How does cholestyramine work in the body?
Cholestyramine works in the gut by acting as a resin that binds bile acids. These bile acids are normally made in the liver and released into the intestines to help digest fats. When cholestyramine binds bile acids, less bile acid is reabsorbed back into the body. That shifts the body to use more cholesterol to replace the bile acids that were lost, which lowers blood cholesterol levels over time.
How does it affect cholesterol?
Because cholestyramine reduces bile acid reabsorption, the liver has to pull more cholesterol from the bloodstream to make new bile acids. The drop in available cholesterol for bile acid production is linked to lower circulating cholesterol concentrations.
What happens to bile acids after cholestyramine binds them?
Bound bile acids are carried out in the stool rather than being reused. This “interrupts the recycling” (enterohepatic circulation) of bile acids that normally keeps bile acid levels circulating.
Does cholestyramine slow fat digestion or change stool?
By binding bile acids in the intestines, cholestyramine can reduce the efficiency of fat digestion and absorption in the short term. It can also lead to gastrointestinal side effects such as constipation, which is commonly reported with bile-acid binding resins.
Why does cholestyramine interact with other medicines?
Cholestyramine is a bile-acid–binding resin, so it can also bind or interfere with the absorption of certain drugs taken by mouth. Spacing doses from other medications is often needed so the other medicines can be absorbed before cholestyramine binds them in the gut.