Editing Levonorgestrel (section)

===Available forms===
As a type of emergency contraception, levonorgestrel is used after unprotected intercourse to reduce the risk of pregnancy.<ref name="Emergency Contraception - ACOG">{{Cite web|url=https://www.acog.org/Clinical-Guidance-and-Publications/Practice-Bulletins/Committee-on-Practice-Bulletins-Gynecology/Emergency-Contraception?IsMobileSet=false|title=Emergency Contraception - ACOG|website=www.acog.org|access-date=1 June 2019|archive-date=9 October 2019|archive-url=https://web.archive.org/web/20191009072551/https://www.acog.org/Clinical-Guidance-and-Publications/Practice-Bulletins/Committee-on-Practice-Bulletins-Gynecology/Emergency-Contraception?IsMobileSet=false|url-status=live}}</ref> However, it can serve different hormonal purposes in its different methods of delivery. It is available for use in a variety of forms:

====By mouth====
Levonorgestrel can be taken by mouth as a form of emergency birth control. The typical dosage is either 1.5&nbsp;mg taken once or 0.75&nbsp;mg taken 12–24 hours apart.<ref name=":0">{{cite journal | vauthors = Hansen LB, Saseen JJ, Teal SB | title = Levonorgestrel-only dosing strategies for emergency contraception | journal = Pharmacotherapy | volume = 27 | issue = 2 | pages = 278–84 | date = February 2007 | pmid = 17253917 | doi = 10.1592/phco.27.2.278 | s2cid = 24229915 }}</ref> The effectiveness in both methods is similar.<ref name=":0" /> The most widely used form of oral emergency contraception is the [[Progestogen-only pill|progestin-only pill]], which contains a 1.5&nbsp;mg dosage of levonorgestrel.<ref name="Emergency Contraception - ACOG"/> Levonorgestrel-only emergency contraceptive pills are reported to have an 89% effectiveness rate if taken within the recommended 72 hours after sex.<ref name=":1">{{cite journal | vauthors = Shohel M, Rahman MM, Zaman A, Uddin MM, Al-Amin MM, Reza HM | title = A systematic review of effectiveness and safety of different regimens of levonorgestrel oral tablets for emergency contraception | journal = BMC Women's Health | volume = 14 | pages = 54 | date = April 2014 | pmid = 24708837 | pmc = 3977662 | doi = 10.1186/1472-6874-14-54 | doi-access = free }}</ref> The efficacy of the drug decreases by 50% for each 12-hour delay in taking the dose after the emergency contraceptive regimen has been started.<ref name=":1" />

====Skin patch====
{{See also|Estradiol/levonorgestrel}}

[[Estradiol/levonorgestrel|Estradiol with levonorgestrel]] in the form of a skin patch is used under the brand name Climara Pro for [[hormone replacement therapy]] in postmenstrual women, treating symptoms such as [[hot flash]]es or [[osteoporosis]].<ref name=":2">{{Cite web|url=https://www.mayoclinic.org/drugs-supplements/estradiol-and-levonorgestrel-transdermal-route/description/drg-20112971|title=Estradiol And Levonorgestrel (Transdermal Route) Description and Brand Names - Mayo Clinic|website=www.mayoclinic.org|access-date=1 June 2019|archive-date=31 May 2019|archive-url=https://web.archive.org/web/20190531172016/https://www.mayoclinic.org/drugs-supplements/estradiol-and-levonorgestrel-transdermal-route/description/drg-20112971|url-status=live}}</ref> The simultaneous delivery of a [[progestogen (medication)|progestogen]] such as levonorgestrel is necessary for the protection of the [[endometrium]].<ref name=":3">{{Cite web|url=https://www.accessdata.fda.gov/drugsatfda_docs/label/2005/021885lbl.pdf|title=Climara Pro® (Estradiol/Levonorgestrel Transdermal System)|website=Food and Drug Administration|access-date=1 June 2019|archive-date=28 February 2021|archive-url=https://web.archive.org/web/20210228161531/https://www.accessdata.fda.gov/drugsatfda_docs/label/2005/021885lbl.pdf|url-status=dead}}</ref><ref>{{cite journal | vauthors = Mueck AO, Römer T | s2cid = 51886877 | title = Choice of progestogen for endometrial protection in combination with transdermal estradiol in menopausal women | journal = Hormone Molecular Biology and Clinical Investigation | volume = 37 | issue = 2 | date = July 2018 | pmid = 30063464 | doi = 10.1515/hmbci-2018-0033 | doi-access = free }}</ref>

====Intrauterine device====
The levonorgestrel intrauterine system (LNG-IUS) is a type of long-term birth control that releases the progestin into the uterine cavity.<ref name=Jeff2005>{{cite journal | vauthors = Jensen JT | s2cid = 43177026 | title = Contraceptive and therapeutic effects of the levonorgestrel intrauterine system: an overview | language = en-US | journal = Obstetrical & Gynecological Survey | volume = 60 | issue = 9 | pages = 604–12 | date = September 2005 | pmid = 16121115 | doi = 10.1097/01.ogx.0000175805.90122.af }}</ref><ref name="Bao Q 2018"/> Levonorgestrel is released at a constant, gradual rate of 0.02&nbsp;mg per day by the polydimethylsiloxane membrane of the device, which renders it effective for up to five years.<ref name=Jeff2005 /> 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&nbsp;ng of levonorgestrel to the inner uterine region while a comparable oral contraceptive delivers only 1.35&nbsp;ng.<ref name=Jeff2005 /> This high level of levonorgestrel impedes the function of the endometrium, making it hostile for sperm transport, fertilization, and implantation of an ovum.<ref name=Jeff2005 />

====Implant====
[[Subcutaneous implant]]s of levonorgestrel have been marketed as [[birth control implant]]s under the brand names Norplant and Jadelle and are available for use in some countries.<ref name="pmid18803473">{{cite journal | vauthors = Benagiano G, Gabelnick H, Farris M | title = Contraceptive devices: subcutaneous delivery systems | journal = Expert Review of Medical Devices | volume = 5 | issue = 5 | pages = 623–637 | date = September 2008 | pmid = 18803473 | doi = 10.1586/17434440.5.5.623 | s2cid = 207201811 }}</ref><ref name="Drugs.com" />