QUANTITATIVE STUDIES OF THE PHYSIOLOGICAL DISPOSITION OF 3-METHYL-5-ETHYL-5-PHENYL HYDANTOIN (MESANTOIN) AND 5-ETHYL-5-PHENYL HYDANTOIN (NIRVANOL)

¹ Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina

An analytical method for the determination of 5-ethyl-5-phenyl hydantoin (Nirvanol) in plasma is described.

Following intramuscular injection of 3-methyl-5-ethyl-5-phenyl hydantoin (Mesantoin) in a dog, Nirvanol appeared in the plasma. The concentration of Nirvanol increased for about two days and thereafter slowly declined.

In a later experiment Nirvanol was administered intravenously to the same dog and the plasma concentration followed. Calculations based on data from the two experiments lead to the conclusion that Mesantoin is converted to a very large extent, perhaps almost completely, to Nirvanol by the dog.

Daily oral administration of Mesantoin to a dog brought about progressive accumulation of Nirvanol in the plasma.

The role of Nirvanol in the therapeutic and toxic effects resulting from administration of Mesantoin in clinical dosage schedules is discussed.