Ezetimibe Inhibition Research Articles

Impact of micelle characteristics on cholesterol absorption and ezetimibe inhibition: Insights from Niemann-Pick C1-like 1 binding and molecular structure

Yamanashi et al., conducted a study on the absorption of cholesterol and β-sitosterol, as well as the inhibitory effect of ezetimibe (EZE). They used CaCo-2 cells to simulate the intestines and investigated how different mixed micelles, acting as carriers, were absorbed into these cells through the Niemann-Pick C1-like 1 (NPC1L1) protein. The study focused on the impact of micelle shape, size, and zeta potential on absorption and the inhibitory effect of EZE. I utilized small-angle X-ray scattering and a zeta potential measuring device to measure these characteristics. The findings revealed a two-step mechanism: NPC1L1 selectively bound micelles based on their shape and size, and once bound, the absorption was regulated by the molecular structure of the micelle components. EZE's inhibitory effect changed with micelle composition, influencing micelle size and shape. EZE initially acted on the micelle’s shape and size, and then NPC1L1 selectively bound micelles based on their shape and size, allowing EZE to directly inhibit absorption by interacting with NPC1L1. This groundbreaking discovery challenges existing concepts and holds significant implications for researchers in drug development, as well as physicians and pharmacists.

Cryo-EM structures of NPC1L1 reveal mechanisms of cholesterol transport and ezetimibe inhibition.

The intestinal absorption of cholesterol is mediated by a multipass membrane protein, Niemann-Pick C1-Like 1 (NPC1L1), the molecular target of a cholesterol lowering therapy ezetimibe. While ezetimibe gained Food and Drug Administration approval in 2002, its mechanism of action has remained unclear. Here, we present two cryo-electron microscopy structures of NPC1L1, one in its apo form and the other complexed with ezetimibe. The apo form represents an open state in which the N-terminal domain (NTD) interacts loosely with the rest of NPC1L1, leaving the NTD central cavity accessible for cholesterol loading. The ezetimibe-bound form signifies a closed state in which the NTD rotates ~60°, creating a continuous tunnel enabling cholesterol movement into the plasma membrane. Ezetimibe blocks cholesterol transport by occluding the tunnel instead of competing with cholesterol binding. These findings provide insight into the molecular mechanisms of NPC1L1-mediated cholesterol transport and ezetimibe inhibition, paving the way for more effective therapeutic development.

Simvastatin‐Ezetimibe‐Induced Hepatic Failure Necessitating Liver Transplantation

Abstract Serum aminotransferase elevations are a commonly known adverse effect of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin) therapy. However, hepatotoxic events have not been widely published with ezetimibe or the combination agent simvastatin-ezetimibe. We describe a 70-year-old Hispanic woman who developed fulminant hepatic failure necessitating liver transplantation 10 weeks after conversion from simvastatin 40 mg/day to simvastatin 10 mg-ezetimibe 40 mg/day. The patient's lipid panel had been maintained with simvastatin for 18 months before the conversion without evidence of hepatotoxicity. A routine laboratory work-up 10 weeks after conversion revealed elevated serum aminotransferase levels. Simvastatinezetimibe and escitalopram (which she was taking for depression) were discontinued, and other potential causes of hepatotoxicity were excluded. A repeat work-up revealed further elevations in aminotransferase levels, and liver biopsy revealed evidence of moderate-to-severe drug toxicity. She underwent liver transplantation with an uneventful postoperative course. Her aminotransferase levels returned to normal by postoperative day 23, and her 2-year follow-up showed no adverse events. Ezetimibe undergoes extensive glucuronidation by uridine diphosphate glucoronosyltransferases (UGT) in the intestine and liver and may have inhibited the glucuronidation of simvastatin hydroxy acid, resulting in increased simvastatin exposure and subsequent hepatotoxicity. To our knowledge, this is the first case report of simvastatin-ezetimibe-induced liver failure that resulted in liver transplantation. We postulate that the mechanism of the simvastatinezetimibe-induced hepatotoxicity is the increased simvastatin exposure by ezetimibe inhibition of UGT enzymes. Clinicians should be aware of potential hepatotoxicity with simvastatin-ezetimibe especially in elderly patients and should carefully monitor serum aminotransferase levels when starting therapy and titrating the dosage.