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Levonorgestrel



Levonorgestrel
Systematic (IUPAC) name
13-ethyl-17-ethynyl-17-hydroxy- 1,2,6,7,8,9,10,11,12,13,14,15,16, 17- tetradecahydrocyclopenta[a] phenanthren-3-one
Identifiers
CAS number	797-63-7
ATC code	G03AC03
PubChem	13109
DrugBank	APRD00754
Chemical data
Formula	C₂₁H₂₈O₂
Mol. mass	312.446 g/mol
Pharmacokinetic data
Bioavailability	~100%
Protein binding	55%
Metabolism	Hepatic
Half life	36 ± 13 hours
Excretion	Renal: 45%; Fecal:32%
Therapeutic considerations
Pregnancy cat.	X
Legal status
Routes	Implant; insert (extended-release); oral

Levonorgestrel (or l-norgestrel or D-norgestrel) is a synthetic progestogen used as an active ingredient in some hormonal contraceptives.

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Chemistry

Chemically, it is a hormonally active levorotatory enantiomer of the racemic mixture norgestrel. It is a gonane progestin derived from 19-nortestosterone.^[1]

Its in vitro relative binding affinities at human steroid hormone receptors are: 323% that of progesterone at the progesterone receptor, 58% that of testosterone at the androgen receptor, 17% that of aldosterone at the mineralocorticoid receptor, 7.5% that of cortisol at the glucocorticoid receptor, and <0.02% that of estradiol at the estrogen receptor.^[2]

Usage

Main article: birth control

Oral contraceptives

At low doses, levonorgestrel is used in monophasic and triphasic formulations of combined oral contraceptive pills, with available monophasic doses ranging from 100-250 µg, and triphasic doses of 50 µg/75 µg/125 µg.

At very low daily dose of 30 µg, levonorgestrel is used in some progestogen only pill formulations.

Emergency contraception

Levonorgestrel is used in emergency contraceptive pills (ECPs), both in a combined Yuzpe regimen which includes estrogen, and as a levonorgestrel-only method. The levonorgestrel-only method uses levonorgestrel 1500 μg (as a single dose or as two 750 μg doses 12 hours apart) taken within 3 days of unprotected sex. There are many brand names of levonorgestrel-only ECPs, including: Plan B, Levonelle, NorLevo, Postinor-2, and 72-HOURS.^[3]

IUD

Levonorgestrel is the active ingredient in Mirena.

Contraceptive implants

Levonorgestrel is the active ingredient in Norplant and Jadelle.

References

^ Edgren RA, Stanczyk FZ (1999). "Nomenclature of the gonane progestins". Contraception 60 (6): 313. PMID 10715364.
^ Sitruk-Ware R (2006). "New progestagens for contraceptive use". Hum Reprod Update 12 (2): 169-78. PMID 16291771.
^ Trussell, James; Cleland, Kelly (2007-04-10). Emergency Contraceptive Pills Worldwide. Princeton University. Retrieved on 2007-05-28.

v • d • e Sex hormones and related agents (primarily G03, also L02, H01C) - human endogenous in CAPS
Progestogens: (receptor)	PROGESTERONE, Desogestrel, Drospirenone, Dydrogesterone, Ethisterone, Etonogestrel, Ethynodiol diacetate, Gestodene, Gestonorone, Levonorgestrel, Lynestrenol, Medroxyprogesterone, Megestrol, Norelgestromin, Norethisterone, Norethynodrel, Norgestimate, Norgestrel, Norgestrienone, Tibolone Selective progesterone receptor modulator: Asoprisnil, CDB-4124 Antiprogestogen: Mifepristone
Androgens: (receptor)	TESTOSTERONE, Androstanolone, Fluoxymesterone, Mesterolone, Methyltestosterone, (see also anabolic steroids) Antiandrogens: Bicalutamide, Cyproterone, Flutamide, Nilutamide, Spironolactone
Estrogens: (receptor)	ESTRADIOL, ESTRIOL, ESTRONE, Chlorotrianisene, Dienestrol, Diethylstilbestrol, Ethinylestradiol, Fosfestrol, Mestranol, Polyestradiol phosphate Selective estrogen receptor modulator: Bazedoxifene, Clomifene, Fulvestrant, Lasofoxifene, Raloxifene, Tamoxifen, Toremifene Aromatase inhibitor: Aminogluthetimide, Anastrozole, Exemestane, Formestane, Letrozole, Vorozole
Gonadotropins: (FSHR/LHCGR)	ovulation stim.: Clomifene, Urofollitropin Antigonadotropins: Danazol, Gestrinone
GnRH: (receptor)	agonist: Buserelin, Goserelin, Histrelin, Leuprorelin, Nafarelin, Triptorelin antagonist: Abarelix, Cetrorelix, Ganirelix

Categories: Hormonal contraception | Progestagens

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Levonorgestrel". A list of authors is available in Wikipedia.