Double-blind study of gamma-vinyl GABA in patients with refractory epilepsy.

Twenty-four patients with frequent drug-resistant seizures took part in a randomised double-blind placebo-controlled crossover trial of the GABA-transaminase inhibitor, gamma-vinyl GABA. It was added to their usual drug treatment in a dose of 3 g daily. The total number of seizures during the 9-week active treatment period was less than that in the placebo period (p less than 0.001, two-way analysis of variance). The greatest effect was on complex partial seizures. Mean weekly seizure frequency (complex partial and tonic-clonic) was 6.2 fits/week for the placebo period and 3.5 fits/week for the gamma-vinyl GABA period. Adverse effects, particularly drowsiness and mood changes, occurred more often during administration of active drug. Serum concentrations of phenytoin were lower during gamma-vinyl GABA treatment than during placebo (p less than 0.05), but the concentrations of other anticonvulsants given concomitantly did not change. These results suggest that gamma-vinyl GABA is an effective antiepileptic compound.