Therapeutic antiepileptic drug monitoring pattern in a tertiary care hospital in Oman

In epilepsy, therapeutic drug monitoring (TDM) could aid in individualizing dosage regimen and ascertaining compliance on anti-epileptic drugs (AEDs). The aim of this study was to survey the requests for TDM of AEDs to determine drugs involved, observed concentrations, reasons for requests and action undertaken. TDM requests for AEDs were surveyed at a university hospital in Oman from January 2006 to December 2009. A total of 151 patients with 354 TDM requests were collected. These requests were for valproic acid (46.9%), phenytoin (26.8%), carbamazepine (25.4%) and phenobarbital (0.8%). 50, 37 and 13% of all reported concentrations were below, within and above therapeutic range, respectively. For majority of the subjects (70%), there were no clear reasons for plasma concentrations to lie outside the therapeutic range. No change in the drug therapy/dosing was required subsequent to the TDM reports in 42.7% of the cases. Emergency department was the main unit requesting TDM (63.8%) and TDM was mostly indicated for an increase in the seizures frequency on the same day (62.7%). This study provides an overview of the specific requests for TDM of AEDs in routine clinical practice which might help in auditing and improving this service for optimal utilization.