On March 19, 2019, the FDA approved Zulresso (brexanolone) injection for the treatment of post-partum depression in adult women. Brexanolone is administered as a continuous IV infusion for 60 hours. The approved dose is 90 ug/kg h, although the drug should be initiated at a rate of 30 ug/kg hr and titrated to the target dose gradually.   Because of the risk of excessive sedation and sudden loss of consciousness, brexanolone is administered in a health care facility with continuous monitoring.  Brexanolone is only available via the REMS program. 

Efficacy was evaluated in two randomized, placebo controlled phase III clinical trials enrolling a total of 246 subjects.  Patients were randomly assigned (1:1:1) to receive a single intravenous injection of either brexanolone 90 μg/kg per h, brexanolone 60 μg/kg per h, or matching placebo for 60 h in study 1, or (1:1) brexanolone 90 μg/kg per h or matching placebo for 60 h in study 2.  The primary endpoint was change in change in depression score.  In both studies, brexanolone was significantly better than placebo in improving depression symptoms. Symptoms improved during the infusion and effects persisted 30 days after the start of the infusion.

Brexanolone has black box warnings for severe sedation and loss of consciousness, which occurred in 5% of patients, which was managed by stopping the infusion with symptoms resolving in 90 minutes of less.   The most common adverse effects reported in the clinical trials were headache, dizziness, nausea, sedation, dry mouth and infusion site pain.

While inconvenient and expensive to administer, requiring an inpatient admission, brexanolone is well tolerated and effective with responses persisting at least 30 days and can be considered  a major advance in treating moderate and severe post-partum depression.  

Read more at:

FDA approval

Meltzer-Brody S, etal.  Brexanolone injection in post-partum depression: two multicentre, double-blind, randomised, placebo-controlled, phase 3 trials. Lancet. 2018 Sep 22;392(10152):1058-1070.

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