Perampanel for the treatment of patients with myoclonic seizures in clinical practice: Evidence from the PERMIT study

Purpose: To investigate the effectiveness, safety and tolerability of perampanel (PER) in treating myoclonic seizures in clinical practice, using data from the PERaMpanel pooled analysIs of effecTiveness and tolerability (PERMIT) study. Methods: PERMIT was a pooled analysis of 44 real-world studies from 17 countries, in which patients with focal and generalised epilepsy were treated with PER. This post-hoc analysis included patients with myoclonic seizures at baseline. Retention and effectiveness were assessed after 3, 6, and 12 months; effectiveness was additionally assessed at the last visit (last observation carried forward). Effectiveness assessments included responder rate (≥50% seizure frequency reduction from baseline) and seizure freedom rate (no seizures since at least the prior visit). Safety and tolerability were assessed by evaluating adverse events (AEs) and discontinuation due to AEs. Results: 156 patients had myoclonic seizures (59.0% female; mean age, 32.1 years; idiopathic generalised epilepsy, 89.1%; Juvenile Myoclonic Epilepsy, 63.1%; monthly median myoclonic seizure frequency [interquartile range], 1.7 [1.0-10.0]; mean [standard deviation] prior antiseizure medications, 2.9 [2.6]). Retention was assessed for 133 patients (mean time, 12.1 months), effectiveness for 142, and safety/tolerability for 156. Responder and seizure freedom rates were, respectively, 89.5% and 68.8% at 12 months, and 85.9% and 63.4% at the last visit. Incidence of AEs was 46.8%, the most frequent being dizziness/vertigo (19.2%), irritability (18.6%) and somnolence (9.6%). AEs led to discontinuation of 14.0% of patients over 12 months. Conclusion: PER was associated with reduction in myoclonic seizure frequency in patients with myoclonic seizures treated in everyday clinical practice.