title: A species difference in the presystemic metabolism of carbazeran in dog and man.
abstract: The bioavailability of carbazeran and the metabolism of carbon-14 labelled drug have been studied in the dog and man following oral administration. The drug was moderately well absorbed in both species, but there was a marked difference in bioavailability and in routes of metabolism. In the dog, systemic bioavailability was approx. 68% and biotransformation involved mainly O-demethylation. In man, bioavailability was not measurable and carbazeran was almost completely cleared via 4-hydroxylation of the phthalazine moiety. Thus the lack of detectable pharmacological effect in man following oral administration of the drug appears to be due to presystemic metabolism by a particularly active pathway not found in the dog.
mesh_terms: D000328:Adult; D000818:Animals; D001682:Biological Availability; D001711:Biotransformation; D002219:Carbamates / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D004285:Dogs; D006801:Humans; D008297:Male; D013045:Species Specificity
chemical_list: D002219:Carbamates; C031720:carbazeran