Cholestyramine

Cholestyramine is an anion-exchange resin and belongs to the class of bile acid sequestrants. Cholestyramine contains positively charged amino groups that can bind negatively charged bile salts in the intestine to form insoluble complexes. These bile acid complexes cannot be reabsorbed and are excreted in the feces. To compensate for bile acid loss, the liver increases the conversion of cholesterol into bile acids by upregulating the expression of cholesterol 7α-hydroxylase. As hepatic cholesterol levels fall, hepatocytes upregulate low-density lipoprotein (LDL) receptor expression, which increases the uptake of plasma LDL and lowers the concentration of LDL-cholesterol in the blood.