A 17-oxo steroid that is androst-4-ene-3,17-dione in which the hydrogen at position 4 is replaced by a hydroxy group. Formestane was the first selective, type I steroidal aromatase inhibitor, suppressing oestrogen production from anabolic steroids or prohormones. It was formerly used in the treatment of oestrogen-receptor positive breast cancer in post-meopausal women. As it has poor oral bioavailability, it had to be administered by (fortnightly) intramuscular injection. It fell out of use with the subsequent development of cheaper, orally active aromatase inhibitors. Formestane is listed by the World Anti-Doping Agency as a substance prohibited from use by athletes.
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This entity has been manually annotated by the ChEBI Team.
An EC 1.14.14.* (oxidoreductase acting on paired donors, incorporating of 1 atom of oxygen, with reduced flavin or flavoprotein as one donor) inhibitor which interferes with the action of aromatase (EC 1.14.14.14) and so reduces production of estrogenic steroid hormones.
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