[Phenytoin intoxication and serum level].

The symptomatology of phenytoin intoxication was observed in 8.4% of 225 adult patients and in 9.5% of 74 children, with symptoms of cerebellar affection being noted in the majority of cases. Phenytoin concentrations were found to lie between 14.4 and 77.7 microgram/ml. Interindividual differences as to the toxic limit were quite considerable: One third of the patients showing values higher than 20 microgram/ml were free of striking clinical symptoms, and one patient tolerated a serum concentration in excess of 30 microgram/ml. On the other hand, the intraindividual toxic limit did not show any major variations: The clinical symptomatology of a patient correlated with his phenytoin serum concentration. After phenytoin withdrawal, the serum concentration dropped exponentially. The half-life periods of elimination were found to be between 72 and 122 hours.