Background: Remimazolam, a new ultra-short-acting benzodiazepine, has been developed and approved as a general anesthetic. Recent studies have shown that remimazolam is as effective as propofol in general anesthesia. However, there have been limited investigations into the specific dosage of remimazolam needed for inducing general anesthesia. Our objective was to identify the 95% effective bolus dose (ED95) of remimazolam necessary to achieve loss of consciousness (LOC) and to establish suitable dosages for various age groups. Methods: This study enrolled patients between the ages of 20–79 years who were scheduled for surgery under general anesthesia, and were divided into a young group (ages 20–39 years), a middle-aged group (ages 40–59 years) and an elderly group (ages 60–79 years). Total 40 patients in each group were screened and analyzed. A pre-calculated remimazolam dose was administered and LOC was assessed for 3 min. We defined successful LOC as achieving loss of eyelash reflex and verbal response following remimazolam administration. This study determined the ED95 of remimazolam using a method that involved a biased coin up-and-down design. Results: The ED95 of remimazolam for initiating general anesthesia was 0.37 mg/kg (95% confidence interval [CI] 0.28–0.39) in the young group, 0.37 mg/kg (95% CI: 0.27–0.39) in the middle-aged group, and 0.25 mg/kg (95% CI: 0.20–0.29) in the elderly group. Throughout the study, none of the patients required additional medications to address hemodynamic depression. Conclusions: In this study, we focused on determining the ED95 of bolus remimazolam for general anesthesia in different age groups. Accurately determining the dosage can be beneficial to maintain stable hemodynamics during the induction process. Keywords: Age; General anesthesia; Hypnotics and sedatives; Intravenous anesthesia; Remimazolam
