Single-blind, placebo-controlled multicenter trial of vigabatrin in the treatment of epilepsy. The Italian Study Group on Vigabatrin.

A single-blind, placebo-controlled multicenter trial of vigabatrin was carried out in 101 epileptic patients (mostly with partial seizures) refractory to conventional therapy. The study design included four consecutive periods: (i) an observation phase (run-in), (ii) a placebo period, (iii) fixed-dosage add-on vigabatrin (2 g/day) and (iv) dose titration (up to a maximum of 4 g/day) to optimize clinical response. Each period lasted 8 weeks, except for the titration phase, which could be extended to 16 weeks. 90 patients completed the trial. Eleven dropped out, one patient developing absence status and 4 cases showing an increased seizure frequency. In the patients completing the trial, the median number of seizures/month decreased from 16 (inter-quartile range 8-34) during placebo to 5 (2-10) during the last 8 weeks on vigabatrin (p < 0.0001). Both partial and generalized tonic clonic (mostly secondary) seizures were significantly reduced. A greater than 50% reduction in seizure frequency (compared to placebo) was observed in 60 patients. Sedation and weight gain were the most frequently reported adverse events.