17α-estradiol

17α-estradiol (alfatradiol) is a naturally occurring stereoisomer of 17β-estradiol, classified as a weak estrogen and used primarily as a topical treatment for androgenetic alopecia (pattern hair loss) in men[1]. Its pharmacological profile includes inhibition of the enzyme 5α-reductase, limiting the conversion of testosterone to dihydrotestosterone (DHT), thus impacting hair growth and androgen signaling[1]. In contrast to 17β-estradiol, 17α-estradiol binds estrogen receptors with lower affinity and has substantially reduced estrogenic (i.e., feminizing) activity, making it potentially useful in males without significant risk of feminization[1][5]. It functions as an agonist at estrogen receptor alpha (ERα), estrogen receptor beta (ERβ), and the brain-specific receptor ER-X, with selective activity particularly in the brain[1][7]. Preclinical studies demonstrate that 17α-estradiol has neuroprotective, anti-inflammatory, and metabolic benefits, including promising activity in models of Alzheimer's and Parkinson's diseases as well as in age-related metabolic dysfunction[1][2][3][4][7][9]. In animal models, 17α-estradiol extends healthspan and lifespan, especially in males, and ameliorates age-related metabolic disease by modulating hypothalamic signaling and reducing inflammation[4][5][6][9].

Brand names

AvicisAvixisEll-Cranell AlphaPantostin

Other names

17α-E2alpha-estradiol17-alpha-estradiolalfatradiol