Efficacy and Safety
Three similar randomized, placebo-controlled phase 3 trials of eslicarbazepine acetate were completed, including a total of 1049 patients. Compared with placebo, once-daily eslicarbazepine acetate reduced seizure frequency at doses of 800 mg/day (P < .0001) and 1200 mg/day (P < .0001). The median relative seizure frequency reduction was 35% (800-mg/day dose) and 39% (1200-mg/day dose). Responder rates were 22% (placebo), 36% (800-mg/day dose) and 44% (1200-mg/day dose).
The most common adverse events (> 10%) were dizziness, somnolence, and headache. Adverse events were dose-related. Unlike with carbamazepine and oxcarbazepine, the incidence of rash was low -- approximately 1%. There was also a low incidence of behavioral or psychiatric adverse events, with no cases of suicide attempt or suicide. The most common side effects leading to treatment discontinuation were dizziness, vomiting, nausea, diplopia, somnolence, abnormal coordination, and headache.
Adjunctive Treatment
In the phase 3 clinical trials, there was no difference in efficacy in patients who were taking concomitant carbamazepine, lamotrigine, or valproic acid. However, combined treatment with carbamazepine, but not lamotrigine or valproic acid, increased the incidence of diplopia, abnormal coordination, and dizziness. Carbamazepine also increased the clearance of eslicarbazepine. Patients taking oxcarbazepine were not included in the trials. Consequently, it may be prudent not to combine eslicarbazepine with either carbamazepine or oxcarbazepine.