Efficacy and safety of oral lacosamide as adjunctive therapy in adults with partial-onset seizures

Purpose: To evaluate the efficacy and safety of lacosamide when added to 1 or 2 antiepileptic drugs (AEDs) in adults with uncontrolled partial-onset seizures, and assess plasma concentrations of concomitant AEDs to determine any potential for drug interactions. Methods: During this multicenter, double-blind, placebo-controlled trial, patients were randomized to placebo or lacosamide 200, 400, or 600 mg/day after an 8-week baseline period. Lacosamide was titrated in weekly increments of 100 mg/day over 6 weeks and maintained for 12 weeks. Results were analyzed on an intention-to-treat basis. Results: Four hundred eighteen patients were randomized and received trial medication; 312 completed the trial. The median percent reduction in seizure frequency per 28 days was 10%, 26%, 39%, and 40% in the placebo, lacosamide 200, 400, and 600 mg/day treatment groups, respectively. The median percent reduction in seizure frequency over placebo was significant for lacosamide 400 mg/day (p = 0.0023) and 600 mg/day (p = 0.0084). The 50% responder rates were 22%, 33%, 41%, and 38% for placebo, lacosamide 200, 400, and 600 mg/day, respectively. The 50% responder rate over placebo was significant for lacosamide 400 mg/day (p = 0.0038) and 600 mg/day (p = 0.0141). Adverse events that appeared dose-related included dizziness, nausea, fatigue, ataxia, vision abnormal, diplopia, and nystagmus. Lacosamide did not affect mean plasma concentrations of concomitantly administered AEDs. Conclusions: In this trial, adjunctive lacosamide significantly reduced seizure frequency in patients with uncontrolled partial-onset seizures. Along with favorable pharmacokinetic and tolerability profiles, these results support further development of lacosamide as an AED.