Psychiatry · Medical Literature
Inhaled Mebufotenin (GH001) for Adult Patients With Postpartum Depression: A Phase 2a Open-Label Clinical Trial.
Abstract
Objective: Postpartum depression (PPD) is a debilitating mood disorder with peripartum onset. Current treatment options are limited in PPD. GH001 is a synthetic inhalation formulation of the psychoactive molecule mebufotenin (5-MeO-DMT). This trial investigated the preliminary efficacy and safety of GH001 in adult females with PPD. Methods: This phase 2a, proof-of-concept, open-label trial enrolled women aged 18-45 years (March 2023 to August 2024) with a Mini-International Neuropsychiatric Interview-confirmed diagnosis of major depressive disorder with peripartum onset. Patients had Montgomery-Asberg Depression Rating Scale (MADRS) scores of ≥28 at baseline. GH001 was administered as an individualized dosing regimen of up to 3 escalating doses (6, 12, and 18 mg) on day 1. The primary end point was the change in MADRS total score from baseline to day 8. Secondary end points included antidepressant response (≥50% reduction), remission (MADRS total score ≤10), and safety and tolerability of GH001. Results: Ten patients were enrolled. Mean baseline MADRS total score was 36.7 (SD = 4.8). Mean MADRS total score change from baseline to day 8 was -35.4 points (SD = 5.5; P < .0001). All patients achieved response and were in remission on day 8, which was first observed 2 hours after their final dose on day 1. Inhalation of GH001 was well tolerated, and no serious adverse events (AEs) were reported. All treatment-emergent AEs were mild or moderate, with headache as the most frequently reported AE. Conclusion: GH001 demonstrated rapid and significant improvements in depressive symptoms and remission of PPD with an acceptable safety profile and parallel improvements across secondary end points. Trial Registration: ClinicalTrials.gov identifier: NCT05804708; EudraCT identifier: 2021-006879-42.
Clinical relevance
In adult women aged 18–45 with moderate-to-severe postpartum depression (MADRS ≥28), does a single-day individualized inhaled dosing regimen of mebufotenin (GH001) produce clinically meaningful reductions in depressive symptom severity by day 8? __SNAPSHOT__ {"studyDesign":"Phase 2a, proof-of-concept, single-arm, open-label clinical trial","setting":"Single enrolling site in the United Kingdom (screened at 3 sites across the United Kingdom and the Netherlands); academic/clinical research setting","sampleSize":"n=10 (single arm; no comparator group)","population":"Adult women aged 18–45 years with a Mini-International Neuropsychiatric Interview (MINI)-confirmed diagnosis of major depressive disorder with peripartum onset and a baseline MADRS total score ≥28. Mean baseline MADRS was 36.7 (SD=4.8), reflecting moderate-to-severe illness. A subset of 4 patients were lactating.","intervention":"GH001 (synthetic inhaled mebufotenin/5-MeO-DMT) administered as an individualized dosing regimen (IDR) of up to 3 escalating doses (6 mg, 12 mg, and 18 mg) on a single day, with 1-hour intervals between doses, using the Volcano Medic 2 Vaporization System. A subsequent dose was administered only if the prior dose was well tolerated and had not produced a defined peak psychoactive experience (Peak Experience Scale mean score ≥75).","comparator":"Not applicable (single-arm, uncontrolled trial)","primaryOutcome":"Change in MADRS total score from baseline to day 8","followUp":"8 days (primary endpoint); breast milk pharmacokinetic sampling extended to day 8 for lactating patients","fundingSource":"Industry (GH Research PLC, Nasdaq: GHRS, a clinical-stage biopharmaceutical company that developed and manufactures GH001)"}
Key findings
Primary endpoint met: The mean MADRS total score decreased by −35.4 points (SD=5, as reported in the provided abstract) from baseline to day 8 (p<0.0001), corresponding to an approximate 96% reduction in mean symptom severity (calculated: −35.4 ÷ 36.7 = ~96.4%). All 10 patients (100%) achieved remission (MADRS ≤10) within 2 hours of dosing, and remission was sustained through day 8. Antidepressant response (≥50% MADRS reduction) was not separately quantified in the available sources but is implicit in the universal remission rate. Maternal functioning, assessed by the Barkin Index of Maternal Functioning (BIMF), improved by a mean of 34.1 points (56%) at day 8, with gains reported across 6 of 7 BIMF domains. No serious adverse events occurred; all treatment-emergent adverse events were mild or moderate in severity, with transient headache the most commonly reported. No treatment-emergent suicidal ideation or behavior was observed. In the lactating sub-group (n=4), mebufotenin levels in breast milk ranged from 0.24 to 3.11 ng/mL at 1 hour post-dose and declined to below the limit of quantification (~8 hours post-dose), with all measurements below the limit of quantification on days 2 and 8. NNT for remission cannot be calculated in the absence of a control arm. Confidence intervals for the primary endpoint were not reported in available sources.
