indication

In males, used as replacement therapy in conditions associated with symptoms of deficiency or absence of endogenous testosterone. In females, for palliation of androgenresponsive recurrent mammary cancer in women who are more than one year but less than five years postmenopausal.

pharmacology

Fluoxymesterone is a synthetic androgen, or male hormone, similar to testosterone. Fluoxymesterone works by attaching itself to androgen receptors; this causes it to interact with the parts of the cell involved in the making of proteins. It may cause an increase in the synthesis of some proteins or a decrease in the synthesis of others. These proteins have a variety of effects, including blocking the growth of some types of breast cancer cells, stimulating cells that cause male sexual characteristics, and stimulating the production of red blood cells.

mechanism of action

Fluoxymesterone is a synthetic androgenic anabolic steroid and is approximately 5 times as potent as natural methyltestosterone. Like testosterone and other androgenic hormones, fluoxymesterone binds to the androgen receptor. It produces retention of nitrogen, sodium, potassium, and phosphorus; increases protein anabolism; decreases amino acid catabolism and decreased urinary excretion of calcium. The antitumour activity of fluoxymesterone appears related to reduction or competitive inhibition of prolactin receptors or estrogen receptors or production.

toxicity

Side effects include virilization (masculine traits in women), acne, fluid retention, and hypercalcemia.

biotransformation

Presence of 17-alpha alkyl group reduces susceptibility to hepatic enzyme degradation, which slows metabolism and allows oral administration. Inactivation of testosterone occurs primarily in the liver

absorption

Oral absorption is less than 44%.

half life

9.2 hours

drug interactions

Acenocoumarol: The androgen, fluoxymesterone, may increase the anticoagulant effect of acenocoumarol.

Anisindione: The androgen, fluoxymesterone, may increase the anticoagulant effect of anisindione.

Dicumarol: The androgen, fluoxymesterone, may increase the anticoagulant effect of dicumarol.

Warfarin: Fluoxymesterone may increase the serum concentration and anticoagulant effect of warfarin. Monitor for changes in prothrombin time and therapeutic effects of warfarin if fluoxymesterone is initiated, discontinued or dose changed.