Suxamethonium Midazolam

In 113 patients undergoing general anesthesia, intravenous midazolam 15 mg slowed recovery of the twitch height after vecuronium and atracurium compared with diazepam. The recovery index was not altered (162). However, in another study in 20 patients, midazolam 0.3 mg/kg did not affect the duration of blockade, recovery time, intensity of fasciculations, or adequacy of relaxation for tracheal intubation produced by suxamethonium 1 mg/kg, nor the duration of blockade and adequacy of relaxation for tracheal intubation produced by pancuronium 0.025 mg/kg in incremental doses until 99% depression of muscle-twitch tension was obtained (161). Furthermore, in 60 patients undergoing maintenance anesthesia randomly assigned to one of six regimens (etomidate, fentanyl, midazolam, propofol, thiopental plus nitrous oxide, or isoflurane plus nitrous oxide), midazolam did not alter rocuronium dosage requirements (165). 

Susceptibility factors and prophylaxis Although malignant hyperthermia is usually associated with the muscle relaxant suxamethonium, all inhalational anesthetics have been implicated and will be unsafe if risk factors for this condition are present, for example a family history or one of the congenital muscle disorders (76). This must be considered in patients at risk, as there are readily acceptable alternatives, such as propofol (77) and midazolam (78). 

In other studies diazepam was found to have no significant effect on the neuromuscular blockade due to alcuronium, atracurium, gaiiamine, pancuronium, suxamethonium " or tubocurarine. " " Lo-razepam and lormetazepam have been reported to have little or no effects on atracurium or vecuronium, and midazolam has been reported to have no eftect on suxamethonium or pancuronium. ... 

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