THE LONG-TERM SAFETY AND EFFICACY OF GABAPENTIN (NEURONTIN(R)) AS ADD-ON THERAPY IN DRUG-RESISTANT PARTIAL EPILEPSY

This is the 2-year interim report of results from a multicenter, open- label study evaluating the long-term efficacy and safety of gabapentin (Neurontin(R)) as add-on therapy in patients with refractory partial seizures who had had a therapeutic response to gabapentin in a precedi ng 12-week double-blind trial or 12-week open-label extension. A total of 240 patients continued to receive gabapentin as add-on therapy at dosages of 600-2400 mg/day for an average of 342 days (range 10-784 da ys). Efficacy analyses compared seizure frequency during consecutive 1 2-week treatment periods with seizure frequency during the 12-week bas eline. During the nine treatment periods evaluated, the percent of pat ients with a 50% or greater reduction in seizure frequency ranged from 35% to 71%, and the median percent change in seizure frequency ranged from -33% to -60%. At the time of data cutoff, 30% of patients had wi thdrawn from the study due to lack of efficacy, and 4% due to adverse events. In 225 patient-years of gabapentin treatment in this study, CN S adverse events reported by more than 10% of patients were nystagmus, somnolence, diplopia, tremor, ataxia, and dizziness. No consistent ch anges in clinical laboratory values were associated with gabapentin. G abapentin as add-on therapy at dosages up to 2400 mg/day is safe durin g long-term treatment in patients with refractory partial seizures. Su bgroup analyses of patients who remained in the study over the long te rm confirmed that gabapentin maintained efficacy for up to 2 years.