Published on 17 September 2026
Buprenorphine After Ketamine: Can It Extend the Antisuicidal Effect?
The Essentials
Ketamine rapidly cuts suicidal ideation, but its effect fades quickly. A randomized, double-blind trial tested a simple idea: sustain that benefit with very low-dose sublingual buprenorphine, given for four weeks starting at hour 48. Among 45 evaluable patients, the drop in suicidal ideation scores was nearly twice as large under buprenorphine as under placebo, with a moderate-to-large effect size. Depression scores, by contrast, did not differ significantly between the groups, and no serious treatment-related adverse events occurred. This is the first trial to show that a pharmacological intervention can sustain and enhance ketamine’s antisuicidal effect. One center, 45 patients, no replication yet: a proof of concept, not a practice change.
Context
Acute suicidal ideation is an emergency that classical pharmacology reaches too late. Antidepressants take weeks to act, while the crisis plays out in days. Ketamine shifted that timeline, but introduced another problem: its effect is sharp and transient, forcing repeated administrations in a demanding clinical setting.
Hence the question this trial asks, mechanistic before it is therapeutic: through which pathway does ketamine act on suicidality, and can that pathway be sustained by something other than ketamine itself?
Mechanism
Why buprenorphine, and not something else
Ketamine is an NMDA receptor antagonist, but preclinical and clinical work suggests its antidepressant and antisuicidal effects are partly mediated by the mu-opioid receptor. A foundational study, led in part by the same group, showed that blocking opioid receptors with naltrexone abolished ketamine’s antidepressant effect. If this pathway matters, a partial mu-receptor agonist should be able to take over.
The table below summarizes buprenorphine’s pharmacology. Worth noting: the trial measured no mechanistic marker, neither receptor occupancy nor an opioid-antagonist arm. The opioid hypothesis is therefore not demonstrated here, only made more plausible by a clinical result.
| Target | Buprenorphine’s action | Presumed role in suicidality |
|---|---|---|
| Mu receptor (MOR) | Partial agonist | Pathway tested by the trial: presumed to prolong the antisuicidal signal initiated by ketamine |
| Kappa receptor (KOR) | Antagonist | Pharmacological background, outside the trial’s scope: the kappa system is linked to dysphoria, and blocking it could contribute to the effect |
| NMDA receptor | Ketamine’s target | Triggers the initial effect, partly relayed through the opioid pathway according to the hypothesis under test |
The Trial at a Glance
| Question (PICO) | |
|---|---|
| Population | |
| Adults with major depressive disorder and a total score of at least 6 on the Scale for Suicide Ideation. 50 patients received the ketamine infusion, 68% female, 45 evaluable. Enrollment from November 2020 to March 2025 | |
| Intervention | |
| Sublingual buprenorphine, 0.2 to 0.8 mg/day for 4 weeks, starting 48 hours after a single open-label ketamine infusion (0.5 mg/kg over 40 minutes) | |
| Comparator | |
| Matched sublingual placebo, identical protocol | |
| Primary outcome | |
| Change in total SSI score, assessed weekly from day 1 through day 31 | |
| Design | |
| Randomized 1:1, double-blind, placebo-controlled trial, single outpatient center in the United States, Stanford-affiliated team based on the listed affiliations · CEBM 1b · RoB 2 bias tool |
Quality Control
| Criterion | Status |
|---|---|
| Randomization and blinding | Robust |
| Finding1:1 allocation, double-blind, matched placebo | |
| Primary outcome | Robust |
| FindingPrespecified SSI, weekly measurements, mixed-effects modeling | |
| Trial registration | Caveat |
| FindingEthics approval documented, but no identifiable trial registration number in the sources consulted | |
| Sample size | Caveat |
| Finding45 evaluable patients, 23 versus 22: very small, and no power calculation reported | |
| Replication | Caveat |
| FindingFirst trial of its kind, no replication to date | |
| Funding and conflicts of interest | Caveat |
| FindingPublicly funded (NIH, grant K08 DA055157), but several authors declare extensive industry ties, including equity in companies in the field | |
Results
| Outcome | Result |
|---|---|
| Suicidal ideation, effect size | Glass delta = 0.76 (95% CI: 0.11 to 1.39) |
| PEB readingModerate-to-large effect wide interval, the lower bound skirts no effect at all | |
| Trajectory over time | Significant time-by-treatment interaction (p < 0.001) |
| PEB readingThe two curves diverge clearly | |
| Improvement in each arm | Both groups improved significantly, more so under buprenorphine |
| PEB readingPart of the benefit is attributable to ketamine alone | |
| Overall depression | No significant difference between groups |
| PEB readingSecondary endpoint, no stated power calculation | |
| Safety | No serious treatment-related adverse events |
| PEB readingReassuring but 45 patients over 4 weeks cannot settle the tolerability of an opioid | |
Two other figures circulate as well, a response rate of 78% versus 48% and a number needed to treat of 3. They come from the full text, not the published abstract, and they do not reconcile with the available sample sizes: an absolute difference of 30 points gives a number needed to treat of 4, and 48% does not correspond to any whole number out of 22 patients. PEB does not carry these figures over until they have been checked against the complete article.
