METABOLIC DEMETHYLATION OF 3-METHYL-5-ETHYL-5-PHENYL HYDANTOIN (MESANTOIN)

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

After administration of 3-methyl-5-ethyl-5-phenyl hydantoin (Mesantoin) to dogs and to men, 5-ethyl-5-phenyl hydantoin (Nirvanol) has been isolated from the urine.

Comparison of the excretion of Nirvanol by the dog when Mesantoin and when Nirvanol itself are administered indicates that demethylation of Mesantoin is substantially complete in that animal.

The optical isomers of Nirvanol are excreted in unequal amounts. In dog urine there is a slight preponderance of the levorotatory isomer, whether Mesantoin or Nirvanol is administered. The Nirvanol excreted by men receiving Mesantoin consists very largely of the levorotatory isomer.

The extent to which the therapeutic and toxic effects of Mesantoin can be attributed to the Nirvanol produced from it is discussed.