Previous results showed that adjunctive cenobamate significantly decreased focal seizure frequency.

Adults with poorly controlled focal seizures who had ≥3 seizures/28 days despite treatment with stable doses of 1-3 AEDs were enrolled. Patients were randomized to placebo or cenobamate 200 mg/day (C013) or to placebo or cenobamate 100 mg/day, 200 mg/day, or 400 mg/day (C017). Following the 6-week titration period, patients entered a 6-week (C013) or 12-week (C017) maintenance phase. Time to first seizure was compared for cenobamate- and placebo-treated patients, as well as a moving average of seizure frequency reduction during sequential 4-week intervals (Week 1-4, Week 2-5, etc).

In C013, 109 patients were randomized to placebo, 113 to cenobamate 200 mg. In C017, 108 patients were randomized to placebo and 108, 110, and 111 to 100, 200, and 400 mg cenobamate, respectively. The mean time to first post-dose seizure was 13.9 days for 200-mg cenobamate (n=113) and 8.8 days for placebo (n=108) in C013; and 14.7 days for all cenobamate groups (n=293) and 6.4 days for placebo (n=97) in C017. In the C013 200-mg-cenobamate group, seizure frequency was reduced a median 40.6% from baseline in the first 4 weeks of treatment compared to 14.3% for placebo, followed by greater reductions from baseline over each subsequent 4-week interval for cenobamate. In C017, seizure frequency was reduced with cenobamate by a median 45% (100 mg) and 50% (200 and 400 mg) from baseline in the first 4 weeks, compared to 17% for placebo. Median percentage seizure frequency reduction continued to improve during Weeks 4-8 with cenobamate 400 mg (82%).