Zuranolone is a medicine being studied for its effects on young people aged 12-17 with Major Depressive Disorder (MDD), which is a condition causing intense sadness and lack of interest in activities. The study aims to understand how the body processes the medicine (this is called pharmacokinetics) and to ensure it's safe to use.

To join the study, participants must have a certain level of depression measured by a test called the Children's Depression Rating Scale-Revised (CDRS-R). They should also weigh more than 20 kg and must have started puberty. Some conditions like psychosis, bipolar disorder, or autism can prevent someone from joining. It's important that the participant's parent or caregiver can attend all visits and help with the study's requirements.

• The study involves regular visits to the study site.
• Participants cannot have a recent history of drug or alcohol misuse.
• Safety is a key concern, so participants with certain health risks may be excluded.