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

Who May Qualify: - 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. Who Should NOT Join This Trial: - 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 Always talk to your doctor about whether this trial is right for you.