Levonorgestrel: Difference between revisions
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Revision as of 14:00, 22 June 2007
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| Clinical data | |
|---|---|
| Pregnancy category |
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| Routes of administration | Implant; insert (extended-release); oral |
| ATC code | |
| Pharmacokinetic data | |
| Bioavailability | ~100% |
| Protein binding | 55% |
| Metabolism | Hepatic |
| Elimination half-life | 36 ± 13 hours |
| Excretion | Renal: 45%; Fecal:32% |
| Identifiers | |
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| CAS Number | |
| PubChem CID | |
| DrugBank | |
| CompTox Dashboard (EPA) | |
| ECHA InfoCard | 100.011.227 |
| Chemical and physical data | |
| Formula | C21H28O2 |
| Molar mass | 312.446 g/mol g·mol−1 |
Levonorgestrel (or l-norgestrel or D-norgestrel) is a synthetic progestogen used as an active ingredient in some hormonal contraceptives.
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
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 contraception pills, both in a combined regimen which includes estrogen, and as a levonorgestrel-only method. For the latter, a single dose of 1500 μg within 3 days is almost 100% effective. There are many brand names of levonorgestrel-only emergency contraception pills, including: Plan B, Levonelle, NorLevo, Postinor-2, and many others.[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 2007-05-28.
{{cite web}}: CS1 maint: multiple names: authors list (link)
External links
- Levonelle manufacturer's product information from Schering
- Monograph for levonorgestrel - Uk Medicines Information
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