drug interactions

• interferes with absorption of many medications

• drug interaction(s) of beta-adrenergic receptor antagonists with cholestyramine

Mechanism of action

• depletes bile acid pool
• removes plasma LDL
• upregulates hepatic LDL receptors
• binds oxalate when excessive free fatty acids bind calcium

More general terms

• bile acid sequestrant