[Diphenylhydantoin intoxication following the exchange of seemingly equal DPH-preparations (author's transl)]

Following replacement of diphenylhydantoin (DPH) medication by a DPH preparation of different manufacture in a 41 years old woman the patient developed in spite of identical dosage clinical symptoms of overdosage which could be confirmed by EEG and determination of serum levels. In healthy volunteers the serum levels after a single oral dose of 300 mg of Epilan D Gerot and Difhydan respectively were compared. Although both preparations contained the acid of DPH significant differences in serum levels were observed. Therefore it must be concluded that the extent of the resorption differs greatly and that galenics plays a major role with regard to the bio-availability of the drug. From this single dose study no conclusions can be drawn, however, to the serum levels in long term therapy. The early clinical manifestations as well as the value of EEG and plasma level determinations in recognition of an overdosage during DPH therapy are discussed.