Abstract
Effect of 1-(m-chlorophenyl)-3-N, N-dimethylcarbamoyl-5-methoxypyrazole (PZ-177) (62.5 and 250 mg/kg) on rat liver was investigated by measuring liver weight and drug-metabolizing enzyme activity. The effects of PZ-177 were compared with those of phenobarbital, phenylbutazone, and tiaramide hydrochloride. Increase of liver weight and liver/body weight ratio was observed in the rats treated with PZ-177 or phenobarbital, however, normal values were reverted to 1-2 weeks after treatment. PZ-177 similar to phenobarbital, significantly enhanced the activity of aminopyrine demethylase and aniline hydroxylase after 1, 2, and 4 weeks of treatment. In contrast, tiaramide hydrochloride decreased the activity of aminopyrine demethylase and aniline hydroxylase after 1 week of treatment, and significantly enhanced the activity of these enzymes after 4 weeks. The content of cytochrome P-450 and the activity of NADPH cytochrome C reductase were also increased by treatment with PZ-177. The sleeping time by hexobarbital was shortened significantly by the administration of PZ-177. Vmax for both aminopyrine demethylase and aniline hydroxylase increased by treatment with PZ-177. However, only the Km for aniline hydroxylase was increased by treatment with PZ-177. From the results of these experiments, PZ-177 may be classified as a phenobarbital-type inducer.
