This study is to see if a medicine called azetukalner can help adults with bipolar depression feel better. Bipolar depression is when someone with bipolar disorder, which can cause extreme mood changes, feels very sad or down. In this study, some people will get azetukalner, and others will get a placebo, which is a fake treatment that doesn't have any medicine. This helps researchers understand if azetukalner really works.

• You must be between 18 and 74 years old and have had your first serious depressive episode before age 50.
• You're not eligible if you have other major depressive disorders or psychiatric conditions or if you've had substance abuse issues recently.
• The study involves multiple visits and you should not have used certain medications recently.

Participating in this study means you'll help scientists learn more about treating bipolar depression, but you need to make sure you meet all the criteria and are comfortable with the requirements. If you are pregnant or planning to be, you cannot join.