Fluoxymesterone (trade name Halotestin) is an anabolic steroid with strong androgenic properties that has been used in the treatment of male hypogonadism, delayed puberty in males, and in the treatment of breast neoplasms in women. It is approximately 5 times as potent as methyltestosterone.[citation needed] The antitumor activity of fluoxymesterone appears related to reduction or competitive inhibition of prolactin receptors or estrogen receptors or production.[citation needed]
Like many C-17 alpha alkylated steroids, fluoxymesterone has poor binding to the androgen receptor. Even so, its actions are mediated by the androgen receptor, most-likely due to its prolonged plasma half-life.[1]
It is considered a very toxic oral drug.
Though the half-life of fluoxymesterone is about 9.2 hours.[citation needed]