Vigabatrin in the treatment of epilepsy: a double-blind, placebo-controlled study.

The efficacy and tolerability of vigabatrin (gamma-vinyl GABA, GVG), given as add-on therapy to 23 adult outpatients with severe drug-resistant epilepsy (17 with partial seizures), were studied using a double-blind, placebo-controlled, crossover design. The study consisted of two 7-week periods during which vigabatrin and placebo were administered in random sequence. Dosage was 1.0 g twice daily for patients weighing less than or equal to 65 kg and 1.5 g twice daily for patients weighing greater than 65 kg. Three patients were dropped from the study, two for reasons unrelated to treatment and one because of the appearance of vertigo, headache, dysarthria, and ataxia, which subsided rapidly when vigabatrin was stopped (3 g daily). Sixteen of the 20 patients available for analysis showed a decrease in the total number of seizures as compared with the placebo period. Of these, 12 showed a greater than 50% reduction in seizure frequency and 4 of the 12 showed a greater than 75% reduction. Both the total number of seizures and the number of partial seizures were significantly reduced by vigabatrin (p less than 0.01). Only in the patient who dropped out were severe adverse effects seen. The most frequently reported unwanted effect was mild drowsiness, which developed in seven patients on vigabatrin and in one on placebo. Positive effects, however, were also seen with six patients who reported an improved sense of well-being while receiving vigabatrin as compared with only 1 during the placebo period. No consistent changes in electrocardiogram (ECG), electroencephalogram (EEG), and visual-, auditory-, and somatosensory-evoked potentials were seen during the study.(ABSTRACT TRUNCATED AT 250 WORDS)