Phenytoin is one of the most widely prescribed antiepileptic drugs (AEDs) in the USA (approximately 52% of AED prescriptions compared with 19% for valproic acid, 11% carbamazepine, and 7% phenobarbital) [1]. It has a narrow therapeutic range and wide interindividual variability in clearance and, as such, therapeutic drug monitoring is often necessary. Adverse effects of phenytoin range from min...
