Overview

The purpose of this study is to learn about:

• To evaluate the efficacy of PRT-042 nasal spray for the Rapid Reduction of the depressive symptoms in adults with major depressive disorder (MDD) with acute suicidal ideation or behavior
• To evaluate the safety and pharmacokinetic (PK) characteristics after multiple dose of PRT-042 nasal spray in adults with major depressive disorder (MDD) with acute suicidal ideation or behavior

Eligibility

Inclusion Criteria:

1. Participant must meet Diagnostic and Statistical Manual of Mental Disorders (5th edition) (DSM-5) diagnostic criteria for Major Depressive Disorder (MDD), without psychotic features, based upon clinical assessment and confirmed by the Mini International Psychiatric Interview (MINI) .
2. Participants must have current suicidal ideation with intent, confirmed by a "Yes" response to Question B3 [Think (even momentarily) about harming or of hurting or of injuring yourself: with at least some intent or awareness that you might die as a result; or think about suicide (ie, about killing yourself)?] and Question B10 [Intend to act on thoughts of killing yourself?] obtained from the MINI.
3. Participant has a Montgomery Asberg Depression Rating Scale (MADRS) total score of greater than (≥) 28 and the score for item 10"suicide ideation" of greater than (≥) 3 predose on Day 1

Exclusion Criteria:

1. Participant has a current DSM-5 diagnosis of bipolar (or related disorders), antisocial personality disorder, or obsessive compulsive disorder.
2. Participant has a current clinical diagnosis of autism, dementia, or intellectual disability.
3. Participant has a current or prior DSM-5 diagnosis of a psychotic disorder, or MDD with psychotic features .
4. Participant meets the DSM-5 severity criteria for moderate or severe substance or alcohol use disorder, within the 6 months before screening
5. Participant has a current or prior diagnosis of a reatment resistant depression
6. Any nasal conditions or diseases that, in the investigator's judgment, may significantly affect the administration or absorption of a nasal product.
7. Participant has a history of malignancy within 5 years before screening
8. Pregnant or breastfeeding women, or those with a positive pregnancy test result during screening.
9. Previous participation in another clinical trial and receiving the investigational drug within 3 months prior to dosing.