This clinical trial is focused on studying the prevention of migraine, a condition characterized by severe headaches that can be accompanied by symptoms like nausea and sensitivity to light. The study includes participants who experience either chronic migraine or episodic migraine. Chronic migraine involves headaches on 15 or more days per month, while episodic migraine occurs less frequently. The treatment being tested is a medication called Atogepant, which is taken orally in the form of a tablet.

The purpose of this study is to evaluate the long-term safety and tolerability of Atogepant when used over a period of 156 weeks. Participants will take a 60 mg dose of Atogepant once daily. The study is designed to observe how well participants tolerate the medication over this extended period and to monitor any side effects that may arise. This is an open-label study, meaning that both the researchers and participants know which treatment is being administered.

Throughout the study, participants will be regularly monitored for any adverse events, which are any unwanted effects that occur during the trial. The study will also assess any significant changes in laboratory test results, heart function as measured by electrocardiograms (ECGs), and vital signs such as blood pressure and heart rate. The goal is to ensure that Atogepant is safe for long-term use in preventing migraines in those who suffer from this condition.