The role of the non-depolarizing drugs in the prevention of suxamethonium bradycardia.

Evidence has been presented to show that a second dose of suxamethonium is capable of producing a severe bradycardia in man. This response may be effectively prevented by the prior administration of certain non-depolarizing muscle relaxants namely tubocurarine, alcuronium, c-toxiferine and pancuronium in quantities of one-quarter or less of their muscle relaxant level. It is suggested that suxamethonium causes altered cardiac rhythm by stimulation of afferent vagal receptors, which action may be blocked by tubocurarine and similar drugs.