The effect of ipriflavone and its major metabolites, 7-hydroxy-isoflavone and 7-(1-carboxy-ethoxy)-isoflavone on theophylline metabolism was examined in vitro in human liver microsomes. The compounds inhibited the N-demethylation to 1- or 3-methylxanthine, the major pathway of theophylline metabolism. The effect showed concentration dependence. The oxidation of theophylline to 1,3-dimethyluric acid was slightly affected by ipriflavone and its metabolites and the effect was non-specific. Results indicate that the reduction of theophylline clearance by concomitant ipriflavone administration observed by Takahashi et al. is primarily due to an interaction of the inhibitory ipriflavone and/or its metabolites with cytochrome P450 enzyme(s) that mediate N-demethylation of theophylline.
|Number of pages||6|
|Journal||European Journal of Drug Metabolism and Pharmacokinetics|
|Publication status||Published - Jan 1 1996|
ASJC Scopus subject areas
- Pharmacology (medical)