Topiramate - an efficacious new antiepileptic drug. An open prospective study

Topiramate is a new antiepileptic drug, which is not yet marketed in Germany. The anticonvulsive activity is probably mediated by sodium-channel blockade combined with gabaergic and weak antiglutamtergic properties. We investigated 23 patients with partial seizures in this open prospective study. The efficacy was analysed under stable concurrent antiepileptic drugs. Two of the patients became seizure free. Ten patients had a reduction of seizure frequency of at least 50%. The responder rate was 57%. The maximum daily dosages were 400 to 850 mg. Side-effects without relationship to dose were nervousness and aggression. In two patients an psychotic episode occurred. Dose-related side-effects were ataxia, dizziness, somnolence and dysarthria. This study is underlining that topiramate is efficacious in the treatment of partial onset seizures but also associated with a narrow therapeutic width.