A Retrospective Study of Therapeutic Drug Monitoring of Anti-Epileptic Drugs at a Tertiary Care Hospital in India

Background: Epilepsy is a chronic disease and the aim of drug therapy is to prevent seizures with minimal adverse effects. To achieve this, the dosage of the anti-epileptic drugs (AEDs) needs to be individualised. The present study throws light on how professionals knowledgeable in clinical epilepsy management, like neurologists and clinical pharmacologists, can use Therapeutic Drug Monitoring (TDM) to design individualised dosage regimens.

Objective: The aim of the present study was to assess the effectiveness of TDM services in enhancing patient care in epileptic patients in India.

Material and Methods: This retrospective observational study was carried out over a period of two years at a tertiary care hospital in India. TDM reports of patients regularly attending the Epilepsy and TDM OPDs at our hospital were analysed. Serum AED levels were interpreted as below, within and above the reference range. All analyses were carried out using EpiInfo version 7 and a p value < 0.05 was considered significant.

Results: A total 1016 patients with 1347 TDM requisitions were analysed. Almost 46% and 9% of all TDM requisitions were below and above the reference range, respectively. However, significantly higher proportion of TDM requisition was below reference range in the 2 or more AEDs group compared to monotherapy group. Only 36% of requisitions for suspected toxicity had serum concentration above reference range.

Discussion: The results of present study suggest the importance of routine TDM of AEDs in patients with seizures. Detection of non-compliance, toxicity and failure of adequate response because of below reference range drug levels highlights the utility of TDM of AEDs in patients with seizures.

Conclusion: TDM of AEDs is a well-established means of optimising epilepsy treatment, but inter-individual variation in clinical outcome should be kept in mind while attempting an adjustment of doses.