Therapeutic drug monitoring of phenytoin using high performance liquid chromatography in a tertiary care hospital of Kashmir, India

Abstract

Background: Phenytoin is the most commonly used anti-epileptic drug (AED) in this set up due to cost effectiveness and easy availability. Significant fluctuations in serum phenytoin levels leading to toxicities or treatment failures make it an ideal candidate for therapeutic drug monitoring (TDM).Methods: Patients of age ≥18 years who were put on phenytoin were enrolled in this study. Estimation of serum phenytoin levels was done using HPLC. Data was analysed using SPSS version 20.0. Chi square test, Kruskal Wallis test were used to analyse the data.Results: A total of 105 patients enrolled in the study, twenty patients (19%) had normal or therapeutic serum phenytoin levels. Thirty-nine patients (37.2%) had sub therapeutic serum phenytoin levels, while forty-six patients (43.8%) had toxic serum phenytoin levels.Conclusions: The TDM of phenytoin should adopt a multi-disciplinary approach with active involvement of neuro-physicians, pharmacologists, pharmacists and other technical staff for improving the overall management of epilepsy. TDM data will provide the clinicians with greater insight into the factors determining the patient’s response to drug therapy.