Abstract

Due to varied pharmacokinetic behavior and inter individual variation of phenytoin, serum level monitoring is necessary to optimize the drug therapy. The present study was designed to study the relationship between serum levels of phenytoin and different patient related factors like the dose administered, effects of age, sex, control of seizures and the influence of co-medication on the phenytoin concentration. Blood samples were collected from the selected patient group (126 patients) and analyzed using a sensitive HPLC method. Of the 111 patients receiving phenytoin as mono therapy, complete seizure control could be achieved in 80 patients. Seventy four percent of these patients had seizures completely controlled with serum phenytoin level below therapeutic range. The following are the conclusions: In the epileptic patients on monotherapy, the seizure control with phenytoin was observed in the concentration range of 3.9 to 29 μg/ml with a mean (±SD) of 11.56±13 μg/ml. Patients showing therapeutic benefit ranged with serum drug level from sub therapeutic level to toxic level indicating the reference therapeutic range (10 to 20 μg/ml) has to redefined for Indian epileptic patient population.