A COMPARISON OF THE SKELETAL NEUROMUSCULAR AND AUTONOMIC GANGLION‐BLOCKING POTENCIES OF FIVE NONDEPOLARIZING RELAXANTS

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Abstract
Results from in vitro experiments on the phrenic nerve—diaphragm and the hypogastric nerve—vas deferens preparations of the guinea‐pig have been used to plot log concentration‐effect curves for skeletal neuromuscular and ganglion blockade, respectively, for (+)‐tubocurarine, pancuronium, alcuronium, gallamine and fazadinium (AH 8165). From the log concentration‐effect curves, EC50s and equipotent ratios were calculated. The order of neuromuscular blocking potency was pancuronium = alcuronium > (+)‐tubocurarine > fazadinium = gallamine. The ratio EC50 for ganglion blockade/EC50 for neuromuscular blockade was 2.3 for fazadinium, 6.7 for (+)‐tubocurarine, 22.9 for alcuronium, 24.3 for gallamine and 200.0 for pancuronium. For pancuronium and gallamine there was a range of concentrations below those producing ganglion blockade at which the response of the vas deferens to hypogastric nerve stimulation was augmented. The results are compared with some of those available in the literature, measured on other species by other methods.