Influence of dose on suxamethonium-induced muscle damage

We have examined postoperative muscle pain and early increasesin serum concentrations of myoglobin after administration ofsuxamethonium to see if these changes were dependent on thedose of drug. Thirty ASA I and II adult patients undergoingday-case surgery received a standard anaesthetic technique,including one of three doses of suxamethonium: 0.5, 1.5 or 3.0mg kg^–1. The incidence of postoperative myalgia and theseverity of fasciculations were greater after suxamethonium1.5mg kg^–1 than after a dose of 0.5 or 3.0 mg kg^–1.Serum concentrations of myoglobin increased in a dose-dependentmanner. Intubating conditions were significantly better withsuxamethonium 1.5 or 3.0 mg kg^–1 than with 0.5 mg kg^–1.Changes in serum concentrations of calcium and potassium weresmall and similar in the three groups. We conclude that a doseof 3.0 mg kg^–1 of suxamethonium provided a better combinationof intubating conditions and minimal postoperative myalgia thanthe two lower doses. ^*Present address for correspondence: Belfast City Hospital,Lisburn Road, Belfast BT9 7AB, Northern Ireland