A new non-depolarizing myorelaxant with high activity and specificity.

The curare-like activity and mode of action of tercuronium (p,p"-bistriethylammonium-p-terphenyl dibenzen-sulphonate) have been investigated in experiments with cats, rabbits, mice and pigeons as well as with rat phrenic diaphragm preparations. The curare-like activity of tercuronium was higher than that of tubocurarine and was close to that of pancuronium bromide. The curare-like activity of tercuronium was higher than that of tubocurarine and was close to that of pancuronium bromide. The neuromuscular blocking doses (ED95) of tercuronium, (+)-tubocurarine and pancuronium in cats, for example, were 0.08 microM/kg, 0.4 microM/kg and 0.04 microM/kg respectively. The time of development and duration of action were similar to those of (+)-tubocurarine and pancuronium. Tercuronium is a nondepolarizing myorelaxant. In experiments with cats the antagonism of neostigmine (0.1 mg/kg) to tercuronium was more pronounced than in the case of (+)-tubocurarine, pancuronium or gallamine. Tercuronium affected neither the arterial pressure nor the heart rate when given in neuromuscular blocking doses. Tercuronium did not block transmission through autonomic ganglia and had no atropine-like action. Only a 10-fold increase in the dose of tercuronium produced the ganglion blocking effect in cats. Under artificial respiration, cats and rabbits tolerated tercuronium in a dose 200 times exceeding its myoparalytic dose. It is concluded that tercuronium is distinguishable from (+)-tubocurarine by its high neuromuscular blocking activity as well as by its specificity and more pronounced neostigmine antagonism.