Guidance for interactions between antiseizure medications.

History of antiseizure medications (ASMs) starts in 1857, with introduction of bromides in clinical practice, and nowadays about 30 drugs with anticonvulsant properties are available [1,2]. ASMs are frequently prescribed in clinical practice since prevalence of epilepsy in general population is about 1%, and there are other approved indications for ASMs, like bipolar disorder, neuralgia, or neuropathy [3]. Co-prescribing of two or more ASMs occurs in about 25% of children and 59.6% of adolescents and adults, typically with more severe types of epilepsy [4,5]. If at least one of co-administered ASMs has narrow therapeutic window [6], pharmacodynamic or pharmacokinetic interactions between them are more likely to be clinically relevant, resulting either with changes in therapeutic effect (augmentation or diminution), or with potentiation of adverse effects. Sometimes ASMs are deliberately combined, taking advantage of the pharmacodynamic interaction and augmentation of antiseizure effect, but this may require dose adjustment due to simultaneous pharmacokinetic interaction. Knowledge of the main principles of avoiding (or utilizing) drug–drug interactions (DDIs) between the ASMs should be of practical help when prescribing combinations of these drugs.