Antagonists to neuromuscular blocking agents. An experimental study.

T h : antagonism between tubocurarine and alcuronium chloride on the one hand and neostigmine, physostigmine, edrophonium and ambenonium on the other have been investigated. A quantitative measure of antagonism was obtained on the rat diaphragm preparation and it was found that in general the antagonists were more effective against alcuronium chloride than against tubocurarine. The antagonist drugs potentiated the action of acetylcholine on frog rectus muscle. The muscarinic action of ambenonium was less apparent than that of the other drugs but it caused severe reduction in amplitude of cardiac contraction and arrest in 50 per cent of the preparations. It is concluded that ambenonium is unlikely to prove a satisfactory drug for further investigation in man.