Median Effective Dose of Rocuronium for the Prevention of Succinylcholine-induced Fasciculation：An Age-Stratified Study

Background Succinylcholine, a commonly used depolarizing neuromuscular blocking relaxant, may produce fasciculation and postoperative myalgia as adverse effects. Although rocuronium pretreatment may attenuate this adverse effect, the median effective dose (ED50) remains undetermined, as does the influence of age on it. This study was carried out to determine the ED50 of prophylactic intravenous rocuronium in preventing succinylcholine-induced fasciculation and to explore the effect of age on the ED50. Methods Seventy-two adult patients undergoing elective general anesthesia were stratified according to age: Group R1 (18-44 years), Group R2 (45-59 years), and Group R3 (60-80 years). The initial dose of prophylactic rocuronium was set at 0.04 mg/kg. Midazolam 0.05 mg/kg, sufentanil 0.4 μg/kg, propofol 1.5-2.5 mg/kg, and succinylcholine 2 mg/kg were then sequentially administered 1.5 min later, then fasciculation was assessed. The rocuronium doses were adjusted according to the assessment of fasciculation using Dixon sequential method, with a ratio of 1.1 between adjacent doses. The occurrence and grades of fasciculation, adverse reactions of rocuronium, and endotracheal intubating condition were recorded. The ED50 and 95% confidence interval (CI) of rocuronium were calculated. Results The ED50 and 95% CI of prophylactic rocuronium for the prevention of succinylcholine-induced fasciculation were 0.027 μg/kg (95%CI: 0.026-0.028 μg/kg), 0.026 μg/kg (95%CI: 0.024-0.02 μg/kg), and 0.026 μg/kg (95%CI: 0.025-0.027 μg/kg) in Group R1, Group R2, and Group R3, respectively. No significant differences exist in the ED ₅₀ (95% CI) among the three groups ( P > 0.05). Only one patient experienced temporary diplopia in Group R2. No significant differences were found in fasciculation grades or endotracheal intubation conditions among the groups. Conclusion Prophylactic intravenous rocuronium can prevent succinylcholine-induced fasciculation, while its ED50 is independent of age. Clinical trial registration The study was registered at ClinicalTrials.gov (Registration number: NCT05909696) on June 10, 2023. URL: https://clinicaltrials.gov/.