www.ijbcp.com International Journal of Basic & Clinical Pharmacology | May 2019 | Vol 8 | Issue 5 Page 995 IJBCP International Journal of Basic & Clinical Pharmacology Print ISSN: 2319-2003 | Online ISSN: 2279-0780 Original Research Article Therapeutic drug monitoring of phenytoin using high performance liquid chromatography in a tertiary care hospital of Kashmir, India Mohd Adil*, Sameena Farhat, Mohd Younis Rather INTRODUCTION Therapeutic drug monitoring (TDM) is the clinical process of measuring the level of particular drugs at defined intervals to maintain a constant concentration in patients body fluids (plasma, serum or saliva), thus helping in the optimisation of individual drug therapy. Primarily TDM has a role in drugs with narrow therapeutic indices and marked pharmacokinetic variability. TDM is based on the assumption that there is a significant relationship between dose and body fluid concentration, and between concentration and therapeutic effects. 1 Phenytoin is one of the most widely prescribed first line antiepileptic agents in the Indian population. 2 Phenytoin (PHT) is used in the treatment of primary or secondary generalized tonic-clonic seizures, partial or complex partial seizures and status epilepticus. 3 It is the most commonly prescribed AED in this set-up due to its cost effectiveness and easy availability. 4,5 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. Keywords: Epilepsy, HPLC, Phenytoin, TDM DOI: http://dx.doi.org/10.18203/2319-2003.ijbcp20191590 Department of Pharmacology, Government Medical College, Srinagar, Jammu and Kashmir 190010, India Received: 22 February 2019 Accepted: 20 March 2019 *Correspondence to: Dr. Mohd Adil, Email: shahadil05@gmail.com Copyright: © the author(s), publisher and licensee Medip Academy. This is an open- access article distributed under the terms of the Creative Commons Attribution Non- Commercial License, which permits unrestricted non- commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.