Cholestyramine is used as an adjunct to diet and lifestyle modification to reduce elevated serum cholesterol levels in patients with primary hypercholesterolemia (particularly elevated LDL). Lowering serum cholesterol may help decrease the risk of atherosclerotic coronary artery disease and myocardial infarction. It is also beneficial in patients with combined hypercholesterolemia and hypertriglyceridemia, although it is not recommended when hypertriglyceridemia is the predominant abnormality. Additionally, cholestyramine is used for symptomatic treatment of bile acid–induced diarrhea associated with short bowel syndrome and for relieving itching (pruritus) related to partial biliary obstruction.

To familiarize the patient with Cholestyramine Resin Light Powder and to minimize gastrointestinal side effects, it is desirable to begin all therapy with one dose daily. Dosage is then increased within a day or two to the desired level for effective control. Motivation of the patient to continue the prescribed regimen in spite of gastrointestinal problems is important. Physician encouragement and supervision are essential for successful management. The recommended adult dose is 4 grams of cholestyramine resin, one to six times daily. Dosages may be adjusted as required to meet the patient's needs. A pediatric dosage schedule has not been established.

As an anion-exchange resin, cholestyramine can bind to various negatively charged substances beyond bile acids. Therefore, co-administered drugs may have altered absorption, and the extent of interaction can vary depending on the drug’s properties and dosage. It is generally assumed that cholestyramine may interfere with the absorption of many concurrently administered medications unless proven otherwise.

Cholestyramine may delay or reduce the absorption of several oral drugs, including thyroid hormones, warfarin, thiazide diuretics, phenylbutazone, phenobarbital, tetracycline, penicillin G, and digitalis. Discontinuation of cholestyramine may increase the risk of toxicity from drugs such as digitalis if doses were previously adjusted. Dose readjustment of such medications may be required upon stopping cholestyramine. It may also interfere with the pharmacokinetics of drugs undergoing enterohepatic circulation, such as estrogens.

Studies have shown that cholestyramine may reduce the bioavailability of HMG-CoA reductase inhibitors (statins); however, their combined use may produce additive cholesterol-lowering effects.

Cholestyramine is contraindicated in patients with complete biliary obstruction where bile cannot enter the intestine, and in individuals with known hypersensitivity to any component of the preparation.

The most common side effect is constipation, particularly at higher doses and in older patients. In most cases, it is mild and temporary and can be managed with standard treatment, though some patients may require dose reduction or discontinuation.

Less common adverse effects include abdominal discomfort, bloating, nausea, vomiting, diarrhea, heartburn, loss of appetite, indigestion, and fatty stools (steatorrhea). Prolonged use may lead to deficiencies of fat-soluble vitamins (A, D, and K), which can result in conditions such as night blindness, bleeding tendencies, or bone disorders. Other rare effects include hyperchloremic acidosis (especially in children), osteoporosis, skin rash, and irritation of the skin, tongue, or perianal area.

Pregnancy: Since cholestyramine is not systemically absorbed, it is unlikely to cause direct fetal harm when used at recommended doses. However, there are no well-controlled studies in pregnant women, and its interference with the absorption of fat-soluble vitamins may pose risks even with supplementation.

Nursing Mothers: Caution is advised when administered during lactation. Reduced absorption of essential vitamins may affect the nursing infant. The benefits of therapy should be carefully weighed against potential risks to both mother and child.

Use in Children: The long-term safety and effectiveness of cholestyramine in children have not been fully established, and appropriate dosing guidelines are not well defined.

Geriatrics: Clinical data in elderly patients are limited; however, individuals over 60 years of age may be more susceptible to gastrointestinal adverse effects.

Store at room temperature between 15°C and 30°C. Protect from moisture.