Danazol is a derivative of the synthetic steroidethisterone that suppresses the production of gonadotrophins and has some weak androgenic effects. Before becoming available as a generic drug, danazol was marketed as Danocrine in the United States. It was approved by the US Food and Drug Administration (FDA) as the first drug to specifically treat endometriosis in the early 1970s. Although effective for endometriosis, its use is limited by its masculinizing side-effects. Its role as a treatment for endometriosis has been largely replaced by the GnRH agonists.
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.
Androgenic side effects are of concern, as some women taking danazol may experience unwanted hair growth (hirsutism), acne, deepening of the voice (sometimes irreversible), or adverse blood lipid profiles. Danazol may also cause hot flashes, elevation of liver enzyme levels, and mood changes. Some patients who use danazol experience weight gain and fluid retention. Due to these limitations, danazol is seldom prescribed continuously beyond six months.
The use of danazol for endometriosis has been linked to an increased risk of ovarian cancer. Patients with endometriosis have specific risk factors for ovarian cancer, so this may not apply for other uses.
Danazol, like most other androgenic agents, has been linked with an increased risk of liver tumors. These are generally benign.
Unlike GnRH agonists, danazol does not induce osteoporosis. Also, symptoms of hot flushes tend to be less common or severe.
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^Cottreau CM, Ness RB, Modugno F, Allen GO, Goodman MT (2003). "Endometriosis and Its Treatment with Danazol or Lupron in Relation to Ovarian Cancer". Clinical Cancer Research9 (14): 5142–4. PMID14613992.
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