Felbamate Monotherapy: Implications for Antiepileptic Drug Development

Summary: We studied the effect of felbamate (FBM) monotherapy on seizure rate in patients with partial and secondarily generalized seizures undergoing presurgical monitoring at a single site. The study design was a double-blind placebo-controlled parallel monotherapy trial. Forty patients whose seizures had not been controlled by standard antiepileptic drugs (AEDs) were randomized. Seizure type was confirmed by video-EEG monitoring. All baseline AEDs were discontinued, and patients were drug-free for 5.3 ± 2.4 days before randomization to FBM or placebo. After a 4-day titration, seizures were counted for 14 days. Patients receiving FBM had significantly lower seizure rates, whether all randomized patients, patients who survived titration, or study completers were compared. Eight of 19 placebo patients randomized to placebo, as compared with 13 of 21 receiving FBM, completed the 18-day study. Two FBM patients dropped out due to seizures, and 6 dropped out due to side effects, including anxiety, difficulty sleeping, abdominal discomfort, acute psychosis, and orobuccal dyskinesias. Ten placebo patients met the criteria for premature discontinuation owing to seizures, and 1 had an episode of panic. There was no evidence of hepatic or hematologic toxicity. FBM reduces seizure frequency in patients with localization-related epilepsy.