Effect of hydralazine on hepatic drug metabolizing enzymes in rats

The effects of hydralazine on hepatic drug metabolizing enzymes were studied in rats. Hydralazine inhibited aminopyrine N-demethylase and aniline hydroxylase in vitro. Kinetic studies indicated that the inhibitory natures of hydralazine were recognized as almost mixed types and a change in difference spectrum demonstrated that hydralazine could bind to cytochrome P-450 as a characteristic type II. A single administration of hydralazine inhibited the drug metabolism, but neither reduction nor induction of the mixed function oxidase system were observed after the hydralazine treatment for 7 days, except the reduction of cytochrome b5 content. In addition, acidophilic degeneration and the formation of acidophilic bodies in liver cells by hydralazine were observed.