Pharmacology Of Danazol

Indication	For the treatment of endometriosis and fibrocystic breast disease (in patients unresponsive to simple measures). Also used for the prophylactic treatment of all types of hereditary angioedema in males and females.
Pharmacodynamics	Danazol is a derivative of the synthetic steroid ethisterone, a modified testosterone. It was approved by the U.S. Food and Drug Administration (FDA) as the first drug to specifically treat endometriosis, but its role as a treatment for endometriosis has been largely replaced by the gonadotropin-releasing hormone (GnRH) agonists. Danazol has antigonadotropic and anti-estrogenic activities. Danazol acts as an anterior pituitary suppressant by inhibiting the pituitary output of gonadotropins. It possesses some androgenic properties.
Mechanism of action	As a gonadotropin inhibitor, danazol suppresses the pituitary-ovarian axis possibly by inhibiting the output of pituitary gonadotropins. Danazol also depresses the preovulatory surge in output of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), thereby reducing ovarian estrogen production. Danazol may also directly inhibits ovarian steroidogenesis; bind to androgen, progesterone, and glucocorticoid receptors; bind to sex-hormone-binding globulin and corticosteroid-binding globulin; and increases the metabolic clearance rate of progesterone. Another mechanism of action by which danazol may use to facilitate regression of endometriosis is by decreasing IgG, IgM, and IgA concentrations, as well as phospholipid and IgG isotope autoantibodies. In the treatment of endometriosis, as a consequence of suppression of ovarian function, danazol causes both normal and ectopic endometrial tissues to become inactive and atrophic. This leads to anovulation and associated amenorrhea. In fibrocystic breast disease, the exact mechanism of action of danazol is unknown, but may be related to suppressed estrogenic stimulation as a result of decreased ovarian production of estrogen. A direct effect on steroid receptor sites in breast tissue is also possible. This leads to a disappearance of nodularity, relief of pain and tenderness, and possibly changes in the menstrual pattern. In terms of hereditary angioedema, danazol corrects the underlying biochemical deficiency by increasing serum concentrations of the deficient C1 esterase inhibitor, resulting in increased serum concentrations of the C4 component of the complement system. (Source: PharmGKB)
Absorption	Not Available
Volume of distribution	Not Available
Protein binding	Not Available
Metabolism	Hepatic, to principal metabolites, ethisterone and 17-hydroxymethylethisterone.
Route of elimination	Not Available
Half life	Approximately 24 hours.
Clearance	Not Available
Toxicity	Not Available