Abstract
Nizatidine, a new H2-receptor antagonist, has been reported to inhibit acetylcholinesterase activity. This could lead to an interaction with neuromuscular blocking drugs. This study examined the effects of nizatidine on the actions of vecuronium. Oral nizatidine has been reported to be an effective protective agent against acid aspiration syndrome, and we reevaluated this effect.
The control group (n=10) received a placebo with water 50 ml and the nizatidine group (n=10) received nizatidine 300 mg with water 50 ml two hours before arrival in the operating room. Gastric contents were aspirated and the volume and pH measured before induction of anaesthesia. Anaesthesia was induced in all patients with thiopentone 5 mg/kg and 1.5% isoflurane in 98.5% oxygen followed by vecuronium 0.1 mg/kg. Vecuronium onset time and duration time 25 (time from injection until recovery of 25% of vaseline twitch amplitude) were obtained using electromyography.
There were no significant differences between the two groups in vecuronium onset time or duration time 25. Gastric fluid volume was greater and gastric pH was lower in the control group than in the nizatidine group. 70% of the control group and none of the nizatidine group (P<0.005) had a gastric content pH <2.5 or volume >25 ml.