ED50 and ED95 of remimazolam for loss of consciousness in young children: a dose-finding study for induction of anaesthesia.

Abstract

The optimal single i.v. bolus dose of remimazolam for induction of general anaesthesia in children is not defined. We aimed to determine the 50% (ED50) and 95% (ED95) effective doses of remimazolam for inducing loss of consciousness in children. A total of 120 children, aged 1-12 yr, were divided into three groups, with 40 children in each group: toddler (1 to <3 yr), preschool (≥3 to <6 yr), and school-age group (≥6 to <12 yr). Each child received a single i.v. bolus of remimazolam, with doses determined using a biased coin design up-and-down method. The primary outcome was the ED50 and ED95 of remimazolam for inducing loss of consciousness. Secondary outcomes included the incidence of hypotension, respiratory depression, and adverse events. The ED50 and ED95 of remimazolam were 0.42 mg kg^-1 (95% confidence interval [CI] 0.37-0.44) and 0.57 mg kg^-1 (95% CI 0.48-0.59), respectively, in the toddler group; 0.41 mg kg^-1 (95% CI 0.35-0.47) and 0.57 mg kg^-1 (95% CI 0.50-0.59), respectively, in the preschool group; and 0.30 mg kg^-1 (95% CI 0.28-0.34) and 0.43 mg kg^-1 (95% CI 0.37-0.44), respectively, in the school-age group. No significant cases of hypotension, respiratory depression, bradycardia, or other adverse events occurred in any of the three groups. A single i.v. bolus of remimazolam at estimated doses of 0.45-0.60 mg kg^-1 for children aged 1-6 yr and 0.35-0.45 mg kg^-1 for those aged 6-12 yr effectively induces loss of consciousness in children. ClinicalTrials.gov (NCT06061159).