[Determinants of tiagabine (TGB) efficacy and safety. A Polish multicenter study of 1307 patients with focal epilepsy].

Tiagabine (TGB) is a novel anti-epileptic drug providing new therapeutic possibilities to patients with focal seizures resistant to treatment. Since there is no clear algorithm for the best add-on therapy, the aim of our work was to establish factors that statistically significantly affect tiagabine efficacy and toxicity in patients with focal seizures. Data in the study were obtained from over 200 neurologists all over Poland. A group of 1307 patients aged from 3.5 to 80 years with drug-resistant focal epilepsy participated in the study. They were under observation for 16 weeks when receiving TGB as an add-on therapy. Prior to TGB treatment they had at least 1 seizure per month (mean 7.42 +/- 9.86) during the past 3 months. On the study completion 40.47% of the patients were seizure-free for at least a month. Two factors turned out to be significant for TGB efficacy: the number of drugs used since the onset of epilepsy (p = 0.005) and seizure type (p = 0.047). The best outcome was attained in patients with simple partial seizures. Co-medication with phenytoin was better than TGB + carbamazepine or TGB + valproic acid. The factor determining the presence of side effects was the rate of TGB dose increment during the first six weeks of treatment. Toxicity of TGB was not related to its target dose. Tiagabine is a safe and efficient anti-epileptic drug for children and adults with focal epilepsy. Efficacy of tiagabine treatment depends on the number of drugs administered since the epilepsy onset and on the type of seizures. A slow dose increment is crucial for safety of TGB treatment.