The pharmacodynamics of alcuronium in the elderly

Alcuronium (0.2 mg/kg) was given to 12 elderly patients, mean age 77 years (range 70-88 years) and 12 young patients, mean age 24 years (range 18-32 years) undergoing general anaesthesia. A compound muscle action potential was monitored continuously throughout anaesthesia, using an electromyograph and the train-of-four twitch technique. The rate of onset and maximum block achieved were similar in both the young and elderly patients, as were the times to 20% recovery of the first twitch compared with control (T1 : T0) and fourth twitch compared with the first, (T4 : T1). In contrast, the time to 70% recovery of T1 : T0 was significantly prolonged in the elderly (138 as compared with 89 minutes: p less than 0.01) as was the recovery index (25-75%) for T1 : T0 (95 as compared with 46 minutes: p less than 0.01) and the time to 70% recovery of T4 : T1 (181 as compared with 131 minutes: p less than 0.05). The recovery curves for T1 : T0 and T4 : T1 were also significantly different in the elderly from the young group (p less than 0.01 in both instances). These results show that the duration of action of alcuronium is significantly prolonged in the elderly.