SPN-817 Open-Label Extension Study in Adults With Focal Onset Seizures

This is a Phase 2b open-label extension study to evaluate the long-term safety and efficacy of SPN-817.

Inclusion Criteria: 1. Completed antecedent SPN-817 double-blind study 2. Taking a stable dosage regimen (maintained during the antecedent study) of at least one antiseizure medication (ASM) and no more than 4 ASMs Exclusion Criteria: 1. Has current nonepileptic events that could be confused by the participant and/or study staff as epileptic seizures 2. Has any suicidal behavior or suicidal ideation related to Item 4 (active suicidal ideation with some intent to act without specific plan) or Item 5 (active suicidal ideation with specific plan and intent) based on the Columbia-Suicide Severity Rating Scale (C-SSRS) assessments in the antecedent study and at Visit 1 or more than one lifetime suicide attempt.