Genetic polymorphisms associated with antiepileptic metabolism.

Several factors, including pharmacogenetics, contribute to inter-individual variability in drug response. Many antiepileptic drugs (AEDs) are metabolized by a variety of enzymatic reactions, and the cytochrome P450 (CYP) family has attracted considerable attention. Some of the CYPs exist as genetic (allelic) variants, which may also affect the plasma concentrations or drug exposure. Regarding the metabolism of AEDs, the polymorphic CYP2C9 and CYP2C19 are of particular interest. There have been recent advances in discovering factors such as these, especially those underlying the risk of medication toxicity. This review summarizes the evidence about whether such polymorphisms affect the clinical action of AEDs to facilitate future studies on the pharmacogenetics of epilepsy. We performed Key Words searches in the public databases PubMed, Medscape, and Rxlisty, Pharm GKB for genetic polymorphisms and the NCBI website for the nomenclature of alleles of CYP450, finding that CYP2D6, CYP2C9, CYP3A4, and CYP2D19 were involved in the metabolism of most antiepileptic drugs, given the allele frequency in the population and the associated variability in the clinical response.