Therapeutic drug monitoring for antiepileptic drugs using HPLC: An experience at a tertiary care hospital in India

This study was carried out to analyse retrospectively the data of 1,349 patients receiving antiepileptic drugs (AEDs) distributed drug wise into subtherapeutic, therapeutic, toxic and not detectable ranges. Patients were divided into three groups based on the monotherapy they received. In Phenytoin group (n=1255), 26.4% were found to be in therapeutic range, 51.6% in the subtherapeutic range and 20.6% in the toxic range. For Carbamazepine (n=63), 52.4% were in the therapeutic range, 14.3% were in subtherapeutic range, 31.7% in the toxic range and 1.6% were undetectable. Phenobarbitone levels (n=31) were found to be 64.5% in therapeutic range, 22.6% in subtherapeutic range, 9.7% in toxic range and 3.2% in the undetectable range. In 100 patients of phenytoin analyses which were under good seizure control and free of adverse effects, 46% were found to be in therapeutic range, 31% were in subtherapeutic range and 23% were found to be in toxic range. On the basis of this data, it is recommended that therapeutic drug monitoring should be carried out in all patients receiving AEDs for better overall management and long term clinical outcome.