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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.

Additional recommended knowledge

Contents

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

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