Remifentanil Hydrochloride

Yan S, et al. determined the median effective dose (ED50) of prophylactic intravenous remifentanil for preventing rocuronium injection pain and explored the influence of age. Eighty-nine patients undergoing elective general anesthesia were stratified into three age groups (18–44, 45–59, and 60–80 years). Using the Dixon sequential method, the ED50 of remifentanil based on lean body weight was calculated as 1.266 μg/kg, 1.188 μg/kg, and 1.070 μg/kg for the youngest to oldest groups, respectively. No adverse reactions to remifentanil were observed.

Fig. 1 Study protocol (Yan S, et al., 2023)

Vellinga R, et al. conducted a three-period, crossover, dose-ranging trial involving 24 healthy volunteers to characterize the drug-drug interaction between remifentanil and remimazolam. Pharmacokinetic analysis revealed that remifentanil reduced the apparent clearance of remimazolam's active metabolite (CNS7054), with half-maximum inhibition occurring at 8.0 ng/mL. A synergistic pharmacodynamic interaction was observed across all sedation endpoints (Modified Observer's Assessment of Alertness/Sedation scale, Bispectral Index, and tolerance to laryngoscopy and tetanic stimulation). Simulations indicated optimal remimazolam target concentrations of 200–275 ng/mL when combined with remifentanil at 0–0.5 ng/mL to achieve moderate sedation.

Fig. 2 Modified Observer’s Assessment of Alertness and Sedation (MOAAS) scores versus remimazolam target concentrations stratified by remifentanil target concentrations. (Vellinga R, et al, 2025)