Does diazepam pretreatment prevent succinylcholine-induced fasciculations?--a double-blind comparison of diazepam and tubocurarine pretreatments.

To determine the effectiveness of diazepam pretreatment in preventing succinylcholine-induced fasciculations, 61 surgical patients were randomly allocated into three groups receiving either diazepam (0.05 mg/kg), d-tubocurarine (0.05 mg/kg) or saline in a double-blind fashion. Following the induction of anesthesia with fentanyl and thiopental, a bolus dose of succinylcholine (1 mg/kg was injected 5 minutes after the pretreatment drugs. Resulting fasciculations were then graded visually. Responses to electrical simulation of the ulnar nerve, somatic motor responses to laryngoscopy and endotracheal intubation, and changes in serum levels of potassium were also evaluated. Diazepam had no effect on frequency or intensity of succinylcholine fasciculations. Fasciculations were observed in 90% of the patients given placebo injections and in 95% of those given diazepam, but in only 16% of those given tubocurarine. Tubocurarine prolonged the onset and shortened the duration of the succinylcholine block and thus made intubation more difficult. Diazepam accelerated onset, but had no effect on duration of succinylcholine block. The twitch response following ulnar nerve stimulation disappeared after 84 seconds (p < 0.01 vs placebo) in patients given diazepam after 115 seconds in patients given tubocurarine, and after 106 seconds in those given placebo injections. The increase in serum potassium after succinylcholine was prevented by pretreatment with d-tubocurarine but not by diazepam.