Jump to content

User:Tania.bhatti/sandbox

From Wikipedia, the free encyclopedia
< User:Tania.bhatti

This is an old revision of this page, as edited by Jasminenwee (talk | contribs) at 20:45, 31 May 2019 (→Production). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Levonorgestrel (LNG) is the most frequently used form of emergency contraception (EC) globally.[1] In its oral form, it is commonly taken within 120 hours of unprotected sex, and can be taken as a single dosage of 1.5 mg or as two doses of 0.75 mg taken 12 hours apart, although the former is recommended.[1] Under these conditions, levonorgestrel is estimated to decrease the chances of pregnancy by 57-93%.[1]


Method

Production

Levonorgestrel is produced directly from the compound methoxydienone [2]. Acetylene gas is passed through a saturated solution of potassium hydroxide creating a tetrahydrofuran solution[2]. Methoxydienone is dissolved in acetone then added drop-wise to the tetrahydrofuran solution and stirred to completion of the reaction[2]. Water is added to separate the organic layer that is formed, which is then removed and mixed with hydrochloric acid[2]. When the pH reaches 1, the solution is warmed and the levonorgestrel is obtained[2].

Functionality in the body

Levonorgestrel, a type of progestin, mimics the effects of progesterone by tricking the body into thinking ovulation has already occurred. However, levonorgestrel may bind to and interact differently with progesterone receptors which may result in differing effects.

Levonorgestrel inhibits three main processes in the body: ovulation, fertilization, and implantation.

  • Ovulation: LNG mimics progesterone through a negative feedback loop. Progesterone is naturally produced by the ovaries to inhibit ovulation during pregnancy.
  • Fertilization:
  • Implantation: LNG decreases the endometrial lining over time, causing

Medical uses

Emergency birth control

As part of the medication Plan B, levonorgestrel functions by preventing pregnancy at various points in the fertilization process. Levonorgestrel firstly stops ovulation from occurring, halting the release of an egg from the ovary that could potentially meet a sperm cell after intercourse.[3] If the drug is taken after ovulation has occurred, it can prevent fertilization.[3] If fertilization has already taken place, it can block implantation.[3] If Plan B is successful, each point in this process would effectively halt a pregnancy. However, if implantation occurs successfully, pregnancy may not be avoided.[3]

Available Forms

**Levonorgestrel is available alone in emergency contraceptive pills and progestogen-only pills, in combination with ethinylestradiol in birth control pills, in combination with estradiol valerate in oral tablets for use in menopausal hormone therapy, in combination with estradiol in a transdermal patch for use in menopausal hormone therapy, alone as an intrauterine device for use in hormonal birth control, and alone as a subcutaneous birth control implant.[14][29][30] **

As a type of emergency contraception, levonorgestrel is used after unprotected intercourse to reduce the risk of pregnancy.[4] However, it can serve different hormonal purposes in its different methods of delivery. It is available for use in a variety of forms:

Pill

Levonorgestrel can be taken orally in the form of an emergency contraceptive pill. The typical dosage is either 1.5 mg taken once, as suggested by the American College of Obstetricians and Gynecologists, or 0.75 mg taken 12-24 hours apart, as approved by the FDA.[5] The effectiveness of the drug is not affected by choosing one regimen over the other.[5] The most widely used form of oral emergency contraception is the progestin-only pill, which contains a 1.5 mg dosage of levonorgestrel.[4]

Patch

Levonorgestrel in the form of a patch is generally used for hormone replacement therapy in post-menstrual women, treating symptoms such as osteoporosis or hot flashes.[6] It is commonly paired with the hormone estradiol in a estradiol/levonorgestrel transdermal system.[6] These patches typically release about 0.045 mg of estradiol and 0.015 mg of levonorgestrel in a 24-hour period.[7] While studies have shown that increasing the proportion of levonorgestrel does not affect the amount or advantages of estradiol release, the simultaneous delivery of a progestogen such as levonorgestrel is necessary for the protection of the endometrium.[7][8][9] The estradiol/levonorgestrel transdermal patch has been found to be effective in combating symptoms of menopause, namely decreasing vasomotor symptoms and increasing bone mineral density.[8][10]

Intrauterine Device

The levonorgestrel intrauterine system (LNG-IUS) is a type of long-term birth control that releases the progestin into the uterine cavity.[11][12] Levonorgestrel is released at a constant, gradual rate of 0.02 mg per day by the polydimethylsiloxane membrane of the device, which renders it effective for up to 5 years.[11] The mechanism of LNG-IUD is primarily preconceptual—it inhibits sperm transport, uterine lining development, and implantation.[13] Because it is inserted directly into the uterus, levonorgestrel is present in the endometrium in much higher concentrations that would result from a LNG-containing oral pill; the LNG-IUS delivers 391 ng of levonorgestrel to the inner uterine region while a comparable oral contraceptive delivers only 1.35 ng.[11] This high level of levonorgestrel impedes the function of the endometrium, making it hostile for sperm transport, fertilization, and implantation of an ovum.[11] The LNG-IUS also triggers the activity of glycodelin A (GdA), a glycoprotein found in the uterus that has natural contraceptive behavior, as it interferes with the bonding of the egg and sperm.[13]

