Failure of two benzodiazepines to prevent suxamethonium-induced muscle pain.

In a randomised double-blind trial carried out on fit, unpremedicated patients undergoing standard minor operations with early postoperative mobility, using a standard form of anaesthesia, pretreatment with diazepam 0.15 mg/kg or midazolam 0.1 mg/kg failed to reduce significantly the incidence of postoperative muscle pains following suxamethonium 1 mg/kg. By contrast, tubocurarine 0.05 mg/kg proved to be effective as a pretreatment. Neither benzodiazepine influenced the incidence or severity of fasciculations seen with suxamethonium or the duration of neuromuscular block. Tubocurarine virtually abolished visible fasciculation and, in the dose used, reduced the intensity and duration of the neuromuscular block. There were no clinically significant changes in serum potassium, creatinine phosphokinase or aldolase after suxamethonium, although 5 out of 47 showed an atypical rise in creatinine phosphokinase.