The most puzzling finding is not the headline number, it is what does not move. Mood does not improve more than under placebo, while suicidal ideation does recede. This gap echoes an old clinical intuition, a patient can stop wanting to die before feeling better, but it rests here on a nonsignificant secondary endpoint in a small sample. Read it as a lead, not a demonstration.
Critical Appraisal
| RoB 2 domain | Judgment |
|---|---|
| D1, randomization | Caveat |
| FindingSingle center: possible imbalance on unmeasured factors, limited external validity | |
| D2, deviations from intended interventions | Caveat |
| FindingOral burning in 17.4% of patients under buprenorphine versus none under placebo: blinding may have been partly compromised | |
| D3, missing outcome data | Caveat |
| FindingThe 45 analyzed patients correspond to the 23 and 22 in the two arms. The 5 patients who received ketamine but were not evaluable are therefore absent from the primary analysis, which is not an intention-to-treat analysis | |
| D4, measurement of the outcome | Robust |
| FindingPrespecified SSI, repeated measures | |
| D5, selection of the reported result | Caveat |
| FindingThe lack of difference on depression is understated as a limitation | |
Two points deserve to be stated clearly, because they circulate backwards. The population is not treatment-resistant depression: the published criteria are a major depressive episode and an SSI score of at least 6, resistance does not appear among them. And public funding does not excuse skipping the conflict-of-interest statement, which is extensive for several authors.
Level of Evidence
PEB’s assessment: moderate confidence in the direction of the effect, low confidence in its magnitude. The trial is clean and well conducted. What lowers confidence is scale: 45 patients, a single center, no replication, a confidence interval whose lower bound skirts zero.
The Colleague Test
What an experienced colleague might say if handed this study for two minutes, between two consultations.
“A promising proof of concept, not generalizable as it stands. The effect size is impressive and the reasoning holds together, but 45 patients in one center, and nothing that proves the mechanism: I want to see a multicenter replication before drawing any conclusions.”
Translated for practice: keep the hypothesis, not the course of action. The day a multicenter trial confirms the trajectory, this study will be cited as the one that opened the way.
What you can use starting Monday morning. The prescription does not change, but three things become usable right away.
- Explain to a patient referred to a ketamine clinic why the effect is fast and why the follow-up needs to be planned, rather than letting them discover the drop-off on their own.
- Answer precisely when a patient or family member has read a press headline about this study, by separating what is shown from what is hoped for.
- Anchor a clinical distinction that reaches well beyond this molecule: treating suicidality and treating depression are not the same goal, and are not measured with the same scales.
One open question the trial does not settle: in a patient already on buprenorphine for another indication, how should the response to ketamine be interpreted? The 2018 foundational study showed that blocking opioid receptors abolishes ketamine’s antidepressant effect, which is enough to make this a point of vigilance, not a recommendation.
Frequently Asked Questions
Can buprenorphine be prescribed for suicidal ideation today?
No. The use is off-label for this indication and rests on a single small trial. This is not a practice recommendation.
Is this strategy usable in outpatient private practice?
Not as it stands, since the protocol begins with a ketamine infusion, unavailable outside a specialized setting. The underlying reasoning, however, applies everywhere.
Why does suicidal ideation improve without depression changing?
This is the question the study raises without resolving it. Suicidality and mood may rest on partly distinct circuits, but this finding concerns a nonsignificant secondary endpoint in a sample of 45 patients, with no power calculation. An absence of significant difference is not proof of an absence of effect.
Were the patients treatment-resistant?
No. The published inclusion criteria are a major depressive episode and a score of at least 6 on the Scale for Suicide Ideation. Treatment resistance is not among them, contrary to what has sometimes been reported.
Should this be called a breakthrough?
No, and framing it that way would do the topic a disservice. It is an elegant proof of concept, in an area where usable tools are still scarce.
Annotated Bibliography
Tucciarone JM, Bandeira ID, Blasey C, Kratter IH, Ehrie J, Keller J, et al. (2026). Low-Dose Buprenorphine Following Ketamine Treatment for Suicidal Ideation in Major Depressive Disorder: A Randomized, Double-Blind, Placebo-Controlled Trial. American Journal of Psychiatry, 183(6), 409-419. DOI 10.1176/appi.ajp.20250840 · PMID 42151794. Source study analyzed here. Funding: NIH, grant K08 DA055157.
Williams NR, Heifets BD, Blasey C, Sudheimer K, Pannu J, Pankow H, et al. (2018). Attenuation of Antidepressant Effects of Ketamine by Opioid Receptor Antagonism. American Journal of Psychiatry, 175(12), 1205-1215. DOI 10.1176/appi.ajp.2018.18020138 · PMID 30153752. A crossover trial in 12 patients with treatment-resistant depression: naltrexone pretreatment abolished ketamine’s antidepressant effect without altering its dissociative effects. The foundational work behind the opioid hypothesis, conducted on the antidepressant rather than the antisuicidal effect, by a team sharing several authors with the study analyzed here.