Once-daily extended-release levetiracetam as adjunctive treatment of partial-onset seizures in patients with epilepsy: a double-blind, randomized, placebo-controlled trial.

Purpose: Double-blind randomized trial to assess efficacy and tolerability of once-daily extended-release levetiracetam (LEV XR) tablets (2 x 500 mg) as add-on therapy in patients (12 70 years old) with partial-onset seizures (POS) refractory to one to three antiepileptic drugs. Methods: After an 8-week prospective baseline-period, eligible patients were randomized (1: 1) to once-daily LEV XR 1,000 mg/day or placebo for 12 weeks. Evaluations included changes from baseline in POS-frequency/week, responders (>= 50% reduction in POS-frequency/week), seizure-freedom, adverse events, laboratory tests, physical and neurologic examinations, vital signs, body-weight, and 12-lead electrocardiogram. Results: Of 188 patients screened, 158 were randomized (intention-to-treat population): LEV XR (n = 79) or placebo (n = 79). Seventy-one (89.9%) LEV XR and 72 (91.1%) placebo patients completed the trial. Median POS-frequency/week reduction was 46.1% on LEV XR and 33.4% on placebo. Estimated reduction with LEV XR over placebo was 14.4% (p = 0.038). Thirty-four (43%) LEV XR and 23 (29.1%) placebo patients experienced >= 50% reduction in POS-frequency/week. Eight (10.1%) patients receiving LEV XR and one (1.3%) receiving placebo were free of POS during the 12-week treatment period. Forty-one (53.2%) LEV XR and 43 (54.4%) placebo patients reported 1 adverse event. Adverse events reported with an incidence >5% and seen more often with LEV XR than with placebo were somnolence, influenza, irritability, nasopharyngitis, dizziness, and nausea. Discussion: Once-daily LEV XR 1,000 mg was effective and well-tolerated as adjunct therapy in patients with POS. Ten percent of patients randomized to LEV XR experienced freedom from POS. These results support the clinical value of this new LEV XR formulation.