In March 2019, the Food and Drug Administration approved a novel medication, Zulresso (brexanolone), for the treatment of postpartum depression. Brexanolone is the first FDA-approved medication for the treatment of postpartum depression, a serious illness that affects nearly one in nine women soon after giving birth.1
Mothers with postpartum depression experience feelings of sadness, irritability, and anxiety, as well as isolation from their loved ones (including their new baby) and exhaustion. The feelings of sadness and anxiety can be extreme, and can interfere with a woman’s ability to care for herself or her family. In some cases, these symptoms can be life threatening. Indeed, the most common cause of maternal death after childbirth in the developed world is suicide.2 Because of the severity of the symptoms and their impact on the family, postpartum depression usually requires treatment.
Until now, there have been no drugs specifically approved to treat postpartum depression. Commonly, postpartum depression is treated with medications that previously were approved for the treatment of major depressive disorder, despite limited evidence documenting their efficacy for postpartum depression. Other putative treatment alternatives include, , and neuromodulation, such as and . Each of these treatments can take weeks or longer to take effect, time that is of elevated importance given the rapidly developing mother-infant relationship in the early postpartum period. Brexanolone addresses both the issue of efficacy and speed of onset, representing a major step forward in the care of women suffering from postpartum depression.
Importantly, the approval of brexanolone marks an important milestone for the psychiatric research community in general and the National Institute of Mental Health in particular, as it represents a compelling example of successful bench-to-bedside translation of basic neuroscience findings to benefit patients. As we have noted elsewhere,3 the research underlying the discovery of endogenous neurosteroids and their role in modulating GABA receptors laid the foundation for the development of brexanolone, an intravenous formulation of the neurosteroid allopregnanolone. The recognition that allopregnanolone was a protective factor induced by stress, that it derived from progesterone, and that its peripheral blood levels were dramatically reduced in the early postpartum period led to the hypothesis that it might be useful as a treatment for postpartum depression.
Sage Therapeutics took on the task of testing this hypothesis, designing a program, in consultation with the FDA, to test the efficacy of allopregnanolone in women with postpartum depression in a series of randomized, placebo-controlled studies assessing brexanolone.4,5 It is a significant accomplishment of Sage Therapeutics to not only successfully complete the therapeutic program of studies (given past experience with difficulties recruiting these women for placebo-controlled treatment trials) but as well to demonstrate a robust therapeutic effect.
Although the FDA’s approval of a new and novel treatment is exciting for many women, there are still limitations to the broader use of brexanolone. It is delivered intravenously, requires an overnight stay in a certified medical center, and is likely to be considerably expensive, according to– potentially limiting the access to the treatment. There also are potentially serious side effects, such as sedation, dizziness, or sudden loss of consciousness. Nonetheless, this is a promising first step and hopefully will spur further efforts to identify and optimize additional strategies to treat postpartum depression. In fact, other formulations of allopregnanolone and novel analogs to treat postpartum depression already are under study, including some that are orally bioavailable.6,7,8
Several important questions remain to be answered about both brexanolone and postpartum depression: What is the underlying mechanism through which allopregnanolone acts in the brain and reduces depressive symptoms? Is the mechanism unique to postpartum women, or might brexanolone also be effective in nonreproductive depressions in women and men? What causes postpartum depression, and what are the risk factors involved for women who develop this serious condition? Future work will focus on these and other important questions to the benefit of women who have suffered with this condition.
The FDA approval of brexanolone represents the second approval in a month of a new antidepressant treatment targeting different molecules in the brain. In early March 2019, the agency approved Spravato (esketamine) nasal spray as a therapy for treatment-resistant depression. Like brexanolone, esketamine is a fast-acting antidepressant that works through a novel mechanism, completely different from other antidepressants. These new treatment approvals are encouraging, as there has been a paucity for many years in approving new effective treatments for mood disorders.
However, treatment development in psychiatry still has a long way to go and the full underlying neurobiology of mood disorders, including postpartum depression, remains poorly understood. Many challenges are ahead of us in our efforts to develop new treatments and increase our understanding of mental illnesses. Nevertheless, the approval of brexanolone is an important milestone, giving hope to the many women who suffer from postpartum depression, and paving the way for the development of additional novel and effective medications to treat this serious and sometimes life-threatening condition.