What molecule am I?
Allopregnanolone, also commonly called brexanolone, is a metabolite of the sex hormone progesterone that is produced in the brains of mammals. It was first isolated from the urine of pregnant women in 1937 by Russell E. Marker, Oliver Kamm, and Ralph V. McGrew at Penn State (State College, PA) and Parke-Davis (Detroit). The following year, G. Fleischer, B. Whitman, and E. Schwenk at Schering (Bloomfield, NJ) synthesized it from the hormone pregnenolone.
Allopregnanolone modulates the γ-aminobutyric acid (GABA) receptor GABAA in the brain. In 2019, the US Food and Drug Administration approved allopregnanolone as an intravenous infusion for treating postpartum depression (PPD; see the sidebar), the first drug to be approved for this condition. Sage Therapeutics (Cambridge, MA) markets it under the trade name Zulresso.
The 60-h Zulresso infusion reduces the symptoms of PPD almost immediately. Because the patient must be closely monitored, the drug must be administered in a medical facility.
Postpartum depression
Childbirth causes hormonal fluctuations that interact with the host of emotions that accompany the birth of a baby: excitement, joy, fear, anxiety, and even depression. The fear, anxiety, and depression are often described as the baby blues and last from a few days to a couple of weeks.
A more serious complication of birth can be a debilitating depression—postpartum depression, or PPD—which can last for weeks or months. Because most antidepressants can take a few weeks to become effective, the development of a faster-acting medication that specifically targets the hormonal aspects of PPD is significant.
Allopregnanolone hazard information
| Hazard class* | Hazard statement |
|---|---|
| Not a hazardous substance or mixture |
*Globally Harmonized System of Classification and Labeling of Chemicals.
Allopregnanolone fast facts
| CAS Reg. No. | 516-54-1 |
| SciFinder nomenclature | Pregnan-20-one, 3-hydroxy-, (3α,5α)- |
| Empirical formula | C21H34O2 |
| Molar mass | 318.49 g/mol |
| Appearance | White crystalline solid |
| Melting point | 177 ºC |
| Water solubility | Very slight |
Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.
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