Questran - Drug Monograph

Introduction

Questran (cholestyramine) is a bile acid sequestrant medication primarily used to lower cholesterol levels and manage certain gastrointestinal conditions. As a non-systemic resin, it works locally in the gastrointestinal tract without being absorbed into the bloodstream. Questran has been clinically used for decades and remains an important therapeutic option in specific patient populations.

Mechanism of Action

Questran is an anion exchange resin that binds bile acids in the intestinal lumen, forming an insoluble complex that is excreted in feces. This binding prevents the normal enterohepatic recirculation of bile acids, forcing the liver to increase conversion of cholesterol into bile acids. This process depletes hepatic cholesterol stores, leading to increased hepatic LDL receptor activity and subsequent increased clearance of LDL cholesterol from the bloodstream.

Indications

• Primary hyperlipidemia: As adjunctive therapy to diet and other lipid-lowering treatments
• Pruritus associated with partial biliary obstruction
• Digitalis toxicity (off-label use for binding cardiac glycosides)
• Diarrhea associated with bile acid malabsorption
• Binding of certain toxins and medications in overdose situations

Dosage and Administration

• Mix powder with 4-6 ounces of water or other non-carbonated beverage
• Stir vigorously and drink immediately
• May also be mixed with highly fluid soups or pulpy fruits
• Administer other medications at least 1 hour before or 4-6 hours after Questran

• Pediatric use: Safety and effectiveness not established
• Geriatric patients: Use with caution due to potential constipation
• Renal/hepatic impairment: No dosage adjustment required

Pharmacokinetics

Contraindications

• Complete biliary obstruction
• Hypersensitivity to cholestyramine or any component
• Phenylketonuria (contains phenylalanine)

Warnings and Precautions

• May cause constipation, which could lead to fecal impaction
• May reduce absorption of fat-soluble vitamins (A, D, E, K) and folic acid
• Use caution in patients with pre-existing constipation
• May exacerbate hemorrhoids
• Monitor for signs of bleeding due to vitamin K deficiency
• Not recommended during pregnancy unless clearly needed
• Use with caution in pediatric patients

Drug Interactions

• Warfarin: Reduced anticoagulant effect (monitor INR closely)
• Digoxin: Reduced absorption (separate administration by several hours)
• Thiazide diuretics: Reduced absorption
• Thyroid hormones: Reduced absorption
• Propranolol: Reduced absorption
• Fat-soluble vitamins: Reduced absorption
• Many other medications: Potential binding and reduced bioavailability

Adverse Effects

• Constipation (most frequent)
• Abdominal discomfort
• Flatulence
• Nausea
• Heartburn

• Hemorrhoidal exacerbation
• Steatorrhea
• Diarrhea
• Anorexia

• Fecal impaction
• Intestinal obstruction
• Hyperchloremic acidosis
• Vitamin deficiency syndromes
• Bleeding disorders

Monitoring Parameters

• Lipid panel at baseline and every 4-8 weeks until stable, then every 3-6 months
• Serum triglycerides (may increase)
• Bowel function and stool pattern
• Signs of vitamin deficiency (bleeding, night blindness, neuromuscular symptoms)
• Height and weight in children (if used)
• INR in patients on warfarin therapy
• Electrolytes in prolonged high-dose therapy

Patient Education

• Mix powder thoroughly with liquid before drinking
• Maintain adequate fluid intake to prevent constipation
• Report severe constipation, abdominal pain, or rectal bleeding
• Take other medications at least 1 hour before or 4-6 hours after Questran
• Maintain recommended dietary modifications
• Notify dentist or surgeon about Questran use due to potential vitamin K deficiency
• Store at room temperature, away from moisture
• Report any unusual bruising or bleeding

References

1. INSERM. Cholestyramine. In: LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012. 2. Product Information: QUESTRAN® powder. Par Pharmaceutical Companies, Inc. 3. Grundy SM, et al. 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol. J Am Coll Cardiol. 2019;73(24):e285-e350. 4. American College of Gastroenterology. Guidelines on the management of bile acid diarrhea. Am J Gastroenterol. 2010;105(5):1030-1038. 5. Micromedex® Healthcare Series. IBM Watson Health. Cholestyramine. 6. Lexicomp Online®. Hudson, Ohio: Wolters Kluwer Clinical Drug Information, Inc.; 2023.