[Interaction between vecuronium and pancuronium].

Interaction between vecuronium bromide (VB) and pancuronium bromide (PB) with regard to a change in duration of action was investigated in 32 elective surgical patients divided into four groups. Initial and supplemental drugs were as follow; group I: VB-->VB, group II: PB-->VB, group III: VB-->PB, group IV: PB-->PB. The muscle response was quantified electromyographically. Anesthesia was induced with thiopental. VB or PB 0.08 mg.kg-1 (initial dose) was given to facilitate endotracheal intubation. Anesthesia was maintained with 66% nitrous oxide and 2% sevoflurane in oxygen. Supplemental dose (0.015 mg.kg-1) of the muscle relaxants was administered at 10% recovery of twitch height. Duration of action was defined as the interval between administration and 10% recovery. Duration of action of supplemental doses of VB was significantly longer in group II than in group I. That of PB was significantly shorter in group III than in group IV. Therefore, it should be noticed that duration of action of supplemental relaxant is largely modified by the initial one.

[Evaluation of the action of pipecuronium bromide in patients under halothane anesthesia--a comparison with pancuronium bromide regarding their neuromuscular blocking and cardiovascular effects].

Neuromuscular blocking and circulatory actions of pipecuronium bromide (PPB) were evaluated in patients under halothane-nitrous oxide-oxygen anesthesia in comparison with those of pancuronium bromide (PCB) in a multi-center cooperative study. Twitch tension of the adductor pollicis muscle was elicited by supramaximal stimulation of the ulnar nerve every 10 seconds. The study was performed according to the following 4 steps and the results were obtained. 1) Cumulative administration of 0.01 mg.kg-1 of PPB or PCB resulted in the potency ratio of 1.3:1.0 and the dose response curves of the two agents paralleled with each other. 2) With PPB 0.05 mg.kg-1 or 0.1 mg.kg-1, almost 100% block of the twitch was obtained. Both duration of action and the recovery time were shorter with 0.05 mg.kg-1 group. 3) After the first dose of 0.04 mg.kg-1 when the twitch recovered to 25% of the initial height 0.02 mg.kg-1 was given and this was repeated. Intervals between the doses showed large individual differences and no significant change was observed with repeated doses. 4) Safety of the drug. No significant change in heart rate or blood pressure was observed with PPB but with PCB a significant increase in heart rate was observed. The study revealed that PPB is slightly more potent than PCB and the duration of action is longer, but it has no untoward cardiovascular action in man under halothane anesthesia.