What Is Brexanolone (Zulresso)?
Brexanolone, sold as Zulresso, was the first medication approved by the U.S. Food and Drug Administration (FDA) specifically for postpartum depression. It was approved in 2019 and given as a 60-hour continuous IV infusion under medical supervision.
Is Zulresso Still Available?
No. According to the FDA, as of January 1, 2025, Zulresso is no longer commercially available in the United States, and FDA’s drug database lists it as discontinued. In March 2025, the FDA announced it was withdrawing the drug’s approval, effective April 14, 2025, after the manufacturer told the agency the drug was no longer marketed and asked for the withdrawal. It was not described as a safety action.
If you are looking for a fast-acting medication designed for postpartum depression today, the related oral drug Zurzuvae (zuranolone) is available as a 14-day pill. Standard antidepressants and therapy are also effective.
How Brexanolone Works
Brexanolone is the pharmaceutical form of allopregnanolone, a natural hormone made from progesterone. Allopregnanolone levels rise during pregnancy and drop quickly after birth. Brexanolone boosts the activity of GABA-A receptors, which help calm brain activity. The FDA label notes that exactly how it treats postpartum depression is not fully understood.
It had to be given by IV because less than 5% of it is absorbed when taken by mouth.
How the Infusion Was Given
- A single continuous IV infusion over 60 hours (2.5 days), with the dose increased in steps and then tapered down.
- Given in a certified health care facility with a provider on site to monitor continuously.
- Continuous pulse oximetry with an alarm, plus checks for sedation every 2 hours while awake.
- Patients had to be accompanied when caring for their children during the infusion.
- It was available only through a restricted safety program called the ZULRESSO REMS.
In 2022, the FDA expanded approval from adults to patients 15 years and older, based on adult effectiveness data plus drug-level and safety data in teens.
How Well Did It Work?
Two randomized trials, published in The Lancet in 2018, tested brexanolone against placebo:
- Severe postpartum depression (138 women): by the end of the 60-hour infusion, depression scores dropped by 17.7 to 19.5 points with brexanolone, depending on the dose, compared with 14.0 points with placebo.
- Moderate postpartum depression (108 women): scores dropped by 14.6 points with brexanolone versus 12.1 with placebo.
The improvement was rapid, measured within about two and a half days, and the trials also looked at whether it lasted to day 30. The trials were small by modern standards.
Side Effects and Safety Warnings
Boxed Warning: Sedation and Loss of Consciousness
- About 4% of patients lost consciousness or had an altered state of consciousness during the infusion, compared with 0% on placebo. They recovered within 15 to 60 minutes after the infusion was paused.
- 5% needed their infusion paused or lowered because of sedation.
- Not everyone who lost consciousness felt sleepy beforehand, which is why continuous monitoring was required.
Common Side Effects
At the recommended dose, common side effects compared with placebo included:
- Sleepiness or sedation: 13% vs. 6%
- Dizziness or feeling faint: 12% vs. 7%
- Dry mouth: 3% vs. 1%
- Fast heart rate: 3% vs. 0%
- Flushing or hot flashes: 2% vs. 0%
Only 2% of patients stopped treatment because of side effects. Brexanolone is a Schedule IV controlled substance.
Brexanolone and Breastfeeding
- The amount reaching a breastfed baby was estimated at about 1% to 2% of the mother’s weight-adjusted dose, and very little would be absorbed by the baby.
- Milk levels were mostly undetectable about 3 days after the infusion ended.
- LactMed stated brexanolone would not be expected to harm breastfed infants and was not a reason to stop breastfeeding, though no published data exist on outcomes in breastfed babies.
Brexanolone vs. Zurzuvae
| Brexanolone (Zulresso) | Zuranolone (Zurzuvae) | |
| Availability | Discontinued in the U.S. January 1, 2025 | Available by prescription |
| How it’s given | 60-hour IV infusion in a certified facility | Pill once daily for 14 days at home |
| Approved ages | 15 and older | Adults |
| Main safety warning | Sudden loss of consciousness; REMS program | Driving impairment; no driving for 12 hours after a dose |
| Half-life | About 9 hours | About 20 to 25 hours |
Both drugs were developed by Sage Therapeutics and act on the same brain receptors. No trial has compared them head to head.
Treatment Options Today
If you have postpartum depression, effective treatments are available:
- Zurzuvae (zuranolone), a 14-day oral medication
- SSRIs and other antidepressants, many of which are used while breastfeeding
- Therapy, such as cognitive behavioral therapy and interpersonal therapy
Find a postpartum depression specialist near you
Call or text the National Maternal Mental Health Hotline at 1-833-TLC-MAMA (1-833-852-6262), 24 hours a day. If you have thoughts of harming yourself, call or text 988.
Frequently Asked Questions
Is Zulresso still available?
No. Zulresso stopped being commercially available in the U.S. on January 1, 2025, and the FDA withdrew its approval at the manufacturer’s request effective April 14, 2025.
What replaced brexanolone?
Zurzuvae (zuranolone), a related oral medication from the same developer, has been available since late 2023. The FDA notice says only that the manufacturer stopped marketing Zulresso and requested the withdrawal.
How long was the brexanolone infusion?
60 hours, or two and a half days, given continuously by IV with monitoring.
Was brexanolone withdrawn for safety reasons?
No. The FDA’s withdrawal notice states the manufacturer requested it because the drug was no longer marketed.
What were the side effects of brexanolone?
The most serious was sudden loss of consciousness in about 4% of patients. Common side effects included sleepiness, dizziness, dry mouth and flushing.
