ALTO-100 in Bipolar Disorder With Depression (BD-D)

The purpose of this study is to assess antidepressant efficacy differences between ALTO-100 and placebo during the Double-Blind period in patients with bipolar disorder I or II with current major depressive episode, when used adjunctively to a mood stabilizer and/or atypical antipsychotic, related to patient characteristics. Additionally, safety, tolerability, and efficacy will be assessed in a subsequent open label treatment period.

Inclusion Criteria: * Have a diagnosis of BD-I or BD-II as well as BD-D * At baseline, taking a mood stabilizer, lithium (LI) or lamotrigine (LMG) or valproic acid (VPA, any form) or combination of Li + LMG or Li + VPA and/or taking an approved atypical antipsychotic medication (olanzapine, quetiapine, lurasidone, risperidone, ziprasidone, cariprazine, aripiprazole, lumateperone, asenapine, Iloperidone and Milsaperidone) for at least 6 weeks with no dose modifications in the past 2 weeks * Willing to comply with all study assessments and procedures * Must not be pregnant or breastfeeding at time of enrollment or throughout study Exclusion Criteria: * Evidence of unstable medical condition * Concurrent use of any prohibited medications or substance use disorder * Diagnosed psychotic disorder (other than mania or depression) * Current moderate or severe substance use disorder * Has a history of hypersensitivity or allergic reaction to ALTO-100 or any of its components/excipients * Concurrent or recent participation in another clinical trial for mental illness involving an investigational product or device