Ezetimibe is a cholesterol absorption inhibitor used to lower total cholesterol, LDL-C, Apo-B, and non-HDL-C in primary hyperlipidemia and familial cholesterolemia. Ezetimibe is a lipid-lowering compound that inhibits intestinal cholesterol and phytosterol absorption. Unlike other classes of cholesterol-reducing compounds including statins and bile acid sequestrants, ezetimibe has a distinct mechanism of action involving the sterol transporter Niemann-Pick C1-Like 1 (NPC1L1), and is unique in that it does not affect the absorption of fat-soluble nutrients such as fat-soluble vitamins, triglycerides, or bile acids. Ezetimibe is indicated to reduce elevated total-C, LDL-C, Apo B, and non-HDL-C in patients with primary hyperlipidemia, alone or in combination with an HMG-CoA reductase inhibitor (statin). It is also indicated to reduce elevated total-C, LDL-C, Apo B, and non-HDL-C in patients with mixed hyperlipidemia in combination with fenofibrate, and to reduce elevated total-C and LDL-C in patients with homozygous familial hypercholesterolemia (HoFH), in combination with atorvastatin or simvastatin. Ezetimibe may also be used to reduce elevated sitosterol and campesterol in patients with homozygous sitosterolemia (phytosterolemia). The primary target of ezetimibe is the cholesterol transport protein Niemann-Pick C1-Like 1 (NPC1L1) protein. NPC1L1 is expressed on enterocytes/gut lumen (apical) as well as the hepatobiliary (canalicular) interface and plays a role in facilitating internalization of free cholesterol into the enterocyte in conjunction with the adaptor protein 2 (AP2) complex and clathrin.2 Once cholesterol in the gut lumen or bile is incorporated into the cell membrane of enterocytes, it binds to the sterol-sensing domain of NPC1L1 and forms a NPC1L1/cholesterol complex. The complex is then internalized or endocytosed by joining to AP2 clathrin, forming a vesicle complex that is translocated for storage in the endocytic recycling compartment. Lower cholesterol absorption means that less cholesterol is being delivered to the liver, therefore, the levels of fatty acids in the liver would be low. This would increase plasma LDL uptake to produce fatty acids in the liver. Since apolipoprotein B (apoB) forms part of LDL, lower plasma LDL means apoB levels would also decrease. The most common adverse effects of ezetimibe include headache, runny nose, and sore throat. Less common reactions include body aches, back pain, chest pain, diarrhea, joint pain, fatigue, and weakness.

Ezetimibe Pathway References