Safety and Efficacy of Perampanel as Adjunctive Therapy in Patients with Refractory Focal Epilepsy Over 12 Months: Clinical Experience in a Real-World Setting

Abstract Background The main purpose of this study is to assess efficacy and tolerability of perampanel (PER), a noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor antagonist, as an add-on treatment in adult patients with refractory focal-onset seizures. Patients and Methods A prospective, open label, observational study was conducted in patients with refractory focal-onset seizures treated with PER at our Epilepsy Unit, from May 2015 to February 2016. Patients were followed up for 1 year. Frequency of seizure and tolerability was assessed every 3 months. Patients were under a polytherapy, and the mean number of concomitant antiepileptic drugs (AEDs) at PER initiation was 2.9. Results We consecutively enrolled 52 patients (M/F = 18/34). Three were lost on follow-up. Mean age was 38.7 years, with a mean duration of disease of 28.1 years. After 1 year of treatment, 57.14% reported a 50% or greater reduction in seizure frequency; five (10.21%) were seizure free. Six (12.25%) patients reported a reduction lower than 50%. Mean dosage of PER was 7.57 mg. Thirty-one patients were taking enzyme-inducing AEDs (carbamazepine, oxcarbazepine, phenytoin). In this subgroup, the responder rate was 45.2%. Twenty-one patients reported side-effects, most frequently somnolence (11), vertigo/ataxia (6), and aggressiveness (5). Eleven (22.4%) patients reduced or discontinued at least one concomitant AED, while the electroencephalography improved in four (8.16%). Sixteen (32.65%) patients withdrew PER, after a mean duration of 163 days, the mean dosage being 6.4 mg (range 4–12). Conclusions Adjunctive PER can achieve clinically meaningful improvement, or even seizure freedom, in almost two-thirds of patients suffering from refractory focal-onset epilepsies. It seems similarly safe and well-tolerated. Enzyme-inducing AEDs may limit the efficacy of PER.