[Efficacy and tolerability of dose-escalation with generic gabapentin--a multicenter, non-interventional study]

The aim of this study was to determine the efficacy and tolerability of 1800-2400 mg/day of generic gabapentin (Gabapentin Teva) as add-on treatment for refractory partial - onset epilepsy. This was a multicenter, open-label, dose-escalation study of patients with refractory epilepsy (median age of 45.5 years [41-50; 25-75% percentile range], male 45.6%, female 47.8%). The inclusion criteria were insufficient partial-onset epilepsy control, defined as at least 1 seizure per month, while on adjunctive therapy with gabapentin used on daily doses below 1200 mg. The baseline seizure number was assessed over 3 months of observation in patients being on stable doses of their AED therapy and those subjects who met the inclusion criteria were enrolled into the study by their neurologist (Visit 0). Subsequently, patients were seen, and their data were evaluated at Visit I i.e. after the target dose of 1800 mg per day was achieved (mean duration of 3.6 [0.1-28.3] weeks) and 4 weeks later at Visit II, after the target dose up to 2400 mg per day. Primary efficacy was assessed by seizure frequency (number/month). Tolerability was assessed by adverse events and clinical evaluations. All the study periods were completed by 916 patients. A substantially lower median seizure frequency was observed at all gabapentin dosing periods (visit I - 2.0 [0-40] seizures per month and visit II - 1.0 [0-13] seizures per month; median and range) compared with the baseline period (3.0 [1-20] seizures per month) (Wilcoxon test p<0.001). In addition, the gradual increase of GBP dose led to raising proportion of patients rendered seizure free (Visit I - 1.1% and Visit II - 28.5%) compared with the baseline period 0.0% (McNemar test p<0.001). The dose escalation with GBP was well tolerated by the majority of patients. The most common adverse events during visit II were somnolence (2.8%) and dizziness (1.8%). In conclusion, gabapentin dose escalation to a dose range of 1800-2400 mg/d over 8 [1-32] week period proved to be an effective and well tolerated in patients with insufficient seizure control on lower doses with partial-onset epilepsy.