Astroscape: A Study of Radiprodil on Safety, Tolerability, Pharmacokinetics, and Effect on Seizures and Behavioral Symptoms in Patients With TSC or FCD Type II

Approximately 20 participants with TSC and 10 participants with FCD type II will be enrolled. The effects of radiprodil are assessed in participants with treatment-resistant seizures (with or without behavioral symptoms). The daily doses of radiprodil will be individually titrated for every participant and all the participants will receive study drug. This study is divided into the following periods: PART A: * Screening/Observation Period (up to six(6) weeks): Investigators assess eligibility followed by an Observation Period (at least four(4) weeks) to evaluate seizure frequency. * Titration Period (approx. four(4) weeks): Radiprodil twice daily will be administered in escalating doses and plasma concentrations, safety, and tolerability assessed. Once a safe and potentially effective dose has been established, the participant will immediately enter the Maintenance Period. * Maintenance Period (approx. twelve(12) weeks): The participant will continue to take the safe and potentially effective dose identified during the Titration Period. At the end of the Maintenance Period the participant will either be invited to enter Part B or the Tapering and Safety Follow-up Period. * Tapering (15 days) and Safety Follow-up Period (14 days): a participant who doesn't take part in the long-term treatment period (Part B) will taper (ie gradually decrease) the study medicine for 15 days and enter a safety Follow-up Period (14 days). In this case, the participant will have one (1) last visit at the end of the safety Follow-up Period. PART B: * Long-Term Treatment Period (not specified): During the Long-Term Treatment Period (Part B), participants will continue taking radiprodil at the usual dose level and making regular visits to the study site. * Tapering (15 days) and Safety Follow-up Period (14 days): at the end of the long-term treatment period (Part B), the participant will taper (ie gradually decrease) the study medicine for 15 days and enter a safety Follow-up Period (14 days) after his/her last dose of radiprodil. The participant will have one (1) last visit at the end of the safety Follow-up Period.