Allopregnanolone

Allopregnanolone
Ed (Edgar181) · Public domain · source
Tradename	Brexanolone (example)
Routes of administration	Intravenous, Oral (investigational)
Class	Neurosteroid
Metabolism	Hepatic
Elimination half-life	~9 h (brexanolone)
Cas number	516-53-2

Allopregnanolone is a naturally occurring neuroactive steroid derived from Progesterone that modulates neuronal excitability via positive allosteric modulation of Gamma-aminobutyric acid type A receptors, and has been developed pharmaceutically as brexanolone for treatment of postpartum depression. It has been the subject of research across fields including Psychiatry, Neuroscience, Endocrinology, and Pharmacology, and has inspired clinical investigation by companies and institutions such as Sage Therapeutics, National Institutes of Health, and academic centers like Harvard Medical School.

Chemistry and nomenclature

Chemically a 3α-hydroxy-5α-pregnan-20-one steroid, the compound is systematically named 3α-hydroxy-5α-pregnan-20-one and shares structural features with steroids such as Progesterone, Testosterone, and Corticosterone, while differing stereochemically from epimers like Pregnanolone. The molecular scaffold places it within the pregnane family characterized in works from organic chemists at institutions including University of Cambridge and Massachusetts Institute of Technology, and it has been cataloged with identifiers used by bodies like the Chemical Abstracts Service.

Biosynthesis and metabolism

Biosynthesis proceeds from Cholesterol conversion to pregnenolone and onward to Progesterone in steroidogenic tissues such as the Adrenal cortex and Ovary, with enzymatic reduction by 5α-reductase and 3α-hydroxysteroid dehydrogenase producing the neurosteroid; these pathways have been studied in laboratories at Max Planck Society and Stanford University. Hepatic metabolism involves cytochrome P450 enzymes characterized by researchers affiliated with the Food and Drug Administration and European Medicines Agency guidance, and catabolic routes intersect with conjugation pathways described in texts from Johns Hopkins University researchers. Peripheral synthesis in the Placenta and local synthesis in brain regions including the Hippocampus and Amygdala contribute to tissue-specific concentrations examined in clinical studies sponsored by entities like National Institute of Mental Health.

Mechanism of action

Allopregnanolone acts as a positive allosteric modulator of synaptic and extrasynaptic GABAA receptors containing δ and γ subunits, enhancing chloride influx and neuronal inhibition, a mechanism central to anticonvulsant and anxiolytic effects investigated by groups at Columbia University and University College London. It also interacts with membrane receptors and modulates neurogenic and neuroprotective signaling cascades studied in laboratories at Scripps Research and University of California, San Francisco. Electrophysiological effects on inhibitory postsynaptic currents and tonic inhibition have been characterized using methods developed at Yale University and University of Oxford.

Physiological roles and distribution

Concentrations fluctuate across reproductive states, with notable increases during pregnancy in the Third Trimester and rapid postpartum declines documented in cohorts from Cleveland Clinic and Mayo Clinic, implicating the compound in mood regulation and stress responses reviewed by scholars at Princeton University and Columbia University. Brain-region specific distribution has been mapped to the Prefrontal cortex, Hippocampus, and Hypothalamus in autoradiography and mass spectrometry studies conducted at Imperial College London and University of Toronto. Roles in modulating sleep architecture, seizure threshold, and social behavior have been linked to clinical syndromes studied by investigators at University of California, Los Angeles and King's College London.

Clinical uses and therapeutic research

Pharmaceutical development led to approval of an intravenous formulation, brexanolone, for Postpartum depression in regulatory decisions by the United States Food and Drug Administration following trials sponsored by Sage Therapeutics and academic collaborators at Yale School of Medicine. Oral analogs and synthetic neurosteroid modulators have been investigated in trials at institutions such as Stanford University Medical Center and companies including Allergan and Zai Lab for indications including Major depressive disorder, Epilepsy, and Alzheimer's disease. Randomized controlled trials, meta-analyses, and multicenter studies reported in journals associated with American Psychiatric Association and The Lancet have shaped clinical interest and ongoing research programs funded by agencies like the Wellcome Trust and European Commission.

Pharmacology and safety

Pharmacokinetic and pharmacodynamic profiles, including distribution, metabolism, and half-life, were characterized in phase I–III trials overseen by regulatory scientists at the FDA and European Medicines Agency, with safety monitoring involving institutions such as Massachusetts General Hospital and Mount Sinai Health System. Reported adverse effects from intravenous administration include sedation and loss of consciousness, leading to risk-mitigation strategies implemented in hospital settings similar to those developed at Johns Hopkins Hospital. Drug–drug interaction potential via hepatic enzymes has been evaluated in clinical pharmacology units at University of Michigan and Duke University School of Medicine.

History and society

Discovery and structural elucidation trace to steroid chemistry and neuropharmacology advances in mid-20th century laboratories at Rockefeller University and University of Oxford, with translational milestones culminating in regulatory approval processes at the FDA and commercial development by Sage Therapeutics. Public and ethical discussions regarding access, cost, and inpatient infusion requirements have involved stakeholders including American College of Obstetricians and Gynecologists and patient advocacy groups such as Postpartum Support International, and have been covered in media outlets and policy analyses from organizations like The New York Times and The Guardian.

Category:Neurosteroids