Adjunctive antiepileptic drugs in adult epilepsy: how the first add-on could be the last.

IMPORTANCE OF THE FIELD: In adult epilepsies, incomplete seizure control under monotherapy affects approximately 20-25% of patients with idiopathic generalized epilepsies (IGE) and approximately 20-40% of patients with epilepsies with focal seizures (FE). The choice of an adjunctive therapy is therefore a common event. AREAS COVERED IN THIS REVIEW: Efficacy studies of add-on anti-epileptic drugs for adult epilepsies--approved since the early 1990s until 2008--were reviewed. An exception was made for valproate. WHAT THE READER WILL GAIN: Efficacy studies give important clues for add-on drug choice but--beyond this--we encourage physicians to consider other parameters, especially co-morbidity(ies) and special situation(s). According to clinical and pharmacological data, an original, practical approach is proposed, by which decisions are based on three main criteria, which aim to optimize patients' seizure control and quality of life. The need for drugs that act not only on 'ictogenesis' but also on 'epileptogenesis' is also discussed briefly. TAKE HOME MESSAGE: Given the increasing disposal of anti-epileptic drugs, the choice of an add-on therapy appears to be partly based on subjective criteria (physician opinions and preferences). In fact, the selection criteria can be clarified as: treatment decisions rely not only on seizure type, efficacy and tolerability profiles but also on patient-related factors.