Introduction

Abstract

Epilepsy, which affects approximately 1% of the world’s population, is a chronic disorder that usually persists for many years and often for a lifetime. Antiseizure medications (ASMs) are the mainstay of epilepsy treatment, and complete seizure control can be achieved in the majority (65%) of newly diagnosed patients by prescribing a single ASM, and this is the ideal situation. For the remaining 35% of patients, the prescribing of polytherapy regimens (the use primarily of two ASMs but often three or four ASMs), so as to achieve optimal seizure control, is a common practice. However, for the majority of these patients, little additional benefit is achieved from the use of polytherapy ASMs as intolerable adverse effects commonly occur as a consequence of pharmacokinetic and/or pharmacodynamic interactions. Furthermore, for those patients who respond to monotherapy, they too may experience the consequences of ASM interactions as ASMs are added and withdrawn during the optimization of their monotherapy drug regimen. A further confounding factor is that since epilepsy is a chronic condition many patients will inevitably develop comorbid diseases or other debilitating conditions and disorders, which will require the coadministration of non-ASMs. In this setting, the potential for drug interactions is considerable. A further source of potential clinically significant interactions that is being increasingly recognized relates to the increasing use of over-the-counter medications and supplements, many of which have unknown constituents and inconsistent quality. Finally, ASMs are increasingly used to treat other non-epilepsy conditions such as mood disorders, migraine, and pain, thereby further increasing the possibility of combined use with other drugs.