Perampanel reduces seizure frequency in patients with developmental and epileptic encephalopathy for a long term.

Seizures in patients with developmental and epileptic encephalopathies (DEEs) are often highly resistant to various antiseizure medications. Perampanel (PER) is a novel antiseizure medication that non-competitively inhibits the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor and is expected to reduce seizure frequency not only for focal seizures and generalized tonic-clonic seizures (GTCS) but also for other seizure types. This study aimed to clarify the long-term therapeutic efficacy and tolerability of PER in patients with DEEs. We analyzed data regarding patients' background characteristics, medication retention, trends in seizure frequency, and adverse events obtained from 24 patients with DEEs who had been on PER treatment for 60 months. The retention rates were 62.5% and 46.9% at 12 and 60 months, respectively. At 60 months after PER initiation, the rate of patients with > 50% seizure reduction was 33.3%, 33.3%, 38.5%, 54.5%, 54.5%, and 36.4% among patients with atypical absence seizures, tonic seizures, focal seizures, GTCS, myoclonic seizures, and atonic seizures, respectively. The frequency of adverse events was 70.8%. PER showed long-term efficacy in various seizure types. PER is a promising treatment option for patients with DEEs.