Brand name(s): Questran, LoCHOLEST

Generic name: cholestyramine resin

Preparations: powder (for suspension)

Questran, or cholestyramine, is an oral resin used to bind bile acids. It was originally used to treat itching caused by cholestasis. Its main use is to treat high cholesterol, lowering total cholesterol and LDL, or bad cholesterol, levels. Caution should be used if there is an associated high triglyceride level, because it may increase triglyceride concentrations It is still being used to decrease cholesterol, but usually to prevent or to treat heart disease. Cholestyramine is an old drug first approved by the FDA in 1966. Attempts to make it over the counter have not been successful.

Cholestryamine is also used to treat diarrhea-predominant IBS, cardiac glycoside toxicity, diarrhea associated with excess fecal bile acids (such as in patients with a resected bowel), and pseudomembraneous colitis.

Cholestyramine resin acts by releasing chloride and combining it with bile acids in the intestine to form insoluble, nonabsorbable complexes that are excreted in the feces along with unchanged resin. The excretion in the feces prevents the bile acids from returning to the liver by enterohepatic circulation. Lowering the bile acid concentration in the hepatocytes causes an increased conversion of cholesterol to bile acids, resulting in a replenished supply of these compounds, which are essential components of the bile. This causes a decrease in the intracellular cholesterol concentration, which activates an increased uptake of LDL particles. The final outcome is a decreased plasma cholesterol concentration.

Severe adverse drug-drug interactions may result if cholestyramine is taken with: raloxifene (Evista, an anticancer drug), mycophenolate (immunosuppressant), and hydrocortisone (steroid).

Cholestyramine is well-known to cause drug interactions by binding and decreasing the concentration of many drugs. To minimize drug interactions, other drugs should be taken at least 1 hour before or at least 4—6 hours after taking cholestyramine.

Adverse effects
The most frequent adverse effect that occurs with cholestyramine is constipation. The constipation is usually mild and transient and can produce fecal impaction. It is recommended to drink plenty of water when taking cholestyramine. Other side effects are abdominal pain with cramps, heartburn, nausea, and vomiting. Less frequent effects are headache, dizziness, diarrhea, flatulence, and perianal irritation.

Cholestyramine binds to Vitamin K, which increases the risk for bleeding due to Vitamin K deficiency or affecting warfarin.. Precaution is needed in children and the elderly because of an increased risk of developing acidosis.