BackgroundAlthough remimazolam tosilate is an ultra-short-acting benzodiazepine that causes less respiratory and circulatory depression than propofol, studies evaluating its efficacy and safety during endoscopic retrograde cholangiopancreatography (ERCP) are limited. This study aimed to compare the efficacy and safety of remimazolam and propofol for ERCP performed under monitored anesthesia care (MAC). MethodsThis study is a randomized controlled clinical trial featuring a noninferiority design. A total of 102 eligible patients undergoing ERCP under MAC were randomly assigned to either the remimazolam tosilate group (R group) or the propofol group (P group) in a 1:1 ratio. Patients in the R group were sedated with remimazolam tosilate, while those in the P group received propofol, both under MAC. The primary efficacy endpoint was the success rate of ERCP completion under MAC. Secondary outcomes included the time to loss of consciousness, sedative effects, and perioperative adverse events at various time points for patients in both groups. ResultsBaseline characteristics of both groups were similar. The successful completion rate for ERCP under MAC was 100 % in the R group and 96.1 % in the P group, resulting in a difference of 3.92 % (95 % CI: −2%, 10 %). This difference met the pre-established criterion of being greater than −8%. The total number of norepinephrine infusions, as well as the incidence of intravenous injection pain, post-induction hypotension, post-induction bradycardia, intraoperative hypotension, respiratory depression, and hypoxemia, were significantly lower in the R group compared to the P group. Conversely, the total number of phloroglucinol uses, body movements, and instances of rapid gastrointestinal peristalsis were significantly higher in the R group than in the P group. DiscussionRemimazolam-based MAC for ERCP exhibited non-inferior efficacy compared to propofol-based MAC, while also resulting in fewer circulatory and respiratory adverse events during the procedures. Nevertheless, future studies with larger sample sizes are required to evaluate the utility of remimazolam in elderly patients.