Suxamethonium pains: hypothesis and observation

The muscle pains that follow the administration of suxamethonium and suxethonium have been recognised since 1952112 and although they are not a serious post-operative complication they have received considerable attention from research workers. Age, sex and the degree of physical fitness have been shown to influence the amount of pain3 and it has been shown that pre-treatment with non-depolarizing relaxants reduces the pain4. There is a widespread belief that the pain is attributable to muscle damage produced at the time of the muscle-twitch and such an hypothesis is attractive, since it is only those relaxants which produce twitching that give rise to pain. In this paper an hypothesis is put forward to explain how muscle pain arises, certain predictions are made, and these are then tested experimentally.