Androgenetic alopecia or pattern hair loss is a dihydrotestosterone-mediated process, The aim of AGA treatment is to reverse or to stop the process of HF miniaturization.

Currently available systemic treatment options for AGA therefore involve either the use of antiandrogens such as cyproterone acetate in women, or steroidogenic enzyme inhibitors such as finasteride in men.

For the topical treatment of AGA, solutions containing either estradiol benzoate, estradiol valerate, 17beta- or 17alpha estradiol are commercially available in Europe and some studies show an increased anagen and decreased telogen rate after treatment as compared to placebo [3]. At present it is not precisely known how estrogens mediate their beneficial effect on pattern hiar loss. In guinea pigs estrogens have been shown to prolong anagen, but in contrast topical application of 17beta-E to the clipped dorsal skin of mice arrested HF in telogen produced a profound and prolonged inhibition of hair regrowth, while treatment with the biologically inactive stereoisomer, 17alpha-E, had no effect. snip… Estrogens at very high concentrations have been found to be non-competitive inhibitors of 5alpha-R. Other groups did not confirm these data when using skin fibroblasts. Moreover, in nearly all experiments showing that estrogens are able to inhibit 5alpha-R in vitro, an inhibition was only present at very high doses of estrogen. One study indicated that 17alpha-E at very high concentrations inhibits 5alpha-R in female rats.

Thus, the use of estrogens for the treatment of pattern hair loss is a treatment option which might be able to stop or reverse hair loss, but the exact success rates and the underlying mechanisms are unknown or open to question….