One Nasal Dose, Two Hours in Clinic: What the New JAMA Mebufotenin Trial Means for Canadian Practitioners

For most of the past decade, the practical objection to psychedelic-assisted therapy has been time. A psilocybin session can occupy a treatment room and two staff for six to eight hours. A new trial published on October 26, 2026 in JAMA tests a very different model: a single intranasal dose of mebufotenin, a synthetic form of 5-MeO-DMT, with most participants meeting discharge criteria within about two hours.

The study is the first full peer-reviewed report of a phase 2b trial run by AtaiBeckley (formerly Beckley Psytech) at 38 sites in Australia, Europe and the United States between September 2023 and April 2025. The company announced headline results in July 2025, but the JAMA paper, led by Dr. David Feifel of the Kadima Neuropsychiatry Institute in California, gives practitioners the full data for the first time, alongside a measured independent editorial by Dr. Chittaranjan Andrade of India's National Institute of Mental Health and Neurosciences.

Medically reviewed by Jacque Lovely, RN, MN, MBA, PMP, Reg #74334.

What the trial did

Researchers enrolled 193 adults aged 18 to 75 with moderate-to-severe major depressive disorder that had not responded to two to five antidepressant trials in the current episode. Existing antidepressants were washed out where necessary. Participants were randomized to a single intranasal dose of 8 mg or 12 mg of mebufotenin benzoate, or to a 0.3 mg sub-perceptual dose that served as the comparator. Everyone received psychological support around the dosing session, and the blinded follow-up ran for eight weeks. People who reported suicidality were excluded.

The primary outcome was the change in the Montgomery-Åsberg Depression Rating Scale (MADRS) at day 29 for the 12 mg dose versus the comparator.

What it found

At day 29, the 12 mg group improved by 11.1 points on the MADRS compared with 5.5 points for the comparator, a difference of 5.3 points (95% CI, −8.9 to −1.8; P = .003). The 8 mg group improved by 12.5 points, a difference of 6.2 points versus comparator. Both active doses separated from the comparator at every time point from day 2 through day 57, which suggests the effect appeared within about two days and held for the eight-week blinded period.

Response rates at day 29 were 35% for 8 mg, 34% for 12 mg and 12% for the comparator; remission rates were 26%, 18% and 8%. Treatment-emergent adverse events were common in all arms, including the comparator (76%, 85% and 73%), but 99.7% were mild or moderate; headache, nausea and nasal discomfort were typical and generally resolved on dosing day. ScienceAlert's coverage notes that one participant experienced two severe panic attacks. Discharge readiness was assessed from 90 minutes after dosing, and 85% of the 8 mg group and 78% of the 12 mg group were judged ready within two hours.

The authors conclude that single doses were well tolerated and produced rapid, robust and durable reductions in depressive symptoms, and they argue that the shorter monitoring period and fewer clinic visits could make this approach more accessible than psilocybin or esketamine. According to ScienceAlert, the 8 mg dose has been selected for phase 3 because it offered the best balance of efficacy and tolerability.

The editorial's caution

Dr. Andrade's accompanying editorial is the part practitioners should read most closely. He writes that "the antidepressant effect was incomplete," noting that the average participant improved by roughly 30%, and that response and remission rates were below those typically seen with ketamine and electroconvulsive therapy. He also argues that the trial's definition of treatment resistance, failure of as few as two antidepressants, was lenient, and that "difficult-to-treat" is a more accurate label. Most importantly for clinical planning, he points out that "patients with difficult-to-treat depression require long-term maintenance treatment," and that because the drug was tested on its own after washout, the study cannot say how or when to transition patients to ongoing care.

A one-in-three response rate is a meaningful signal in a hard-to-treat population, but it is not a cure, and the study does not say what happens after week eight. A company-reported open-label extension from November 2025 gave a second dose at eight weeks, but those data are uncontrolled and are not part of the JAMA paper.

Why this matters in Canada

Three things make this trial worth a Canadian practitioner's attention even though mebufotenin is investigational and not approved by any regulator.

First, the commercial trajectory is now clear. On July 16, 2026, Eli Lilly announced it would acquire AtaiBeckley for about US$2.8 billion, with BPL-003 as the lead asset, FDA Breakthrough Therapy designation in hand and phase 3 activities under way. If the program succeeds, Health Canada will eventually be asked to review a dossier built on this data.

Second, the delivery model is different. Most Canadian clinical experience to date, including requests under Health Canada's case-by-case authorization initiated by a physician, has centred on psilocybin and MDMA and the long sessions they require. A roughly two-hour in-clinic visit changes staffing, scheduling and economics, but it does not remove the need for screening, psychological support and a plan for what follows; the trial included psychological support in every arm.

Third, the safety profile deserves sober reading. Adverse events were common even on the sub-perceptual dose, and the exclusion of participants reporting suicidality means the results apply to a narrower population than many clinics see.

What practitioners can do now

The practical takeaway is not to prepare for mebufotenin specifically, but to recognize that the field is diversifying faster than any single protocol. The core skills remain the same: careful screening, informed consent that is honest about partial response, support during altered states of varying length, and integration and maintenance planning after the session ends. Those competencies transfer across compounds.

ATMA CENA's Advanced Pathways, which include the Psychedelic Therapy Foundations course as part one, are built around exactly those transferable skills. If you are a nurse, physician, psychologist or therapist thinking about where this field is heading, you can explore the programs at the psychedelic therapy training page or book a conversation with a program advisor.

Sources

1. Single Intranasal Administration of the Psychedelic Mebufotenin for Treatment-Resistant Depression: A Randomized Clinical Trial. JAMA, 2026.
2. Single Intranasal Administration of the Psychedelic Mebufotenin for Treatment-Resistant Depression: Research Summary. JAMA, 2026.
3. Scientists Tested a Toad Venom Psychedelic on Treatment-Resistant Depression. Here's What Happened.. ScienceAlert (syndicated), 2026.
4. Lilly to acquire AtaiBeckley to advance therapies for treatment-resistant depression and other mental health conditions. Eli Lilly and Company (PR Newswire), 2026.
5. BPL-003: Positive Phase 2b Open-Label Extension Study Data. Psychiatric Times, 2025.
6. Phase 2b trial of Beckley's BPL-003 intranasal mebufotenin meets its primary endpoint. OINDP News, 2025.