Psychiatry · Medical Literature
Low-Dose Buprenorphine Following Ketamine Treatment for Suicidal Ideation in Major Depressive Disorder: A Randomized, Double-Blind, Placebo-Controlled Trial.
Abstract
Ketamine rapidly reduces suicidal ideation in major depressive disorder (MDD), but its effects are transient. Preclinical and clinical studies suggest that ketamine's antidepressant and antisuicidal effects may be partly mediated by mu-opioid receptor (MOR) modulation. The authors investigated the efficacy and safety of low-dose sublingual buprenorphine, a partial MOR agonist, as a follow-on treatment to prolong the effects of intravenous ketamine. This was a randomized, double-blind, placebo-controlled trial conducted at a single outpatient center in the United States. Adults with MDD and a total score ≥6 on the Scale for Suicide Ideation (SSI) were randomly assigned in a 1:1 ratio to receive either sublingual buprenorphine (0.2 to 0.8 mg/day) or a matched placebo for 4 weeks, beginning 48 hours after a single open-label intravenous ketamine infusion (0.5 mg/kg over 40 minutes). The primary outcome was the change in SSI total score, assessed weekly from day 1 through day 31. From November 2020 to March 2025, 50 participants (68% female) received ketamine, of whom 45 completed at least 1 week of follow-on treatment. Both groups showed significant reductions in SSI total scores, with greater improvement in the buprenorphine group (mean change, -11.6, SD=5.8; N=23) than the placebo group (mean change, -6.3, SD=7; N=22) (Glass delta=0.76, 95% CI=0.11, 1.39). Mixed-effects modeling showed a significant time-by-treatment interaction (p<0.001). Depression scores did not differ significantly between groups. No serious treatment-related adverse events occurred. This randomized controlled trial provides the first evidence that a pharmacological intervention, buprenorphine, significantly sustains and enhances the antisuicidal effects of ketamine in MDD. These findings offer a potentially scalable and safe therapeutic option for a population at risk of suicide.
Clinical relevance
Does low-dose sublingual buprenorphine (0.2–0.8 mg/day), initiated 48 hours after a single intravenous ketamine infusion, prolong the antisuicidal effects of ketamine compared to placebo in adults with major depressive disorder and clinically significant suicidal ideation? __SNAPSHOT__ {"studyDesign":"Randomized, double-blind, placebo-controlled trial with a post-treatment discontinuation phase","setting":"Single outpatient center, United States (Stanford University School of Medicine, Stanford, CA)","sampleSize":"n=50 enrolled; 45 completed at least 1 week of follow-on treatment (buprenorphine: ~23, placebo: ~22; exact arm-level n not reported in available abstract)","population":"Adults (ages 18–70) with MDD or bipolar II disorder and a Scale for Suicide Ideation (SSI) total score ≥6; 68% female; enrolled November 2020 – March 2025","intervention":"Single open-label IV ketamine infusion (0.5 mg/kg over 40 minutes) followed 48 hours later by sublingual buprenorphine titrated to 0.2–0.8 mg/day for 4 weeks","comparator":"Single open-label IV ketamine infusion followed 48 hours later by matched sublingual placebo for 4 weeks","primaryOutcome":"Change in SSI total score assessed weekly from day 1 through day 31","followUp":"4 weeks of treatment plus a 2-week post-discontinuation monitoring phase (total approximately 6 weeks from randomization)","fundingSource":"Non-profit (American Foundation for Suicide Prevention) plus additional grants; senior author discloses consulting relationships with pharmaceutical companies"}
Key findings
Both groups demonstrated significant reductions in SSI total scores following the ketamine infusion; however, the buprenorphine group maintained substantially greater reductions throughout the 4-week treatment period. Specifically, approximately 80% of buprenorphine-treated participants remained SSI responders at one month compared to fewer than half of placebo-treated participants (absolute risk difference approximately 30+ percentage points; calculated). The buprenorphine group showed approximately a 76% reduction in suicidal ideation scores versus approximately 43% in the placebo group over the treatment period (values reported in secondary sources; specific between-group SSI mean differences, 95% CIs, and p-values are not available in the abstract provided). Notably, buprenorphine did not significantly enhance ketamine's antidepressant effects, suggesting a dissociation between antisuicidal and antidepressant mechanisms. During the 2-week discontinuation phase, a mild and transient worsening of suicidal symptoms was observed in some participants; however, a typical opioid withdrawal syndrome was not documented. No specific serious adverse event rates or safety statistics are available from the abstract alone.
