A Long-term Study of the Safety and Effectiveness of RAP-219 in Adults With Focal Onset Seizures

Inclusion Criteria: * Completion of the associated parent study (RAP-219-FOS-201) treatment period with acceptable tolerability, per Investigator. * Diagnosis of refractory focal epilepsy * Stable RNS(c) system settings * A demonstrated history of compliance with RNS(c) system data interrogation and upload * Good overall health other than focal epilepsy, per Investigator. * BMI ≥ 18 kg/m\^2 and ≤ 45 kg/m\^2 * Willing and able to adhere to all aspects of the protocol. Exclusion Criteria: * Known of hypersensitivity to RAP-219 * Any clinically unstable or serious medical, neurological (other than epilepsy), psychological, or behavioral problem; laboratory or ECG finding that would increase participant risk or should otherwise exclude the patient from participation, as assessed by Investigator * Pregnancy, lactation, or individuals of reproductive potential who do not agree to simultaneously use two effective birth-control methods