Long-term safety and efficacy of clobazam for Lennox–Gastaut syndrome: Interim results of an open-label extension study

Abstract In an ongoing open-label extension (OV-1004), patients with Lennox–Gastaut syndrome who had completed 1 of 2 randomized controlled trials (OV-1002 [Phase II] or OV-1012 [Phase III]) are receiving clobazam at dosages ≤ 2.0 mg/kg/day (≤ 80 mg/day). Of 306 eligible patients from OV-1002 or OV-1012, 267 entered the open-label extension. As of the interim date, July 1, 2010, 213 patients (79.8%) had remained in the trial, and 189 had received clobazam for ≥ 12 months, 128 for ≥ 18 months, and 94 for ≥ 24 months. Median percentage decreases in average weekly rates of drop seizures were 71.1% and 91.6% at Months 3 and 24. Mean modal and mean maximum daily dosages were 0.94 mg/kg and 1.22 mg/kg for those who had received clobazam for ≥ 1 year. The 4 most common adverse events were upper respiratory tract infection (18.4%), fall (14.2%), pneumonia (13.9%), and somnolence (12.7%). Clobazam's adverse event profile was consistent with its profile in controlled trials.