This clinical trial is focused on studying migraine headaches, which are severe headaches that can occur with or without warning signs known as aura. The study is testing a treatment called Rimegepant, also known by its code name BHV-3000. Rimegepant is taken as an oral lyophilisate, which means it dissolves in the mouth. The purpose of the study is to evaluate how well Rimegepant works and how tolerable it is for preventing migraines in adults who have not had success with other oral preventive medications.

Participants in the study will be randomly assigned to receive either Rimegepant or a placebo, which looks like the medication but does not contain the active ingredient. The study is designed to be double-blind, meaning neither the participants nor the researchers will know who is receiving the actual medication or the placebo. This helps ensure that the results are not biased. The study will last for several weeks, during which participants will take the medication every other day and report the number of migraine days they experience each month.

The main goal is to see if there is a reduction in the number of migraine days per month compared to before the study started. Additionally, the study will look at whether participants experience fewer days with moderate or severe headache pain and any changes in their ability to perform daily activities. The results will help determine if Rimegepant is an effective option for people who have not found relief with other migraine prevention treatments.