Danazol is a derivative of the synthetic steroid ethisterone, a modified progestogen, also known as 17-alpha-ethinyl testosterone. Danazol exhibits hypoestrogenic, hyperandrogenic effects that cause atrophy of the endometrium, which can alleviate the symptoms of endometriosis. Danazol prevents ovulation by suppressing the increase of luteinizing hormone during the middle of the menstrual cycle. Danazol inhibits ovarian steroidogenesis resulting in decreased secretion of estradiol and may increase androgens. Danazol displaces testosterone from sex hormone-binding globulin (SHBG), displacing it and increasing serum testosterone levels. Danazol also directly stimulates androgen and progesterone receptors. Danazol is contraindicated during pregnancy because it could masculinize a female fetus. Females taking danazol should also take effective contraceptive therapy to prevent pregnancy.
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