Lipocol-Merz® (Colestyramine)

Colestyramine is used to modify bile‑acid metabolism and lower lipid levels in several clinical conditions.

• Hypercholesterolemia: reduces LDL‑cholesterol and total cholesterol levels.
• Familial hypercholesterolemia: assists in achieving target lipid concentrations in genetically predisposed patients.
• Pruritus associated with cholestasis: alleviates itching by decreasing circulating bile acids.
• Diarrhea due to bile‑acid malabsorption: binds excess bile acids to reduce watery stools.

• Colestyramine is a non‑absorbable polymer that binds bile acids in the intestinal lumen. By forming an insoluble complex, it prevents enterohepatic recirculation, leading to increased fecal excretion of bile acids. The loss of bile acids stimulates hepatic conversion of cholesterol into new bile acids, thereby lowering circulating LDL‑cholesterol. The binding capacity is dose‑dependent, and the complex is eliminated unchanged in the stool.

Colestyramine may cause gastrointestinal and metabolic reactions, most of which are mild and reversible.

Common Side Effects

• Constipation: reduced bowel motility leading to harder stools.
• Bloating: sensation of abdominal fullness.
• Flatulence: increased intestinal gas.
• Nausea: mild upset stomach.
• Abdominal discomfort: cramping or pain.
• Taste alteration: occasional metallic taste.

Serious or Rare Side Effects

• Severe constipation or bowel obstruction: requires medical evaluation.
• Electrolyte disturbances (e.g., hypokalemia): may occur with prolonged use.
• Fat‑soluble vitamin deficiency (A, D, E, K): can develop with chronic therapy.

Before starting therapy, clinicians should consider several safety measures.

• Assess lipid profile before initiating therapy: baseline LDL‑cholesterol measurement.
• Monitor for worsening constipation: advise adequate fluid and fiber intake.
• Check electrolytes periodically: especially potassium and magnesium.
• Consider vitamin supplementation: fat‑soluble vitamins A, D, E, K may be reduced.
• Avoid concomitant use with other oral medications without spacing: may affect absorption.
• Store at ambient temperature: keep in original container, protect from moisture and heat.

Colestyramine can affect the absorption of several co‑administered drugs.

Major Interactions (Avoid)

• Warfarin: reduced anticoagulant effect, may require dose adjustment.
• Thyroid hormone replacement (levothyroxine): decreased absorption, monitor thyroid function.
• Oral contraceptives: lowered efficacy, consider alternative contraception.

Moderate Interactions (Monitor Closely)

• Digoxin: reduced bioavailability, check serum levels.
• Certain antibiotics (e.g., quinolones, tetracyclines): decreased absorption, separate dosing by at least 2 hours.
• Fat‑soluble vitamin supplements: reduced uptake, monitor vitamin status.