Usage
- Medical Conditions: Cholestyramine is prescribed as adjunctive therapy to diet and exercise for the reduction of elevated serum cholesterol in patients with primary hypercholesterolemia (elevated low-density lipoproteins). It’s also used for lowering elevated cholesterol in patients with combined hypercholesterolemia and hypertriglyceridemia (when hypertriglyceridemia is not the primary concern), for symptomatic control of bile acid-induced diarrhea due to short bowel syndrome, and for the relief of pruritus associated with partial biliary obstruction.
- Pharmacological Classification: Bile acid sequestrant.
- Mechanism of Action: Cholestyramine binds to bile acids in the intestine, forming insoluble complexes that are excreted in the feces. This interrupts the enterohepatic circulation of bile acids. As the liver uses cholesterol to synthesize new bile acids to replace those lost, serum cholesterol levels decrease.
Alternate Names
- International/Regional Variations: There are no significant international variations in the generic name.
- Brand Names: Questran, Questran Light, Prevalite, Locholest, JAMP-Cholestyramine (Note: Brand availability may vary by region. Questran is discontinued in the US.)
How It Works
- Pharmacodynamics: Cholestyramine lowers LDL cholesterol by binding to bile acids, promoting their excretion. It can also reduce the absorption of fat-soluble vitamins and some medications.
- Pharmacokinetics: Cholestyramine is not absorbed systemically and remains within the gastrointestinal tract. It’s excreted in the feces.
- Mode of Action: Cholestyramine acts by binding bile acids in the intestinal lumen. The resin releases chloride ions and binds to bile acids, forming an insoluble complex that is not absorbed and is excreted in the feces.
- Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: Cholestyramine doesn’t bind to receptors, inhibit enzymes, or modulate neurotransmitters in the traditional sense. Its action is primarily based on its physical binding properties within the digestive tract.
- Elimination Pathways: Primarily fecal excretion.
Dosage
Standard Dosage
Adults:
- Initial dose: 4 g (1 packet or 1 level scoopful) orally once or twice daily.
- Maintenance dose: 8–16 g daily, divided into two doses.
- Maximum dose: 24 g daily (divided into 1 to 6 doses).
Children:
- 240 mg/kg/day of anhydrous cholestyramine resin divided into 2–3 doses.
- Maximum dose generally not to exceed 8 g/day.
- Pediatric safety and efficacy for long-term use are not fully established.
Special Cases:
- Elderly Patients: Similar to adult dosing, but start with a lower dose and titrate cautiously. Monitor closely for gastrointestinal side effects.
- Patients with Renal Impairment: No dose adjustment necessary.
- Patients with Hepatic Dysfunction: Use with caution. Dosage modifications may be needed, especially in patients with biliary obstruction.
- Patients with Comorbid Conditions: Use with caution in patients with constipation or hemorrhoids. For patients with phenylketonuria, the sugar-free form of cholestyramine may be preferred as it contains less phenylalanine than some other formulations.
Clinical Use Cases
Cholestyramine is not typically indicated for the clinical scenarios listed below: Intubation, Surgical Procedures, Mechanical Ventilation, Intensive Care Unit (ICU) Use, Emergency Situations. Its primary use is in managing chronic conditions like hyperlipidemia and bile acid-induced diarrhea.
Dosage Adjustments
- Pre-existing constipation: Start with 4 g orally once a day for 5–7 days, and increase to twice daily, monitoring for constipation and serum lipoproteins at least twice, 4–6 weeks apart.
