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Progestin

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A progestin is a synthetic[1] progestagen that has progestinic effects similar to progesterone. [2] The two most common uses of progestins are for hormonal contraception (either alone or with an estrogen), and to prevent endometrial hyperplasia from unopposed estrogen in hormone replacement therapy.

Progestins are also used to treat secondary amenorrhea, dysfunctional uterine bleeding and endometriosis, and as palliative treatment of endometrial cancer, renal cell carcinoma, breast cancer, and prostate cancer. High-dose megestrol acetate is used to treat anorexia, cachexia, and AIDS-related wasting.

Progesterone (or sometimes the progestin dydrogesterone or 17-Hydroxyprogesterone caproate) is used for luteal support in IVF (in vitro fertilisation) protocols, questionably for treatment of recurrent pregnancy loss, and for prevention of preterm birth in pregnant women with a history of at least one spontaneous preterm birth.[3]

History

The recognition of progesterone's ability to suppress ovulation during pregnancy spawned a search for a similar hormone that could bypass the problems associated with administering progesterone (low bioavailability when administered orally and local irritation and pain when continually administered parenterally) and, at the same time, serve the purpose of controlling ovulation. The many synthetic hormones that resulted are known as progestins.

The first orally active progestin, ethisterone (pregneninolone, 17α-ethynyltestosterone), the 17α-ethynyl analog of testosterone, synthesized in 1938 by Hans Herloff Inhoffen, Willy Logemann, Walter Hohlweg and Arthur Serini at Schering AG in Berlin, was marketed in Germany in 1939 as Proluton C and by Schering-Plough in the United States in 1945 as Pranone[4][5][6][7][8]

A more potent orally active progestin, norethisterone (norethindrone, 19-nor-17α-ethynyltestosterone), the 19-nor analog of ethisterone, synthesized in 1951 by Carl Djerassi, Luis E. Miramontes, and George Rosenkranz at Syntex in Mexico City, was marketed by Parke-Davis in the U.S. in 1957 as Norlutin, and was used as the progestin in some of the first oral contraceptives (Ortho-Novum, Norinyl, etc.) in the early 1960s.[5][5][6][7][8][9]

Norethynodrel, an isomer of norethisterone, was synthesized in 1952 by Frank B. Colton at G. D. Searle & Company in Skokie, Illinois and used as the progestin in Enovid, marketed in the U.S. in 1957 and approved as the first oral contraceptive in 1960.[5][6][7][8][10]

Examples

Some examples of progestins that have been used in hormonal contraceptives are norethynodrel (Enovid), norethindrone (many brand names, most notably Ortho-Novum and Ovcon) norgestimate (Ortho Tricyclen, Ortho-Cyclen), norgestrel, levonorgestrel (Alesse, Trivora-28, Plan B, Mirena), medroxyprogesterone (Provera, Depo-Provera), desogestrel, etonogestrel (Implanon), and drospirenone (Yasmin, Yasminelle, YAZ).

Sometimes progestins are classified by generation:

First generation

First (estrane): norethindrone, norethynodrel,[11] norethindrone acetate, ethynodiol diacetate

Second generation

  • Second (gonane): levonorgestrel, norethisterone,[12] norgestrel

Third generation

  • Third (gonane): desogestrel, gestodene, norgestimate, drospirenone[12]

Fourth generation

  • Fourth: dienogest, drospirenone, nestorone, nomegestrol acetate and trimegestone[13]

Tanaproget is a non-steroidal progestin.

Methods of progestin-based contraception

It has been found that the most effective method of contraception is with a combination of estrogen and progestin. This can be done in a monophasic, biphasic, or triphasic manner. In the monophasic method, both an estrogen and a progestin are administered for 20 or 21 days and stopped for a 7- or 8-day period that includes the 5-day menstrual period. Sometimes, a 28-day regimen that includes 6 or 7 inert tablets is used. Newer biphasic and triphasic methods are now used to more closely simulate the normal menstrual cycle. Yet another method is to administer a small dose of progestin only (no estrogen) in order to decrease certain risks associated with administering estrogen, but a major side-effect is irregular bleeding usually observed during the first 18 months of such therapy.

References

  1. ↑ Merriam-Webster's medical Dictionary > progestin Retrieved on Feb 13, 2010
  2. ↑ MedicineNet > progestin definition Last Editorial Review: 8/9/2003
  3. ↑ Loose, Davis S.; Stancel, George M. (2006). "Estrogens and Progestins", in Brunton, Laurence L.; Lazo, John S.; Parker, Keith L. (eds.): Goodman & Gilman's The Pharmacological Basis of Therapeutics, 11th, New York: McGraw-Hill, 1541–71. ISBN 0-07-142280-3. 
  4. ↑ Inhoffen HH, Logemann W, Hohlweg W, Serini A (May 4, 1938). "Untersuchungen in der Sexualhormon-Reihe (Investigations in the sex hormone series)". Chemische Berichte 71 (5): 1024–32. 
  5. ↑ 5.0 5.1 5.2 5.3 Maisel, Albert Q. (1965). The Hormone Quest. New York: Random House. OCLC 543168. 
  6. ↑ 6.0 6.1 6.2 Petrow V (1970). "The contraceptive progestagens". Chem Rev 70 (6): 713–26. doi:10.1021/cr60268a004. PMID 4098492. 
  7. ↑ 7.0 7.1 7.2 Sneader, Walter (2005). "Hormone analogues", Drug discovery : a history. Hoboken, NJ: John Wiley & Sons, 188–225. ISBN 0-471-89980-1. 
  8. ↑ 8.0 8.1 8.2 Djerassi C (2006). "Chemical birth of the pill". Am J Obstet Gynecol 194 (1): 290–8. doi:10.1016/j.ajog.2005.06.010. PMID 16389046. 
  9. ↑ Djerassi C, Miramontes L, Rosenkranz G, Sondheimer F (1954). "Steroids. LIV. Synthesis of 19-Nor-17α-ethynyltestosterone and 19-Nor-17α-methyltestosterone" (PDF). Journal of the American Chemical Society 76 (16): 4089–91. doi:10.1021/ja01645a009. 
  10. ↑ Colton FB (1992). "Steroids and "the pill": early steroid research at Searle". Steroids 57 (12): 624–30. doi:10.1016/0039-128X(92)90015-2. PMID 1481226. 
  11. ↑ Medscape.com.
  12. ↑ 12.0 12.1 Birth control options for women - Oral Contraception and Combination Hormonal Methods. Retrieved on 2010-04-01.
  13. ↑ Sitruk-Ware R (2004). "New progestogens: a review of their effects in perimenopausal and postmenopausal women". Drugs Aging 21 (13): 865–83. PMID 15493951. 

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