**Study Summary** This study is testing a new drug called **K-645** to help treat **migraine** attacks, which are intense headaches often accompanied by nausea and sensitivity to light. People aged 18 to 65 who have been experiencing migraines for over a year can join. The study is designed to be **randomized** (participants are randomly assigned to groups), **double-blind** (neither participants nor researchers know who is getting the actual drug or a **placebo**, which is a fake treatment), and **placebo-controlled** (compared against a placebo). Participants will test two different doses of K-645 in a three-period crossover, meaning they will switch between the drug and placebo at different times. The study examines how well the drug works, how safe it is, and its side effects. **Key Points:** - **Duration & Visits:** The study involves multiple visits over different periods. - **Participation:** Must use personal smartphone for study diary apps. - **Compensation:** Details on compensation not provided in the summary, but participation is voluntary and requires informed consent. **Note:** Pregnant women or those planning to become pregnant cannot join. Participants must agree to specific contraception methods if applicable.