Vigabatrin in chronic epilepsy: a 7-year follow-up study of responder patients.

Data on efficacy and safety of vigabatrin over very protracted treatment periods are still limited. This study reports the follow up of 23 responder epileptic patients who continued vigabatrin treatment after completion of the first year, to an overall long-term exposure ranging 21-84 months (median 60; mean 58.0 +/- 24.0 sd). The seizure frequency during the follow up was compared with that at the end of the first year on vigabatrin. The rates of patients who gained a further improvement and those who deteriorated were almost identical, ranging 33-45\% and 33-46\% respectively at individual time points. At the trial endpoint, nine patients (39\%) were improved, five (22\%) were unchanged and nine (39\%) showed some deterioration. All patients still had a 14-100\% decrease of seizure frequency as compared with pretreatment baseline. Two patients discontinued vigabatrin for occasional reasons. No patient experienced new adverse events during the follow up after the first year on vigabatrin. No significant effects were noted on any of the routine hematologic or metabolic screening assessments. Although reduction of concomitant treatment was rarely possible, the overall number of associated antiepileptic drugs dropped from 42 at entry to 40 at the trial endpoint. These findings indicate that vigabatrin retains its efficacy and safety in responder patients for periods up to 7 years.