Implant

Levonorgestrel is used in silastic implants as a long-term contraceptive regimen. It releases about 0.03 mg of levonorgestrel at a constant rate.[2] Users of this type of implant report irregularities and aggravated symptoms of their menstrual cycle more then users of the levonorgestrel oral pills, however, these effects are mostly characteristic of the first year of implant use.[2][14] The LNG implant is notably effective due to its prolonged use by users

Chemistry

See also: List of progestogens, List of androgens/anabolic steroids, and Norgestrel

** Levonorgestrel, also known as 17α-ethynyl-18-methyl-19-nortestosterone or as 17α-ethynyl-18-methylestr-4-en-17β-ol-3-one, is a syntheticestrane steroid and a derivative of testosterone.[42][43] It is the C13β or levorotatory stereoisomer and enantiopure form of norgestrel, the C13α or dextrorotatory isomer being inactive.[44][45] Levonorgestrel is more specifically a derivative of norethisterone (17α-ethynyl-19-nortestosterone) and is the parent compound of the gonane (18-methylestrane) subgroup of the 19-nortestosterone family of progestins.[46] Levonorgestrel acetate and levonorgestrel butanoate are C17β esters of levonorgestrel.[47][48] It has a molecular weight of 312.45 g/mol and LogP=3.8. **

Reaction Mechanism

  1. ^ a b c "ScienceDirect". www.sciencedirect.com. Retrieved 2019-05-13.
  2. ^ a b c d e f g Wong, Fung Fuh; et al. "Synthesis process of levonorgestrel by methoxydienone". Google Patents (in Chinese). Retrieved 15 May 2019. Cite error: The named reference ":9" was defined multiple times with different content (see the help page).
  3. ^ a b c d Research, Center for Drug Evaluation and (2018-11-03). "FDA's Decision Regarding Plan B: Questions and Answers". FDA.
  4. ^ a b "Emergency Contraception - ACOG". www.acog.org. Retrieved 2019-05-13.
  5. ^ a b Hansen, Laura B.; Saseen, Joseph J.; Teal, Stephanie B. (2007-2). "Levonorgestrel-only dosing strategies for emergency contraception". Pharmacotherapy. 27 (2): 278–284. doi:10.1592/phco.27.2.278. ISSN 0277-0008. PMID 17253917. {{cite journal}}: Check date values in: |date= (help)
  6. ^ a b "Estradiol And Levonorgestrel (Transdermal Route) Description and Brand Names - Mayo Clinic". www.mayoclinic.org. Retrieved 2019-05-31.
  7. ^ a b "Climara Pro® (Estradiol/Levonorgestrel Transdermal System)" (PDF). Food and Drug Administration. {{cite web}}: Cite has empty unknown parameter: |dead-url= (help)
  8. ^ a b von Holst, Thomas; Salbach, Birgitt (2002-03-25). "Efficacy of a new 7-day transdermal sequential estradiol/levonorgestrel patch in women". Maturitas. 41 (3): 231–242. doi:10.1016/S0378-5122(01)00297-3. ISSN 0378-5122.
  9. ^ Mueck, Alfred O.; Römer, Thomas (2018-07-31). "Choice of progestogen for endometrial protection in combination with transdermal estradiol in menopausal women". Hormone Molecular Biology and Clinical Investigation. 37 (2). doi:10.1515/hmbci-2018-0033. ISSN 1868-1891. PMID 30063464.
  10. ^ Warming, L.; Ravn, P.; Christiansen, C. (2005-02-14). "Levonorgestrel and 17β-estradiol given transdermally for the prevention of postmenopausal osteoporosis". Maturitas. 50 (2): 78–85. doi:10.1016/j.maturitas.2004.03.016. ISSN 0378-5122.
  11. ^ a b c d Jensen, Jeffrey T. (2005-9). "Contraceptive and Therapeutic Effects of the Levonorgestrel Intrauterine System: An Overview". Obstetrical & Gynecological Survey. 60 (9): 604. doi:10.1097/01.ogx.0000175805.90122.af. ISSN 0029-7828. {{cite journal}}: Check date values in: |date= (help)
  12. ^ Bao, Quanying; Gu, Bing; Price, Claire F.; Zou, Yuan; Wang, Yan; Kozak, Darby; Choi, Stephanie; Burgess, Diane J. (2018-10-25). "Manufacturing and characterization of long-acting levonorgestrel intrauterine systems". International Journal of Pharmaceutics. 550 (1): 447–454. doi:10.1016/j.ijpharm.2018.09.004. ISSN 0378-5173.
  13. ^ a b Seppälä, M.; Affandi, B.; Koistinen, R.; Koistinen, H.; Mandelin, E. (1997-12-01). "Levonorgestrel-releasing intrauterine device-wearing women express contraceptive glycodelin A in endometrium during midcycle: another contraceptive mechanism?". Human Reproduction. 12 (12): 2671–2675. doi:10.1093/humrep/12.12.2671. ISSN 0268-1161.
  14. ^ Berenson, Abbey B.; Wiemann, Constance M. (1995-04-01). "Use of levonorgestrel implants versus oral contraceptives in adolescence: A case-control study". American Journal of Obstetrics and Gynecology. 172 (4, Part 1): 1128–1137. doi:10.1016/0002-9378(95)91471-4. ISSN 0002-9378.
Retrieved from "https://en.wikipedia.org/enwiki/w/index.php?title=User:Tania.bhatti/sandbox&oldid=899713707"