Which statement about bile acid resins like cholestyramine or colestipol is true?

• A. They increase LDL
• B. They bind bile acids, reducing LDL, and should not be used with digoxin or warfarin
• C. They are absorbed and increase cholesterol
• D. They cause significant weight loss

Answer: (B)

Bile acid resins work in the gut by binding bile acids, forming insoluble complexes that are excreted in stool. This interrupts the enterohepatic circulation of bile acids, so the liver must use more cholesterol to synthesize new bile acids. The result is lower hepatic cholesterol and upregulation of LDL receptors, which pulls more LDL out of the bloodstream, reducing plasma LDL levels.

Because these resins are not absorbed, they lower cholesterol but can interfere with the absorption of other drugs taken orally. They can bind digoxin and warfarin in the gut, reducing their absorption and effectiveness, which is why they’re generally used with caution or spaced apart from these medications.

Other statements don’t fit: they don’t increase LDL or cholesterol; they don’t cause weight loss; and they’re not absorbed themselves.