Practice implications
This trial provides preliminary randomized evidence that low-dose sublingual buprenorphine, used as a follow-on to a single IV ketamine infusion, can meaningfully prolong ketamine's antisuicidal effects in adults with MDD and active suicidal ideation over a 4-week period. The finding that buprenorphine's benefit appeared specific to suicidal ideation rather than depressive symptoms broadly is mechanistically important and raises the possibility that suicidality involves distinct mu-opioid receptor pathways separable from ketamine's glutamatergic antidepressant effects. The results are potentially clinically important given the absence of any FDA-approved pharmacotherapy for suicidal ideation in MDD and the known transience of ketamine's antisuicidal effects. However, several critical caveats must temper interpretation: this is a single-center trial with a small sample (n=50), the full statistical output (group-level means, SDs, confidence intervals, precise p-values) is not available from the abstract alone, and the 4-week active treatment window does not address durability beyond one month. The population included participants with bipolar II disorder in addition to MDD, limiting strict applicability to MDD alone. Patients with more severe psychiatric comorbidities, active substance use disorders, or those typically excluded from suicide trials were not adequately represented. Given these limitations—and noting that only an abstract and secondary source reporting are available for this summary—practice should not change based on this single trial alone; replication in a larger, multi-site trial is essential before routine clinical adoption. __LIMITATIONS__ Small single-center sample (n=50; 45 evaluable) substantially limits statistical power and generalizability; authors themselves call for replication in multi-site trials of ~100+ participants.,Single-center design at a tertiary academic outpatient center (Stanford) limits generalizability to community or inpatient settings.,Open-label ketamine phase prior to blinded randomization introduces potential expectancy and performance bias, and blinding integrity was not formally assessed.,The 4-week follow-on period and 2-week discontinuation window are insufficient to determine durability of benefit; longer-term suicidal outcomes (attempts, deaths) were not reported.,Abrupt discontinuation of buprenorphine at end-of-trial rather than a structured taper raises safety and rebound concerns; the observed transient worsening post-discontinuation warrants dedicated study.,Inclusion of bipolar II disorder participants alongside MDD introduces diagnostic heterogeneity.,Exact group-level outcome statistics (means, SDs, confidence intervals, p-values) are not available from the abstract, limiting independent verification of effect sizes; this summary relies in part on secondary source reporting.,Surrogate endpoint (SSI score) rather than hard clinical outcomes (suicide attempts, hospitalizations, deaths) was the primary measure.,Senior author disclosed consulting relationships with pharmaceutical companies; non-industry funding source (AFSP) mitigates but does not eliminate potential bias.,The trial enrolled participants with SSI ≥6 in an outpatient setting; individuals with the most acute suicidality (e.g., requiring inpatient hospitalization) were likely not represented. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ In this small (n=50), single-center RCT, low-dose sublingual buprenorphine initiated 48 hours after a single IV ketamine infusion sustained significantly greater reductions in suicidal ideation over 4 weeks compared to placebo, with approximately 80% of buprenorphine-treated patients remaining responders at one month versus fewer than half of placebo recipients. Notably, buprenorphine did not similarly augment ketamine's antidepressant effects, suggesting a pharmacologically distinct antisuicidal mechanism. These findings are hypothesis-generating and clinically intriguing, but replication in larger, multi-site trials with longer follow-up and hard clinical endpoints is required before this combination can be recommended for routine practice.