Long-term open-label perampanel: Generalized tonic-clonic seizures in idiopathic generalized epilepsy

Assess the longer-term efficacy and safety of adjunctive perampanel (up to 12 mg/day) in patients aged ≥12 years with generalized tonic-clonic (GTC) seizures from the Open-label Extension (OLEx) Phase of Study 332 to determine whether responses obtained during the Core Study are maintained during long-term treatment.

Patients with GTC seizures previously enrolled in a randomized placebo-controlled trial of perampanel could enter an OLEx Phase comprising 6-week blinded conversion (during which patients previously randomized to placebo-switched to perampanel) and up to 136-week maintenance periods (maximum perampanel dose of 12 mg/day). A 4-week follow-up period was completed by all patients after the last on-treatment visit during the OLEx. We assessed seizure frequency outcomes from preperampanel baseline and the Core Study Pre-randomization Phase, retention rates, doses selected, and treatment-emergent adverse events (TEAEs).

Overall, 138 patients entered the OLEx. Median percent reductions in GTC seizures per 28 days from preperampanel were 77% (Weeks 1-13) and 90% (Weeks 40-52). Retention rates were 88% (6 months) and 75% (12 months). Seizure-freedom rates were maintained for at least 2 years regardless of prior treatment received during the Core Study. Most common modal daily dose was >4-8 mg/day (n = 93). Across the Core and OLEx Phases, 120 (87%) patients experienced TEAEs; the most common was dizziness.

Perampanel was generally well-tolerated, and the TEAEs reported here are consistent with the known safety profile of perampanel. Perampanel offers a long-term treatment option for patients (aged ≥12 years) with GTC seizures.