Interaction Between Muscle Relaxants

Abstract

In Japan, two groups of muscle relaxants are commonly used clinically. One of them is depolarizing relaxant; succinylcholine and the other is nondepolarizing aminosteroidal relaxants; vecuronium and pancuronium. Considering that depolarizing relaxants are basically agonist and nondepolarizing relaxants are antagonist to the nicotinic acetylcholine receptors on the motor endplate, it is not unexpected that their neuromuscular effects are mutually inhibitory. Accordingly, pretreatment with a subparalyzing dose of nondepolarizing relaxant antagonizes subsequent succinylcholine-induced neuromuscular block. However, when the sequence of administration is reversed and an intubating dose of succinylcholine was followed by a nondepolarizing relaxant, potentiation rather than antagonism of the latter block has been reported. In my presentation, this controversial interaction between succinylcholine and subsequently administered aminosteroids will be discussed.