Gestrinone

Gestrinone is approved for and used in the treatment of endometriosis. It is described as similar in action and effect to danazol, which is also used in the treatment of endometriosis, but is reported to have fewer androgenic side effects in comparison. Gestrinone has also been used to shrink uterine fibroids and to reduce menorrhagia. Due to its antigonadotropic effects and ability to inhibit ovulation, gestrinone has been studied as a method of hormonal birth control in women. ==Contraindications==

The medication is contraindicated in pregnancy, during lactation, and in patients with severe cardiac, chronic kidney disease or liver disease. It is also contraindicated in patients who experienced metabolic and/or vascular disorders during previous estrogen or progestogen therapy, or who are allergic to the medication. The medication is contraindicated in children. ==Side effects==

The main side effects of gestrinone are androgenic and antiestrogenic in nature. Gestrinone also inhibits gonadotropin secretion and causes amenorrhea or oligomenorrhea in a high percentage of women. Similarly, circulating estradiol levels have been found to be reduced by 50%, which may result in estrogen deficiency and associated symptoms. Studies of 2.5 mg oral gestrinone twice per week have found a rate of amenorrhea of 50 to 58%, while a study of 5 mg oral gestrinone per day found a rate of amenorrhea of 100%. It has been found that vaginal gestrinone shows fewer androgenic side effects and weight gain than oral gestrinone with equivalent effectiveness in endometriosis. Gestrinone appears to show similar effectiveness to danazol in the treatment of endometriosis but with fewer side effects, in particular androgenic side effects. ==Pharmacology==

Pharmacodynamics The mechanism of action of gestrinone is complex and multifaceted. In addition to the PR and AR, gestrinone has been found to bind to the estrogen receptor (ER) with relatively "avid" affinity. The medication has functional antiestrogenic activity in the endometrium. Unlike danazol, gestrinone does not appear to bind to SHBG or corticosteroid-binding globulin (CBG). Pharmacokinetics Gestrinone is bound to albumin in the circulation. It is metabolized in the liver mainly by hydroxylation. Four hydroxylated active metabolites with reduced activity relative to gestrinone have been found to be formed. The elimination half-life of gestrinone is 27.3 hours. The medication is excreted in urine and bile. ==Chemistry==

Gestrinone, also known as 17α-ethynyl-18-methyl-19-nor-δ9,11-testosterone, as well as 17α-ethynyl-18-methylestra-4,9,11-trien-17β-ol-3-one or as 13β-ethyl-18,19-dinor-17α-pregna-4,9,11-trien-20-yn-17β-ol-3-one, is a synthetic estrane steroid and a derivative of testosterone. Gestrinone is the C18 methyl derivative of norgestrienone (17α-ethynyl-19-nor-δ9,11-testosterone) and the δ9,11 analogue of levonorgestrel (17α-ethynyl-18-methyl-19-nortestosterone) and is also known as ethylnorgestrienone due to the fact that it is the C13β ethyl variant of norgestrienone. It is also the C17α ethynyl and C18 methyl derivative of the AAS trenbolone. The androgenic properties of gestrinone are more exploited in its derivative tetrahydrogestrinone (THG; 17α-ethyl-18-methyl-δ9,11-19-nortestosterone), a designer steroid which is far more potent as both an AAS and progestogen in comparison. THG was banned by the Food and Drug Administration (FDA) in 2003. ==History==

Gestrinone was introduced for medical use in 1986. ==Society and culture==

Generic names Gestrinone is the generic name of the drug and its , , , and . It is also known by its developmental code names A-46745 and R-2323 (or RU-2323). ==References==