Monitoring of drug therapy in epileptic children

Twenty children who were receiving phenytoin either alone or in combination with phenobarbitone, were monitored for their plasma steady state levels. A wide interindividual variation was observed in steady state plasma levels. Among children who were receiving only phenytoin, nearly 50% had drug levels above 10 micrograms/ml. It was observed that children with drug levels above 10 micrograms/ml exhibited good therapeutic response. Two children who were presented with acute toxicity showed drug levels above 40 micrograms/ml. Children receiving combination of phenytoin and phenobarbitone showed extreme degree of variation in drug levels which was reflective of drug interaction. In view of the wide interindividual variation in level of phenytoin and the unpredictability of interaction with other anticonvulsants, the monitoring of drug levels become mandatory.