INVESTIGATION ON THE SYMPATHOMIMETIC PROPERTIES OF PHENCYCLIDINE BY COMPARISON WITH COCAINE AND DESOXYEPHEDRINE.

The sympathomimetic properties of phencyclidine have been investigated by comparison with those of cocaine and desoxyephedrine in parallel experiments. Phencyclidine, like the latter two drugs, produced in pentobarbitalanesthetized dogs a slight pressor effect at the initial low doses to a depressor effect at succeeding increasing dosages. Pre-administration with phencyclidine, as with cocaine or desoxyephedrine, suppressed the pressor responses to phenethylamine and McN-A-343. Whereas both phencyclidine and cocaine potentiated the hypertensive responses to norepinephrine and DMPP, desoxyephedrine was practically indifferent. In dogs pretreated with 3-phenoxy-propylguanidine, a catecholamine-depleting agent, the pressor effects of epinephrine and DMPP were not appreciably augmented by the premedications of either phencyclidine, cocaine or desoxyephedrine. In reserpine-pretreated animals, on the other hand, the responses to norepinephrine were significantly greater following the three sympathomimetic agents, while the responses to DMPP were similar to those in animals pretreated with 3-phenoxypropyl-guanidine. In hydrated rats phencycidine resembles cocaine, desoxyephedrine, and epinephrine in promoting the excretion of urine at low doses; it differed from the latter three drugs in impeding urine excretion at high dosages. The excitatory and anticonvulsant effects of phencyclidine in mice, like those of cocaine and desoxyephedrine, were potentiated by pretreatment with iproniazid. A discussion is given of the possible mode and site of action of phencyclidine on the central nervous system from the similarity in sympathomimetic characteristics to those of cocaine and desoxyephedrine.