Effects of cholinesterase inhibitors on the neuromuscular blocking action of suxamethonium

Prolonged neuromuscular block occurs when suxamethonium is givenafter neostigmine or pyridostigmine; however, studies of edrophoniumand suxamethonium have yielded conflicting results. We havestudied, therefore, interactions between suxamethonium and allthree anticholinesterases in rats anaesthetized with pentobarbitone.After recovery from an initial bolus of suxamethonium, saline,edrophonium, pyridostigmine or neostigmine was administeredand a second dose of suxamethonium was then given. All threeanticholinesterases prolonged the duration of neuromuscularblock (90% suppression to 50% twitch recovery) to 127(SEM 9)%,127(10)% and 138 (11)% of baseline for edrophonium, pyridostigmineand neostigmine, respectively. Recovery index (25% to 75% twitchrecovery) was increased also to 125 (9)%; 149 (10%) and 185(15)% of baseline, respectively for the three drugs. Presented in part at the 1992 annual meetings of the AmericanSociety of Anesthesiologists and the California Society of Anesthesiologists.