[Value of anticonvulsant level determination in the treatment of epilepsies].

Phenobarbital and diphenylhydantoin were estimated in treated epileptics. An initial measurement was made in 457 patients. 96% were taking phenobarbital and 53% diphenylhydantoin. Only 37% of the phenobarbital levels and 18% of the diphenhlhydantoin levels were in a therapeutic range. Correlations between the levels, the stability of the epilepsy and signs of overdosage are discussed. Intolerance to phenobarbital reported in some patients, which appears to be real, is not reflected by "normal" or even low blood levels. By contrast, high levels of phenobarbital appear to be well tolerated. Signs of overdosage were quasi-constant when levels of diphenylhydantoin were greater than 15 mg/1. Doses of phenobarbital and of diphenylhydantoin were altered, levels assessed and the clinical condition evaluated in 134 patients. Bringing levels to within the therapeutic range resulted in the disappearance of attacks in 55% of cases for phenobarbital and 30% for diphenylhydantoin. Reduction of doses responsible for excessively high blood concentrations (overdosage) was practically never associated with an increase in the number of attacks. This adjustment is easy for phenobarbital though much more difficult for diphenylhydantoin. In this study, therapeutic levels were 15 to 25 mg/1 for phenobarbital, and 7 to 15 mg/1 for diphenylhydantoin.