Cholestyramine powder (Questran®, Questran® Lite, Prevalite®), colestipol powder and tablets (Colestid®) and colesevelam tablets (Welchol®)
Efficacy
• In the Lipid Research Clinics Coronary Primary Prevention Trial (LRD-CPPT), a 19% reduction in risk of fatal and non-fatal MI was seen
in patients taking cholestyramine 24 g/day. In those patients who didn't take 24 g/day, a linear relationship was seen with reduction in CH
risk corresponding to cholestyramine dose and reduction in LDL-cholesterol (Lipid Research Clinics Program, 1984 [A]).
• LDL-cholesterol lowered 15%-30% (dose dependent).
• Triglycerides may increase 15% – should not be used as sole therapy if triglycerides are greater than 200 mg/dL and should not be used
at all if triglycerides are greater than 400 mg/dL.
• Effects apparent within one week and maximum at two to three weeks.
• Useful for patients with moderately elevated LDL-cholesterol.
• Good for combination therapy.
• LDL-cholesterol reductions enhanced with low doses.
• Most potent with statin.
• Not systemically absorbed – side effects limited to GI tract.
• Patients who have phenylketonuria (PKU) should know that Questran® Lite, Prevalite®, and flavored colestipol powder contain
aspartame. Regular Questran® and unflavored colestipol powder and tablets do not.
• Drug interactions are minimized by taking other medications one hour before the sequestrant or four hours after.
• The net effect of combination warfarin is unpredictable. Cholestyramine decreases the absorption of warfarin and may reduce warfarin's
half-life by interfering with enterohepatic circulation. Vitamin K absorption may also be reduced; thus, the net effect on coagulation is hard
to predict. Colestipol and colesevelam have been reported not to interact with warfarin, and thus may be safer agents. Separating these
agents by at least four hours from warfarin and close monitoring of INR is recommended.
• While not contraindicated in pregnancy and lactation, consideration must be given to potential adverse effects on the baby because of
impaired maternal absorption of nutrients and vitamins. Dosing
• With cholestyramine and colestipol, dosing is limited by patient tolerance of constipation. Constipation may occur less often with
colesevelam.
• Cholestyramine or colestipol – initiate with very low dose (1/2 scoop or one to two tablets with largest meal) and titrate slowly (increasing
every one to two weeks to 1 scoop or four to five tablets twice a day with meals). Dose can be increased further if tolerated. The maximum
daily dose for cholestyramine is 24 grams/day. The maximum dose for colestipol is 30 grams/day powder, 16 tablets/day.
• Colesevelam – 3 tablets twice a day with meals or 6 tablets daily with a meal. Maximum daily dose is 7 tablets/day.
• Powders must be mixed in liquid or food with high moisture content (e.g., gelatin, applesauce, soup [add only after heating], non-fat
yogurt) prior to ingestion. Palatability of the powders may be improved by mixing a day ahead and storing in the refrigerator. Tablets must
be taken with a liquid.
• Activity: cholestyramine 4 grams = cholestipol 5 grams = colesevelam 1.9 grams.
Please consult manufacturer's product labeling insert, or PDR for full prescribing information.
(Lipid Research Clinics Program, 1984 [A]; McKenney, 2001b [R]; National Cholesterol Education Program, 2001 [R])
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