[Acute toxicity and the central effect of 1-(m-chlorophenyl)-3-N,N-dimethylcarbamoyl-5-methoxypyrazole (PZ-177)].

In a previous paper, we reported that PZ-177 had potent anti-inflammatory and analgesic activities. In the present work, acute toxicity and action of PZ-177 on the central nervous system were tested in comparison with PZ-222, one of metabolites of PZ-177, and mepirizole. Acute toxicity of PZ-177 was slightly less than that of aminopyrine and the same as that of mepirizole in mice and rats. PZ-177 produced from sedation to loss of righting reflex with the increase of dose. At a low dose with which the righting reflex was hot lost, PZ-177 decreased spontaneous locomotion of mice in the Animex test, produced muscle relaxation in rotarod and inclined screen tests, produced sleeping-pattern in electroencephalogram of rabbit, potentiated hypnosis of barbiturates and exerted an anti-convulsive effect in mice. In these depressive effects on the central nervous system, PZ-222 was very much lower and mepirizole slightly lower than PZ-177. It would thus appear that PZ-177 has more potent analgesic, antipyretic and anti-tussive actions than do PZ-222 and mepirizole.