The purpose of the study is to evaluate the efficacy, safety and tolerability of the 3 selected dose regimens of padsevonil (PSL) administered concomitantly with up to 3 anti-epileptic drugs (AEDs) compared with placebo for treatment of observable focal-onset seizures in subjects with drug-resistant epilepsy.
• Diagnosis of focal epilepsy per 1989 International League Against Epilepsy (ILAE) criteria at least 3 years before study entry
• Subject has failed to achieve seizure control with >=4 tolerated and appropriately chosen prior antiepileptic drugs (AED), including past and ongoing treatment, that were individually optimized for adequate dose and duration. Prior discontinued AED treatment would need to be assessed by the Investigator considering the patient medical records and patient and/or caregiver interview. ‘Prior AED’ is defined as all past and ongoing AED treatments with a start date before the Screening Visit (Visit 1)
• Average of >= 4 spontaneous and observable focal seizures (type IA1 (i.e. focal aware), IB (i.e. focal impaired awareness), IC (i.e. focal to bilateral tonic-clonic)) per month
• Current treatment with an individually optimized and stable dose of at least 1 and up to 3 AEDs for the 8 weeks prior to the Screening Visit with or without additional Vagus Nerve Stimulation (VNS) or other neurostimulation treatments