This study is examining a new drug, RAP-219, for adults aged 18-75 with focal seizures. Focal seizures are a type of seizure that affects only one part of the brain. The study aims to see if RAP-219 is safe and helps reduce these seizures. Participants will be placed in one of three groups: high dosage, medium dosage, or placebo (no active drug), with about 333 people involved. After the main test period, participants can choose to continue in a longer safety study or have an 8-week follow-up.

Eligibility: To join, you must have had focal epilepsy for at least 2 years, a Body Mass Index (BMI) between 18-45, and be on 1 to 3 seizure medications. You should also be able to record your seizures daily using an electronic diary. You cannot join if you have certain other medical conditions or have had epilepsy surgery recently.

• The study involves multiple visits and medication testing.
• Participants may continue with a long-term safety study after the initial phase.
• Ensure no recent participation in another drug study before joining.