Levonorgestrel
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| 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 | |
| Clinical data | |
| Trade names | Norplant |
| MedlinePlus | a610021 |
| Pregnancy cat. | X |
| Legal status | ℞ Prescription only |
| Routes | Implant; insert (extended-release); oral |
| Pharmacokinetic data | |
| Bioavailability | ~100% |
| Protein binding | 55% |
| Metabolism | Hepatic via CYP3A4 |
| Half-life | 36 ± 13 hours |
| Excretion | Renal: 45%; Fecal:32% |
| Identifiers | |
| CAS number | 797-63-7  |
| ATC code | G03AC03 G03AD01 |
| PubChem | CID 13109 |
| DrugBank | APRD00754 |
| ChemSpider | 12560 |
| UNII | 5W7SIA7YZW |
| KEGG | D00950 |
| ChEBI | CHEBI:6443 |
| ChEMBL | CHEMBL1389 |
| Chemical data | |
| Formula | C21H28O2 |
| Mol. mass | 312.446 g/mol |
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Levonorgestrel (or l-norgestrel or D-norgestrel) (Plan B, Next Choice, and others[1]) is a second generation synthetic progestogen used as an active ingredient in some hormonal contraceptives.
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[edit] Chemistry
Levonorgestrel (levo=left) is one form of a hormone that exists in two mirror image left and right forms.
Chemically, it is a hormonally active levorotatory enantiomer of the racemic mixture norgestrel. It is a gonane progestin derived from 19-nortestosterone.[2]
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.[3]
If taken together with drugs that induce the CYP3A4 cytochrome liver enzyme, the levonorgestrel will be metabolized faster and have lower efficacy, and a larger dose will be needed.[citation needed]
[edit] Usage
[edit] Oral contraception
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.
[edit] 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 1.5 mg (as a single dose or as two .75 mg doses 12 hours apart) taken within 3 days of unprotected sex, with one study indicating that beginning as late as 120 hours (5 days) after intercourse could be effective. There are many brand names of levonorgestrel-only ECPs, including: Escapelle, Plan B, Levonelle, NorLevo, Postinor-2, i-pill, "Next Choice" and 72-HOURS.[4]
[edit] Intrauterine system
Levonorgestrel is the active ingredient in the Mirena intrauterine system.
[edit] Contraceptive implants
Levonorgestrel is the active ingredient in Norplant and Jadelle.
[edit] Side effects
Possible side effects of levonorgestrel include nausea, vomiting, stomach pain, dizziness, breast tenderness, tiredness and weakness, headache, menstrual changes, and diarrhea.[5]
It decreases total and free testosterone, androstenedione, dehydroepiandrosterone sulfate (DHEAS), dihydrotestosterone (DHT) and sex hormone–binding globulin (SHBG), but has no effect on sexual function or markers of androgen bioactivity.[6]
[edit] References
- ^ http://ec.princeton.edu/questions/dose.html#dose
- ^ Edgren RA, Stanczyk FZ (1999). "Nomenclature of the gonane progestins". Contraception 60 (6): 313. doi:10.1016/S0010-7824(99)00101-8. PMID 10715364.
- ^ Sitruk-Ware R (2006). "New progestagens for contraceptive use". Hum Reprod Update 12 (2): 169–78. doi:10.1093/humupd/dmi046. PMID 16291771.
- ^ Trussell, James; Cleland, Kelly (2007-04-10). "Emergency Contraceptive Pills Worldwide". Princeton University. http://ec.princeton.edu/questions/dedicated.html. Retrieved 2007-05-28.
- ^ MedicineNet.com > LEVONORGESTREL - ORAL (lee-voh-nor-JEST-rell) Retrieved on April 3, 2010
- ^ Kovalevsky G, Ballagh SA, Stanczyk FZ, Lee J, Cooper J, Archer DF (April 2010). "Levonorgestrel effects on serum androgens, sex hormone-binding globulin levels, hair shaft diameter, and sexual function". Fertil. Steril. 93 (6): 1997–2003. doi:10.1016/j.fertnstert.2008.12.095. PMID 19394598.
[edit] External links
- Levonelle manufacturer's product information from Schering
- Monograph for levonorgestrel - Uk Medicines Information
- U.S. National Library of Medicine: Drug Information Portal - Levonorgestrel
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