Gabapentin add-on treatment: how many patients become seizure-free? An open-label multicenter study

The aim of the study was to find out the percentage of patients with localization-related epilepsy achieving complete seizure control with gabapentin (GBP) add-on therapy. Patients under anti-epileptic drug monotherapy during 8 weeks baseline (BSL) with 6 or more seizures were treated with GBP for 26 weeks up to 2400 mg/day. Patients obtaining complete seizure control of all seizures or any partial seizure type during the last 8 weeks were calculated. Seizure frequency was compared between BSL and last 8 weeks. In all, 110 patients were enrolled (92 completed, 18 discontinued): mean age of the completers: 37.6 years (range 16-72), median seizure frequency per 28 days at BSL: 6.8 (2.5-24.5), mean duration of epilepsy: 17.6 years (0.2-51.4), mean duration with GBP for completers: 182.8 days (144-187). Complete seizure control of all seizures was achieved in 8.7% of patients (simple partial seizures: 13.3%, complex partial seizures 24.3%, secondarily generalized seizures: 61.5%): 38% of the patients became seizure-free in at least 1 seizure-type; 40% experienced adverse events. Assessment for quality of life (QoL) and trough plasma levels of GBP did not correlate with the good effect of GBP.