Long-term study of gamma-vinyl GABA in the treatment of epilepsy.

The purpose of this study was to investigate the long-term efficacy and tolerability of gamma-vinyl GABA (GVG) in the treatment of epilepsy. 36 patients with severe therapy resistant epilepsies participated, the majority exhibiting complex partial seizures. The mean follow-up period was 9.3 months. GVG was administered as add-on therapy, to keep serum levels of concomitant treatment constant. The mean dose of GVG was 2.6 g's per day. Fifty-six per cent of the patients, including three patients with juvenile myoclonic epilepsy, experienced more than a 50% reduction in seizure frequency. No signs of tolerance development to the antiepileptic effect of GVG was demonstrated. Two patients were withdrawn from GVG treatment due to increased seizure frequency, and two due to side effects in the form of vomiting and nausea. Incidentally, the side effects observed were harmless and transient. Fifty per cent of the patients experienced no side effects at all. GVG seems to be a valuable antiepileptic compound. The results of this long-term study confirm observations from several short controlled trials.