Background: The authors found no study comparing potency and duration of action of vecuronium and atracurium in healthy Chinese, so they compared the dose-response relations of vecuronium and atracurium in anesthetized Chinese adult patients and evaluated the time-course of action of two drugs following administration of equipotent doses.
Methods: Sixty patients, ASA grade 1, aged from 17 to 50 yr, scheduled for elective plastic surgery were randomly distributed to either the vecuronium or the atracurium group. General anesthesia was maintained with 60% nitrous oxide in oxygen (N2O-O2), thiopental and fentanyl. Neuromuscular function was assessed using a accelerometer with train-of-four (TOF) stimulation at the wrist every 12 sec, and the percentage of depression of first twitch (T1) was used as the study parameter. The dose-response relations of vecuronium and atracurium were determined using the cumulative dose-response technique.
Results: The cumulative dose-response curve of vecuronium was shifted to the left in a parallel fashion compared with that of atracurium. As assessed by linear regression, the potency ratio of vecuronium:atracurium was 6:1. There were significant differences in the ED50, ED90, and ED95 between the two drugs. After the intravenous administration of equipotent doses of both drugs (1.5 x ED95), the duration of peak effect, clinical duration, recovery index, and total duration were not significantly different between the two drugs.
Conclusions: The neuromuscular blocking potency of atracurium is approximately 17% that of vecuronium in anesthetized Chinese adult patients. Following equipotent doses, the time course of action of atracurium is similar to that of vecuronium.