Age

18–70

Sex

ALL

Healthy volunteers

Not accepted

Have a diagnosis of moderate to severe major depressive disorder (MDD)
At Visit 1, currently taking a single SSRI, SNRI, or bupropion for at least 6 weeks with no dose modifications in the past 2 weeks by Visit 2
Willing to comply with all study assessments and procedures
Must not be pregnant or breastfeeding at time of enrollment or throughout study

Evidence of unstable medical condition
Nightly use of sleep medication
Diagnosed bipolar disorder, psychotic disorder, or dementia
Current moderate or severe substance use disorder
Has a history of hypersensitivity or allergic reaction to ALTO-300 or any of its components/excipients
Concurrent or recent participation in another clinical trial for mental illness involving an investigational product or device

Study of ALTO-300 in MDD