In This article

• GH001 is an investigational treatment: It is an inhaled synthetic formulation of mebufotenin (5-MeO-DMT), a potent psychedelic compound being studied for its potential antidepressant effects.
• Rapid improvement: In a phase 2a open-label trial of 10 women with moderate-to-severe postpartum depression, depressive symptoms decreased substantially, with improvement observed as early as two hours after dosing.
• All 10 participants met criteria for response and remission by day 8
• Short-term tolerability was generally favorable: No serious adverse events were reported. 
• Larger randomized controlled trials with longer follow-up are needed to establish efficacy, durability, safety, and the potential role of GH001 in treating postpartum depression.

Over the past several years, novel, rapidly acting antidepressants have expanded treatment options for women with postpartum depression (PPD), including brexanolone and zuranolone. More recently, researchers have begun exploring psychedelic compounds as potential treatments for a range of psychiatric disorders, including postpartum depression.

A recent phase 2a clinical trial published in The Journal of Clinical Psychiatry investigated GH001, an inhaled synthetic formulation of mebufotenin (5-methoxy-N,N-dimethyltryptamine, or 5-MeO-DMT), in adults with moderate-to-severe PPD. The findings suggest that GH001 may have a rapid antidepressant effect, with substantial reductions in depressive symptoms observed within hours of administration. However, these results are preliminary and require confirmation in larger, controlled studies.

What Is GH001?

GH001 is an investigational, inhaled formulation of mebufotenin (5-MeO-DMT), a potent psychedelic compound that occurs naturally in certain plants and in the venom of the Colorado River toad. The synthetic formulation is designed for administration by inhalation in a supervised clinical setting.

Mebufotenin acts as a nonselective serotonin receptor agonist, with greater affinity for the 5-HT1A receptor subtype than for the 5-HT2A receptor subtype. It has a short plasma half-life, and its acute psychoactive effects are relatively brief, generally lasting approximately 20-25 minutes per dose.

These effects include intense alterations in consciousness and perception. Because the experience can be psychologically and physiologically intense, administration requires careful supervision and monitoring.

Earlier clinical studies of GH001 in patients with treatment-resistant depression have reported rapid antidepressant effects and an acceptable safety profile. The phase 2a trial described here is the first investigation of the use of GH001 in postpartum depression.

Study Design

This phase 2a, proof-of-concept, open-label trial was conducted in the United Kingdom and the Netherlands. The study enrolled 10 women aged 18-45 years with a diagnosis of major depressive disorder with peripartum onset, confirmed using the Mini-International Neuropsychiatric Interview.

Participants were more than four weeks postpartum at the time of dosing and within 12 months postpartum at screening. All had moderate-to-severe depressive symptoms, with baseline scores of at least 28 on the Montgomery-Åsberg Depression Rating Scale (MADRS).

GH001 was administered under medical supervision using an individualized dosing regimen:

• Participants initially received an inhaled dose of 6 mg.
• If the participant had not experienced an intense psychoactive effect and the preceding dose was considered safe and well tolerated, additional doses of 12 mg and then 18 mg could be administered.
• Up to three doses were given on a single day, with approximately one hour between doses.

The study did not include a planned psychotherapeutic intervention before, during, or after dosing, although administration took place under clinical supervision.

Changes in depressive symptom severity were measured using the MADRS total score at baseline to day 8. Antidepressant response was defined as a reduction of at least 50% in MADRS score; remission was defined as a MADRS score of 10 or lower.

Results

Ten participants were enrolled. The mean baseline MADRS score was 36.7 (SD = 4.8), indicating substantial depressive symptom severity. The investigators reported the following findings:

• Rapid reduction in depressive symptoms: The mean MADRS score decreased by 35.4 points from baseline to day 8 (P < .0001), corresponding to an approximately 96% reduction in the severity of depressive symptoms.
• Improvement within hours: Significant reductions in MADRS scores were observed as early as two hours after dosing and were maintained at the day 2 assessment.
• Response and remission in all participants: All 10 participants met criteria for both response and remission by day 8. Remission was first observed two hours after the final dose on day 1 and was maintained through day 8.
• Generally favorable short-term tolerability: No serious adverse events were reported. Treatment-emergent adverse events were mild or moderate, with headache the most frequently reported event.
• Brief psychoactive effects: The acute psychoactive experience generally lasted approximately 22–25 minutes per dose. Transient increases in blood pressure and heart rate were also observed and resolved spontaneously. All participants were considered ready for discharge on the day of dosing.

What Are the Clinical Implications?

The results of this small, early-phase trial are notable because of the magnitude and speed of the reported antidepressant response. All 10 participants achieved remission, with improvement apparent within two hours of dosing and maintained over the eight-day observation period.

The potential for a rapidly acting treatment is particularly relevant in postpartum depression, which can have substantial consequences for maternal functioning and the developing mother–infant relationship. However, several important limitations should be considered when interpreting these findings.

• The sample was very small. With only 10 participants, the study cannot provide a reliable estimate of the treatment’s efficacy or identify less common adverse effects.
• The study was open-label and had no control group. Without a placebo or active comparator, it is not possible to determine how much of the observed improvement was attributable specifically to GH001.
• Follow-up was brief. Outcomes were assessed through day 8, so the study does not establish whether remission persists over subsequent weeks or months, or whether repeat treatment might be needed.
• The treatment requires supervised administration. Although the acute psychoactive effects were brief, the intensity of the experience and the observed cardiovascular changes highlight the importance of appropriate clinical monitoring.
• Further safety data are needed. Larger studies will be required to characterize adverse effects and establish safety in the postpartum population. 
• Preliminary data on breastfeeding: Metabolites of GH001 were not detected in breast milk at 10 hours after dosing.  Additional research is also needed to clarify use during lactation and any implications for breastfeeding.

What’s Next?

GH001 represents an early-stage investigational approach to postpartum depression that may offer a very rapid reduction in depressive symptoms. The findings are encouraging, but they do not yet establish its efficacy, durability, or safety in routine clinical practice.

Future studies should include larger samples, randomized controlled designs, and longer follow-up to determine whether the initial improvement is sustained and to better characterize the treatment’s risks and benefits. Research will also need to clarify which individuals are most likely to benefit and how this approach might fit into existing treatment strategies for postpartum depression.

The speed of response reported in this trial is striking.  While we do not have any head-to-head comparisons, the current study suggests that the time to response is considerably faster than what has been reported for zuranolone and brexanolone. 

For now, these findings provide preliminary evidence that psychedelic compounds may warrant further investigation as potential treatments for postpartum depression.

—Ruta Nonacs, MD PhD