How to Select Patients for Zuranolone in Major Depressive Disorder
How can clinicians identify adult outpatients with major depressive disorder who most closely resemble the patients with the strongest zuranolone 30 mg signal in MOUNTAIN?
Clinicians considering a short-course rapid-onset treatment strategy for major depressive disorder need to know which patients in this trial looked most likely to benefit and which patients were excluded. In MOUNTAIN, the overall phase 3 primary endpoint was negative, but the strongest signal with zuranolone 30 mg appeared early and was more evident in patients with greater baseline severity and measurable drug exposure.
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Confirm that the patient matches the studied population
Start with adult outpatients aged 18 to 65 years who have major depressive disorder confirmed in the study with SCID-5-CT. Symptoms had to be present for at least 4 weeks. The trial evaluated short-course oral treatment in outpatients rather than inpatient or highly supervised administration.
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Establish a sufficiently severe depressive episode
Use symptom severity thresholds that align with the modified full analysis set, because the protocol was amended to better capture the intended population. The study ultimately required both MADRS of 32 or higher and HDRS-17 of 22 or higher at screening and again on day 1 before dosing. Post hoc analyses showed the clearest day 15 signal in patients with baseline HDRS-17 of 24 or higher.
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Screen for key exclusion features used in the trial
Do not model this trial's findings onto patients with attempted suicide associated with the current major depressive disorder episode, treatment-resistant depression, active psychosis, bipolar disorder, schizophrenia, schizoaffective disorder, seizure history, pregnancy, being within 4 weeks postpartum, or substance use disorder diagnosed within 12 months before screening. In this study, treatment-resistant depression meant persistent depressive symptoms despite adequate doses of 2 different antidepressant classes during the current episode for at least 4 weeks, excluding antipsychotics.
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Review concurrent antidepressant use for stability
If the patient is already taking an antidepressant, the study allowed this only when the dose had been stable for at least 60 days before day 1. Participants also had to agree to continue that stable dose through day 42. New antidepressants or other medications thought to affect efficacy or safety endpoints were not allowed between screening and completion of day 42 assessments.
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Use the studied dose and administration conditions
The efficacy signal in this trial was with zuranolone 30 mg, not 20 mg. Patients self-administered a single oral dose once daily in the evening with food, preferably a fat-containing meal to increase absorption, for 14 days. Dose adjustments were not permitted in the study.
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Assess early response rather than waiting only for day 15
If you are interpreting this trial clinically, focus on the early-treatment window. In the modified full analysis set, zuranolone 30 mg separated from placebo on HDRS-17 at day 3, day 8, and day 12, but not on the primary endpoint at day 15. Response rates with zuranolone 30 mg were also significantly higher than placebo at day 8 and day 12.
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Prioritize adherence and confirm drug exposure when possible
The paper suggests that nonadherence may have diluted efficacy estimates, because 30 of 338 patients assigned to zuranolone had no measurable postbaseline plasma concentration. In post hoc analysis, excluding patients without measurable concentration produced a significant day 15 benefit for zuranolone 30 mg versus placebo. Patients with both HDRS-17 of 24 or higher at baseline and measurable plasma zuranolone concentration had the largest post hoc day 15 separation from placebo.
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Monitor tolerability and suicidality during and after the 14-day course
Safety monitoring in the study included adverse event reporting, the Columbia-Suicide Severity Rating Scale, the Physician Withdrawal Checklist, and standard clinical assessments. Common treatment-emergent adverse events with zuranolone 30 mg included fatigue, somnolence, headache, diarrhea, dizziness, sedation, and nausea. Serious adverse events were uncommon, but one suicide attempt occurred on day 5 in the 30 mg group and was considered possibly drug-related.
Clinical Considerations
- MOUNTAIN did not meet its prespecified primary endpoint, so this guide identifies patients resembling the strongest signal subgroup rather than a definitively proven responder profile.
- The stronger findings for baseline HDRS-17 of 24 or higher and for measurable plasma zuranolone concentration came from post hoc analyses.
- About 8.9% of patients assigned to zuranolone had no measurable postbaseline plasma concentration, which the authors note could indicate nonadherence and may limit interpretation.
- Stringent inclusion and exclusion criteria and mid-study eligibility amendments limit generalizability to all patients with major depressive disorder.
Bottom Line
If using MOUNTAIN to guide clinical selection, the best-supported fit is an adherent adult outpatient with non-treatment-resistant major depressive disorder, high baseline symptom severity, stable concomitant antidepressant therapy if present, and use of zuranolone 30 mg once nightly with food for 14 days.
