Remimazolam Hydrolysis Mediated by Carboxylesterase1 and Impact of Genetic Variations and Inhibitors

Abstract ID 128195 Poster Board 438 Remimazolam (Byfavo®), a recent FDA-approved ester-linked benzodiazepine for sedation, offers advantages in sedation with its rapid action and predictable duration, making it suitable for broad anesthesia use. Its favorable pharmacological profile is primarily attributed to rapid hydrolysis, the sole metabolism pathway for its deactivation. Thus, understanding remimazolam hydrolysis determinants is critical for optimizing its clinical use. This study aimed to identify the enzyme(s) responsible for remimazolam hydrolysis and evaluate the impact of genetic polymorphisms and drug-drug interactions (DDIs) on remimazolam hydrolysis in human liver. We first conducted an incubation study of remimazolam with phosphate buffer saline (PBS), human serum, and the S9 fractions of human liver and intestine. Remimazolam was found exclusively hydrolyzed by human liver S9 fractions. Subsequent incubation studies with transfected wild-type carboxylesterase1 (CES1), recombinant human CES1, and carboxylesterase 2 (CES2) confirmed that remimazolam was specifically hydrolyzed by CES1 in human liver. Furthermore, in vitro studies with cells transfected with wild-type CES1 and the CES1 variant G143E (rs71647871) revealed that CES1 G143E significantly impaired remimazolam hydrolysis. Moreover, remimazolam hepatic hydrolysis was significantly inhibited by the CES1 inhibitor and substrate drugs, including simvastatin, enalapril and clopidogrel. In summary, presence of CES1 G143E or CES1 inhibitors/substrates significantly affected remimazolam hydrolysis in human liver. Therefore, CES1 genetic variants and its inhibitor/substrate drugs are crucial factors contributing to interindividual variability in remimazolam hepatic metabolism, holding the potential to serve as biomarkers for optimizing remimazolam use.