Recruitment of this patient population was more challenging than anticipated. The sponsor concluded that a sufficient amount of patients have completed the trial to demonstrate proof of concept in this patient population.

This study is a multicenter, open-label, single-arm Phase 2 clinical trial. Approximately 15 female participants with clinically diagnosed postpartum depression (PPD) will be included in this study. The participants will receive an individualized dosing regimen (IDR) with at least one and up to three doses of GH001 administered within a single day.

Inclusion Criteria:

• Is female and in the age range between 18 and 45 years (inclusive) at screening.
• Has a body mass index (BMI) in the range of 18.5 and 35 kg/m2 (inclusive) at screening.
• Meets the trial criteria for PPD as assessed by a trial psychiatrist or registered clinical psychologist.

Exclusion Criteria:

• Has one or more first or second degree relatives with a current or prior diagnosis of bipolar disorder, psychotic disorder or other mood disorder (including MDD) with psychotic features.
• Current pregnancy resulting in termination, still-birth, pre-term delivery (before week complete gestational week 37), need for intensive care therapy of mother or child, or adoption of child away from patient.
• Has taken prohibited medication or prohibited dietary supplements within the specified timeframe prior to dosing.
• Has previously experienced a significant adverse reaction to a hallucinogenic or psychedelic drug according to the investigator's judgment.
• Has a clinically significant abnormality in physical examination, vital signs, ECG, or clinical laboratory parameters which renders the patient unsuitable for the trial according to the investigator's judgment.
• Patient who has a positive pregnancy test at screening or on the pretest day, is pregnant, or plans to become pregnant during the course of the trial and up to 90 days after GH001 dosing.