Pharmacology · Class
Bile acid sequestrants !
Non-absorbed resins that trap bile acids in the gut. The liver uses cholesterol to make new bile acids, so LDL falls.
Updated 2026-11-01
What they are
Positively charged polymers (colestyramine, colestipol, colesevelam) taken by mouth that are not absorbed. They lower LDL and can raise triglycerides.
Mechanism of action
The resins bind negatively charged bile acids in the intestine and carry them out in the stool, breaking the enterohepatic circulation that normally recovers almost all bile acids. The liver converts more cholesterol into bile acids (CYP7A1, cholesterol 7α-hydroxylase), hepatic cholesterol falls and LDL receptors rise, so LDL is cleared from the blood. The liver also makes more cholesterol and VLDL, which limits the effect and can raise triglycerides.
Target: Bile acids in the intestinal lumen (non-absorbed anion-exchange resins)
Drugs in this class
- ColestyramineA resin powder that binds bile acids in the gut. It lowers LDL cholesterol and relieves itching caused by partial bile…Bile acids in the gut lumen
- ColesevelamA bile acid sequestrant that lowers LDL and also modestly lowers glucose in type 2 diabetes. Fewer drug-binding…Bile acids in the gut lumen
Others in the class
- colestipol
Test yourself
Think of the answer, then tap the question to see it.
How does binding bile acids in the gut lower LDL in the blood?
The liver uses more cholesterol to make new bile acids, hepatic cholesterol falls and LDL receptors rise, clearing LDL.
Why are sequestrants avoided in very high triglycerides?
The liver compensates by making more VLDL, so triglycerides can rise and pancreatitis risk increases.
How are other oral drugs timed around colestyramine?
At least 1 hour before or 4 to 6 hours after it, because the resin binds them in the gut.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - CHOLESTYRAMINE powder, for suspension (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 37 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.