Phenytoin metabolism in the cat after long-term oral administration.
The metabolism of sodium phenytoin (PHT) in the cat was studied by gas-liquid chromatographic analyses of the drug and its metabolites extracted from plasma, urine, and feces during a 5-month course of daily oral administration. Plasma PHT levels of 15-18 micrograms/ml were observed. Urine contained 5-(4-hydroxyphenyl)-5-phenylhydantoin, 5-(3,4-dihydroxy-1,5-cyclohexadien-1-yl)-5-phenylhydantoin, 1-deoxy-1-(5,5-diphenylhydantoin-3-yl)-beta-D-glucopyranuronate, and unmetabolized PHT. Large quantities of PHT (32-63% of the daily dose) were observed in feces. We suggest that gastrointestinal malabsorption, extensive N-glucuronidation, and limited hydroxylation determine the fate of orally administered PHT in the cat. This is not the case in humans.
D000284:Administration, Oral; D000818:Animals; D002415:Cats; D005243:Feces / Q000032:analysis; D005260:Female; D008297:Male; D010672:Phenytoin / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000097:blood / Q000378:metabolism* / Q000652:urine
C001419:hydroxyphenytoin; C012438:5-p-methylphenyl-5-phenylhydantoin; D010672:Phenytoin