Abstract: AIM: To determinate the median effective dose (IED₅₀) of rocuronium via tracheal intubation in different ages male patients by sequential experimental method, and study the effect of the age to IED₅₀. METHODS: 40 patients(ASA grade Ⅰ or Ⅱ) scheduled for selective surgical procedure under general anaesthesia were studied. The patients were divided into two groups, young men group(n =20) and older men group(n =20). The tracheal intubation dose was divided into four grades by geometric progression growth, 0.35, 0.42, 0.5, 0.6 mg/kg in the young men group and 0.31, 0.37, 0.44 and 0.53 mg/kg in the older men group. The IED₅₀ and 95 % confidence interval (95 %CI) of rocuronium during intubation in either group was determined by sequential experimental method. RESULTS: IED₅₀ was 0.4502 mg/kg in the young men group, which was 0.4039 mg/kg in the older men group. The IED₅₀ in the older women group was 89.7 % of that in the young women group(P <0.05). The concentration of plasma total protein and albumin in the oldermen group was lower than that in the young men group (P <0.05). CONCLUSION: Sequential experimential method is a simple, efficient and reliable method for the IED₅₀ determination of rocuronium during intubation. The IED₅₀ was lower in the older men group than that in the young men group, which is possibly related to the difference of the concentration of plasma total protein in different ages male patients.

Key words: androstanols, sequential experimental method, median effective dose, age