Ezetimibe

Etki Mekanizması

Ezetimibe selectively inhibits the NPC1L1 transporter protein located on the luminal surface of enterocytes in the jejunum of the small intestine. NPC1L1 is the critical gateway for intestinal cholesterol absorption, responsible for uptaking both dietary cholesterol and the much larger pool of biliary cholesterol that is recirculated through the enterohepatic cycle. By blocking this transporter, ezetimibe reduces cholesterol delivery to the liver, which in turn upregulates hepatic LDL receptor expression to compensate for the reduced cholesterol supply. This upregulation increases LDL clearance from the bloodstream. The mechanism is entirely complementary to statins, which inhibit HMG-CoA reductase to reduce hepatic cholesterol synthesis. When the liver is deprived of cholesterol from both sources simultaneously, the LDL-lowering effect is significantly amplified. Ezetimibe undergoes glucuronidation in the intestinal wall and liver to form its active metabolite, ezetimibe-glucuronide, which is also pharmacologically active and participates in enterohepatic recirculation, contributing to the drug's prolonged duration of action.