Brexanolone and Zuranolone: What Prescribers Need to Know
Written by
Phoenix Health Editorial Team
Expert health information, double-checked for accuracy and written to be helpful.
Last updated
A New Mechanism Class
Brexanolone and zuranolone are the first agents approved specifically for postpartum depression and represent a mechanistically distinct approach from SSRIs and SNRIs. Both are synthetic analogues of allopregnanolone, a neurosteroid that modulates GABA-A receptor function. The mechanism is thought to target the rapid drop in allopregnanolone levels that follows delivery -- a hormonal shift that may be a direct contributor to PPD onset in susceptible patients.
The clinical significance: these agents work faster than SSRIs (response within days rather than weeks), and their mechanism is independent of the monoamine system. For patients who have not responded to SSRIs or who need faster relief, they represent a genuinely different treatment option.
---
Brexanolone (Zulresso)
Approval and indication
FDA-approved in March 2019. Indicated for postpartum depression in adults. First PPD-specific approval in the United States.
Administration
60-hour continuous intravenous infusion. Must be administered in a certified healthcare facility by a REMS-certified provider. The patient remains in the facility for the entire infusion duration.
Clinical trial data
The pivotal trials (Sage-547 studies, published in The Lancet 2018) enrolled patients with moderate-to-severe PPD. Key findings:
- Approximately 70 to 75 percent response rate vs. approximately 55 to 60 percent placebo response
- Remission rates approximately 50 to 55 percent (Hamilton Depression Rating Scale)
- Response onset within the first 24 hours of infusion in most responders
- Effect maintained at 30-day follow-up
Patient selection
Brexanolone is typically reserved for moderate-to-severe PPD with significant functional impairment, given the access and logistics barrier. Strongest candidates:
- Patients needing faster onset than SSRI titration provides
- Patients with previous SSRI non-response in the postpartum period
- Patients with suicidality or acute safety concerns requiring rapid stabilization (though acute suicidality warrants inpatient evaluation independent of brexanolone access)
- Patients who want a non-chronic pharmacological intervention (the 60-hour course rather than ongoing daily medication)
REMS program
The REMS requirement exists because of CNS depression risk (excessive sedation, sudden loss of consciousness) during infusion. Continuous monitoring of oxygen saturation is required. The certified facility requirement is the primary access barrier.
Breastfeeding considerations
Limited data on breastfeeding safety. Current guidance: pump and discard breast milk during the infusion; resume breastfeeding after clearance based on half-life considerations. Discuss with the patient before initiating.
Practical access
The certified facility and REMS requirements mean brexanolone is not available through a standard outpatient prescribing process. Check availability in your network before discussing it as an option with patients. Some academic medical centers and larger perinatal health programs have established infusion capabilities.
---
Zuranolone (Zurzuvae)
Approval and indication
FDA-approved August 2023. Indicated for PPD in adults. First oral agent specifically approved for PPD.
Not approved for major depressive disorder (the FDA declined to approve the MDD indication based on the pivotal trial data); the approval is specific to PPD.
Not a controlled substance (not scheduled under the DEA Controlled Substances Act, despite the GABA mechanism -- a finding that was significant in the approval process).
Administration
50 mg orally once nightly for 14 days, taken with a fatty meal (required for bioavailability). The treatment course is 14 days; no ongoing daily dosing.
Clinical trial data
Pivotal trial: SKYLARK study (2023). Enrolled adults with current moderate-to-severe PPD.
- Significantly greater reduction in Hamilton Depression Rating Scale score vs. placebo at day 15 (primary endpoint)
- Measurable response onset at day 3 in most responders
- Remission rates approximately 52 percent at day 15 vs. approximately 30 percent placebo
- Durability: effects maintained at day 45 follow-up assessment
CNS depression and driving
Zuranolone causes CNS depression. Patients should not drive or operate heavy machinery for 12 hours after each dose. This is a real functional constraint for patients who drive to work or who are primary caregivers without overnight support. Discuss before prescribing and consider whether the patient's life circumstances allow compliance with this limitation.
Patient selection
Zuranolone is appropriate for:
- Moderate-to-severe PPD where rapid onset is a priority
- Patients who prefer a finite course of medication rather than ongoing antidepressant treatment
- Patients who have not responded to SSRIs or who declined SSRIs previously
- Patients with access barriers to brexanolone (no certified facility nearby)
Breastfeeding considerations
Data is limited. Prescribing information recommends avoiding breastfeeding during treatment and for one week after the last dose. For patients who are breastfeeding and want to use zuranolone, a pump-and-discard plan during the 14-day course plus one week after is the current clinical approach.
Concurrent treatment
Clinical evidence supports combining zuranolone with ongoing SSRI therapy in patients who are already on an SSRI. For new-onset PPD, the decision to use zuranolone as monotherapy vs. initiating a concurrent SSRI should account for the expected durability of the zuranolone effect and the patient's prior treatment history.
Insurance and cost
Zuranolone is a brand medication without generic equivalents. Prior authorization is required by most plans. Patient assistance programs are available through the manufacturer. At the time of publication, coverage is variable; verify before prescribing.
---
Comparing the Two Agents
| Feature | Brexanolone | Zuranolone | |---|---|---| | Route | IV infusion (60 hours) | Oral (14-day course) | | Setting | Certified facility (inpatient/outpatient) | Outpatient | | Onset | Hours to 1 day | Days 3–7 | | Access | REMS, limited facilities | Standard prescribing | | Breastfeeding | Pump/discard during infusion | Avoid during treatment + 1 week | | Approved indication | PPD only | PPD only |
---
Where These Agents Fit in Clinical Practice
Neither brexanolone nor zuranolone has displaced SSRIs as standard first-line treatment for PPD. The established safety data, generic availability, and clinical familiarity of SSRIs mean they remain the default in most cases.
The neuroactive steroids are best positioned as:
- A faster-acting option for patients with severe or rapidly deteriorating PPD
- An alternative for SSRI non-responders
- A finite-course option for patients who are reluctant to commit to ongoing medication
- A complement to (rather than replacement for) concurrent psychotherapy and SSRI treatment in severe cases
---
Frequently Asked Questions
This is a clinical judgment question. The SKYLARK trial excluded patients with active bipolar disorder. GABA-ergic agents have theoretical mood-destabilization potential. In patients with bipolar history, consultation with a perinatal psychiatrist is recommended before initiating.
Neither is approved for use during pregnancy, and there is insufficient data to support prenatal use at this time. The allopregnanolone mechanism is specifically tied to postpartum hormonal dynamics; the evidence base is entirely postpartum.
For a patient with moderate-to-severe PPD who needs rapid onset and prefers a finite course, zuranolone is a reasonable first choice. For a patient with mild-to-moderate PPD, good access to therapy, and no urgency for rapid response, an SSRI with concurrent therapy is the better-established option. Patient preference is a legitimate consideration in this decision.
Clinical trials show response maintained at 45 days post-treatment in most responders. For some patients, the 14-day course produces durable remission. For others, symptoms return and ongoing treatment (SSRI or repeat zuranolone course -- the repeat course data is limited) is needed. Frame it honestly: the 14-day course is a fast start; ongoing monitoring and a plan for relapse are part of the treatment plan.
Ready to take the next step?
Our PMH-C certified therapists specialize in exactly this — and most clients are seen within a week.