Passage of diphenylhydantoin across the placenta

To the Editor:— The levels of diphenylhydantoin in the plasma of a young epileptic mother, in cord blood, and in the serum of her healthy newborn son were essentially equal, indicating that diphenylhydantoin freely crosses the placental barrier. The infant's serum levels suggest a first-order disappearance of diphenylhydantoin and a biological half-life of approximately 19 hours. It is known that diphenylhydantoin crosses the placenta but to our knowledge, there have been no definitive studies reporting diphenylhydantoin levels in newborn infants.1The current study demonstrates that diphenylhydantoin freely crosses the placenta reaching equilibrium in the maternal and fetal blood. Methods and Materials.— A 19-year-old gravida 1, para 0, white woman gave birth to a healthy, 3,075 gm (6 lb 12 1/2 oz) male child at 8:15 p.m., May 12,1969. Diphenylhydantoin, 100 mg four times a day, had been prescribed for her upon the diagnosis of a seizure disorder in November