Practice implications
This phase 2a trial demonstrates that a single-day inhaled mebufotenin regimen produced rapid and complete remission of moderate-to-severe postpartum depression in all 10 enrolled participants by day 8, with effects detectable as early as 2 hours post-dosing. The magnitude of MADRS reduction (~35 points from a mean baseline of ~37) is striking and exceeds thresholds typically considered clinically meaningful, but must be interpreted with extreme caution given the absence of a placebo arm, absence of blinding, and the very small sample size (n=10). The open-label design renders the contribution of expectation effects, spontaneous remission, and regression to the mean entirely unmeasurable. The 8-day follow-up window does not allow any inference about durability of response, relapse rates, or need for retreatment. Although the breast milk pharmacokinetic data are reassuring and suggest a brief pumping-and-discarding strategy (approximately 8 hours) may be feasible for lactating patients, the clinical implications for infant safety require formal evaluation. Mebufotenin is not approved by any regulatory authority for any indication. These results are best characterized as hypothesis-generating for a randomized, placebo-controlled, adequately powered trial. Only abstract-level and press release data were available for the breast milk SD value (abstract truncated at SD=5.); this is noted as a limitation of this summary. The finding of 100% remission across all 10 enrollees, while remarkable, should be weighted accordingly given the susceptibility to selection bias and the known psychoactive expectancy effects inherent to open-label psychedelic trials. __LIMITATIONS__ No control arm or blinding: placebo response, expectation effects, regression to the mean, and spontaneous remission cannot be disentangled from drug effect.,Extremely small sample size (n=10): severely limits statistical precision, generalizability, and power to detect adverse events; trial was not powered for inferential conclusions.,Very short follow-up (8 days): durability of remission, relapse rates, and need for repeat dosing are entirely unknown.,Industry sponsorship (GH Research PLC): high risk of publication and outcome reporting bias; the sponsor has substantial financial interest in the results.,Single enrolling site (UK only): limits geographic, ethnic, and healthcare-system generalizability.,Highly selected population: women aged 18–45 with MADRS ≥28 and MINI-confirmed diagnosis; findings may not apply to milder PPD, older or younger patients, or those with significant psychiatric comorbidities.,Open-label psychedelic trial: expectation of a profound psychoactive experience may amplify self-reported symptom improvement through non-specific mechanisms.,No long-term safety data: infant safety from breast milk exposure, maternal neurocognitive effects, and abuse potential are not characterized in this sample.,MADRS is a clinician-rated but subjective scale; without blinded raters, response ascertainment may be biased.,Abstract truncated in the provided text (SD for primary outcome not fully reported); this summary relies in part on press release data for quantitative details. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ In this phase 2a, open-label, single-arm trial of 10 women with moderate-to-severe postpartum depression, a single-day inhaled mebufotenin (GH001) regimen produced remission in all patients by day 8 (MADRS reduction −35.4 points, p<0.0001), with a favorable short-term tolerability profile and rapid breast milk clearance. These results are compelling as proof-of-concept but cannot support any change in practice: the absence of a placebo arm, blinding, and adequate sample size means the true drug-specific effect size remains unknown. Randomized, placebo-controlled, adequately powered trials with longer follow-up are required before any efficacy conclusions can be drawn.