Efficacy and safety of adjunctive perampanel 4 mg/d for the treatment of focal seizures: A pooled post hoc analysis of four randomized, double-blind, phase III studies

Objective: This post hoc analysis evaluated the efficacy and safety of adjunctive perampanel 4 mg/d received as modal dose, which may have differed from randomized dose, for treatment of focal seizures.

Methods: Data were pooled from four randomized, double-blind, placebo-controlled, phase III studies of adjunctive perampanel in patients (aged ≥12 years) with focal seizures, with/without focal to bilateral tonic-clonic (FBTC) seizures: studies 304 (NCT00699972), 305 (NCT00699582), 306 (NCT00700310), and 335 (NCT01618695). Efficacy assessments included median percentage reductions in seizure frequency per 28 days and seizure-freedom rates for patients receiving placebo and perampanel 4 mg/d (modal dose). Treatment-emergent adverse events (TEAEs) were assessed in patients receiving perampanel 4 mg/d at their TEAE onset. Outcomes were also assessed with/without enzyme-inducing antiseizure medications (EIASMs).

Results: The full analysis set included 979 patients with focal seizures (placebo: n = 616 [235 with FBTC seizures]; perampanel 4 mg/d: n = 363 [134 with FBTC seizures]). Compared with placebo, perampanel 4 mg/d conferred significantly greater median percentage reductions in seizure frequency per 28 days for focal (12.6% vs 21.1%; P = .0004) and FBTC seizures (17.4% vs 49.8%; P < .0001), and seizure-freedom rates for focal (0.8% vs 3.6%; P = .0018) and FBTC seizures (11.1% vs 18.7%; P = .0424). Seizure improvements with perampanel 4 mg/d were greater without EIASMs than with EIASMs. For assessment of TEAEs, overall 1376 patients with focal seizures received perampanel 4 mg/d at any time (FBTC seizures, n = 499). TEAEs with perampanel 4 mg/d occurred in 419 of 1376 (30.5%) and 148 of 499 (29.7%) patients with focal and FBTC seizures, respectively; most common was dizziness. The proportion of TEAEs was similar with or without EIASMs.

Significance: This post hoc analysis showed adjunctive perampanel 4 mg/d was efficacious and well tolerated in patients with focal seizures, with or without FBTC seizures. This dose may be a valuable treatment option in patients unable to tolerate higher perampanel doses up to 12 mg/d.