Efficacy and safety of eslicarbazepine acetate as adjunctive treatment in adults with refractory partial-onset seizures: A randomized, double-blind, placebo-controlled, parallel-group phase III study

Purpose: To study the efficacy and safety of eslicarbazepine acetate (ESL) as adjunctive therapy for refractory partial seizures in adults with 4 partial-onset seizures (simple or complex, with or without secondary generalization) per 4 weeks despite treatment with 1-2 antiepileptic drugs (AEDs). Methods: This multicenter, parallel-group study had an 8-week, single-blind, placebo baseline phase, after which patients were randomized to placebo (n = 102) or once-daily ESL 400 mg (n = 100), 800 mg (n = 98), or 1,200 mg (n = 102) in the double-blind treatment phase. ESL starting dose was 400 mg; thereafter, ESL was titrated at weekly 400-mg steps to the full maintenance dose (12 weeks). Results: Seizure frequency adjusted per 4 weeks over the maintenance period (primary endpoint) was significantly lower than placebo in the ESL 1,200-mg (p = 0.0003) and 800-mg (p = 0.0028) groups [analysis of covariance (ANCOVA) of log-transformed seizure frequency]. Responder rate was 20% (placebo), 23% (400 mg), 34% (800 mg), and 43% (1,200 mg). Median relative reduction in seizure frequency was 16% (placebo), 26% (400 mg), 36% (800 mg), and 45% (1,200 mg). The most frequent concomitant AEDs were carbamazepine (56-62% of patients), lamotrigine (25-27%), and valproic acid (22-28%). Similar efficacy results were obtained in patients administered ESL with or without carbamazepine as concomitant AED. Discontinuation rates caused by adverse events (AEs) were 3.9% (placebo), 4% (400 mg), 8.2% (800 mg), and 19.6% (1,200 mg). AEs in > 10% of any group were dizziness, headache, and diplopia. Most AEs were mild or moderate. Discussion: ESL, 800 and 1,200 mg once-daily, was well tolerated and more effective than placebo in patients who were refractory to treatment with one or two concomitant AEDs.