Pharmacokinetics of three formulations of diphenylhydantoin in the dog

The pharmacokinetics of the sodium salt of diphenylhydantoin was studied in three healthy dogs, using three formulations, a capsule, a tablet and a suspension. The results were essentially the same for all three formulations. The serum half life after intravenous injection ranged from 3·1 to 3·6 hours before and 1·3 to 1·6 hours after a two-week period of oral treatment. The bioavailability of the formulations varied from 43 to 54 per cent. Serum levels likely to be required for canine therapy could not be maintained with any of the formulations used in this experiment.