Bile Acid Resins

Summary

Bile Acid Resins (also known as Bile Acid Sequestrants) are lipid-lowering drugs used to reduce cholesterol levels in the bloodstream. The drug names of the bile acid resins include cholestyramine, colesevelam, and colestipol. Mechanistically, bile acid resins work by blocking the reabsorption of bile acids in the intestines. This causes the liver to use cholesterol to make more bile acids, which in turn decreases overall cholesterol levels. On laboratory tests, patients taking these drugs will experience a slight rise in HDL levels, a slight rise in triglyceride levels, and a great fall in LDL levels. Bile acid resins can block the intestinal absorption of both medications and fat-soluble vitamins. A common side effect of taking these drugs is nausea.

Key Points

• Bile Acid Resins
  • Drug Names
    • Cholestyramine
    • Colestipol
    • Colesevelam
  • Clinical Use
    • Lipid lowering drug
      • Used to treat hyperlipidemia (high cholesterol levels)
  • Mechanisms
    • Prevent intestinal reabsorption of bile acids
      • Binds to bile acids and prevents their reabsorption in the distal ileum (impairs enterohepatic circulation)
    • Liver must use cholesterol to make more bile acids
      • Forces the liver to pull cholesterol (LDL) from blood and consume it to make more bile acids
  • Labs
    • ↓↓ LDL
    • Slightly ↑ HDL
    • Slightly ↑ triglycerides
      • Bile acid resins are one of the only lipid lowering drugs that increase triglyceride levels
  • Side Effects
    • GI upset (nausea)
      • Most commonly nausea, bloating, and cramping
    • ↓ absorption of other drugs
      • Bile acid resins can also bind to and impair the absorption drugs like digoxin and warfarin
      • Can be prevented by administering the other drugs one hour before or four hours after the bile acid resins
    • ↓ absorption of fat-soluble vitamins
      • May cause deficiencies in Vitamin A, D, E, and K