AN EFFECT OF PHENOBARBITONE ON GRISEOFULVIN METABOLISM IN THE RAT.

Prior administration of phenobarbitone to male and female rats dosed orally or intravenously with griseofulvin caused a fall in blood levels of the antibiotic. The effect of a single oral dose of phenobarbitone was significant after 12 hr and maximal between 12 and 48 hr, and it lasted for at least 96 hr; it was more pronounced when the barbiturate was administered repeatedly. Liver slices from animals dosed with phenobarbitone metabolized griseofulvin more rapidly than did those from undosed animals. The possible relevance of these findings to the clinical use of griseofulvin is discussed.