Side Effects
Common Side Effects
- Constipation
- Bloating
- Stomach pain
- Gas
- Upset stomach
- Nausea
- Vomiting
- Diarrhea
- Loss of appetite
- Irritation of the tongue and perianal area
Rare but Serious Side Effects
- Severe constipation or fecal impaction
- Bowel obstruction
- Bleeding due to vitamin K deficiency
- Allergic reactions (hives, difficulty breathing, swelling)
Long-Term Effects
- Vitamin deficiencies (A, D, E, and K)
- Osteoporosis
- Tooth discoloration or enamel erosion with prolonged contact
Adverse Drug Reactions (ADR)
- Severe allergic reactions
- Worsening of pre-existing constipation
- Hyperchloremic metabolic acidosis (rarely)
Contraindications
- Hypersensitivity to cholestyramine or bile acid sequestrants
- Complete biliary obstruction
Drug Interactions
Cholestyramine can bind to and decrease the absorption of various medications, including:
- Warfarin
- Thiazide diuretics
- Digoxin
- Thyroid hormones
- Oral contraceptives
- Antiepileptic drugs
- Some antibiotics
It is important to administer other oral medications at least 1 hour before or 4 to 6 hours after cholestyramine.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: C. While cholestyramine is not absorbed systemically, it may interfere with the absorption of fat-soluble vitamins essential for fetal development. Use only if the potential benefit justifies the potential risk to the fetus.
- Breastfeeding: Cholestyramine does not pass into breast milk, but it may reduce the absorption of vitamins in the mother, potentially impacting the vitamin content of breast milk.
Drug Profile Summary
- Mechanism of Action: Binds bile acids, promoting their excretion, and subsequently lowers cholesterol levels.
- Side Effects: Constipation, bloating, stomach pain, nausea.
- Contraindications: Complete biliary obstruction, hypersensitivity.
- Drug Interactions: Numerous; separate administration of other oral medications by at least 1 hour before or 4–6 hours after.
- Pregnancy & Breastfeeding: Use with caution. Monitor vitamin levels.
- Dosage: Adults: 4–24 g daily. Children: 240 mg/kg/day.
- Monitoring Parameters: Serum cholesterol and triglyceride levels, signs of constipation, vitamin levels.
Popular Combinations
Cholestyramine is not usually used in combination with other lipid-lowering therapies due to potential drug interactions and diminished efficacy of concomitant drugs.
Precautions
- General Precautions: Monitor for gastrointestinal side effects, especially constipation. Supplement fat-soluble vitamins if necessary. Monitor cholesterol and triglyceride levels. Ensure adequate hydration. Maintain good oral hygiene.
- Specific Populations: Use caution in pregnancy, breastfeeding, and pediatric patients.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Cholestyramine?
A: Adults: Start with 4 g once or twice daily, increasing to 8–16 g/day divided into two doses, not to exceed 24 g/day. Children: 240 mg/kg/day divided into 2–3 doses, not exceeding 8 g/day.
Q2: How should Cholestyramine be administered?
A: Mix the powder with water, juice, or other non-carbonated fluids before ingesting. Do not take in dry form. It can also be mixed with watery soups or pulpy fruits.
Q3: What are the most common side effects of Cholestyramine?
A: The most common side effects are gastrointestinal, including constipation, bloating, nausea, and stomach discomfort.
Q4: Are there any serious side effects of Cholestyramine?
A: While rare, serious side effects include severe constipation, bowel obstruction, bleeding (due to potential Vitamin K deficiency), and allergic reactions.
Q5: What should patients do if they experience constipation while taking Cholestyramine?
A: Increasing fluid intake, including fiber in the diet, and using stool softeners may help relieve constipation. If it persists or worsens, consult the prescribing physician for potential dose adjustments.
Q6: Can Cholestyramine be taken during pregnancy or while breastfeeding?
A: It should be used cautiously during pregnancy and breastfeeding. It may reduce the absorption of vitamins. Consult with a physician to weigh the risks and benefits.
Q7: Does Cholestyramine interact with other medications?
A: Yes, Cholestyramine can significantly interact with various medications. Other medications should be taken at least 1 hour before or 4-6 hours after cholestyramine to minimize the risk of impaired absorption.
Q8: What are the long-term effects of taking Cholestyramine?
A: Potential long-term effects include vitamin deficiencies (A, D, E, and K), which may necessitate supplementation. Tooth discoloration and enamel erosion can occur if the medication is in prolonged contact with teeth. Good oral hygiene is recommended.
Q9: What is the mechanism of action of Cholestyramine in relieving pruritus associated with partial biliary obstruction?
A: In partial biliary obstruction, excess bile acids can deposit in the skin, causing itching. Cholestyramine binds these bile acids in the intestine, reducing their circulating levels and thus alleviating the pruritus.
