The pharmacology of AH8165: a rapid-acting, short-lasting, competitive neuromuscular blocking drug.

l,rAzobis[3-methyl-2-phenyl-lH-imidazo(l,2-a)pyridinium] dibromide, AH 8165, produced a competitive neuromuscular block in the mouse, chick, cat, dog and monkey. The paralysis was characterized by a very rapid onset of action and, in all species except the monkey, by a short duration of action comparable to that of suxamethonium. In the monkey, the effect of AH 8165 was more persistent but was shorter than that obtained with gallamine or pancuronium. The neuromuscular block induced by AH 8165 was rapidly and completely reversed by neostigmine. Fully effective neuromuscular blocking doses of AH 8165 produced no adverse effects on blood pressure or the electrocardiogram; at much higher doses AH 8165 caused a fall in blood pressure due to a ganglion blocking action. AH 8165 did not release histamine. It is considered that AH 8165 has advantages over existing neuromuscular blocking agents and merits detailed study in clinical trial.