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Levonorgestrel

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Last Updated: 03 January 2021

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General | Latest Info

Levonorgestrel

Chemical and physical data
3D model ( JSmol )Interactive image
FormulaC 21 H 28 O 2
Melting point235 to 237 C (455 to 459 F)
Molar mass312.453 gmol 1
Clinical data
AHFS / Drugs.comMonograph
ATC codeG03AC03 ( WHO ) G03AD01 ( WHO )
Drug classProgestogen (medication) ; Progestin
MedlinePlusa610021
Other namesLNG; d-Norgestrel; d(-)-Norgestrel; D -Norgestrel; WY-5104; SH-90999; NSC-744007; 18-Methylnorethisterone; 17-Ethynyl-18-methyl-19-nortestosterone; 17-Ethynyl-18-methylestr-4-en-17-ol-3-one; 13-Ethyl-17-hydroxy-18,19-dinorpregn-4-en-20-yn-3-one
Pregnancy categoryAU : B3 , Contraindicated
Routes of administrationBy mouth , transdermal patch , intrauterine device , subcutaneous implant
Trade namesPlan B, others
Identifiers
CAS Number797-63-7 Y
ChEBICHEBI:6443 Y
ChEMBLChEMBL1389 Y
ChemSpider12560 Y
CompTox Dashboard ( EPA )DTXSID3036496
DrugBankDB00367 Y
ECHA InfoCard100.011.227
IUPHAR/BPS2881
KEGGD00950 Y
PubChem CID13109
UNII5W7SIA7YZW
Legal status
Legal statusUS : -only / OTC, In general: (Prescription only)
Pharmacokinetic data
Bioavailability95% (range 85-100%)
Elimination half-life24-32 hours
ExcretionUrine : 20-67% Feces : 21-34%
MetabolismLiver ( reduction , hydroxylation , conjugation )
Metabolites5-Dihydro- LNG
Protein binding98% (50% to albumin , 48% to SHBG )
SMILES CC 12CC 3 ( 1CC 2(C#C)O)CCC4=CC(=O)CC 34
(verify)

Levonorgestrel is used to prevent pregnancy after unprotected sexual intercourse. Levonorgestrel should not be used to prevent pregnancy on a regular basis. This medication is to be used as an emergency contraceptive or backup in case regular birth control fails or is used incorrectly. Levonorgestrel is in a class of medications called progestins. It works by preventing release of egg from the ovary or preventing fertilization of egg by sperm. It also may work by changing the lining of the uterus to prevent development of pregnancy. Levonorgestrel may prevent pregnancy, but it will not prevent the spread of human immunodeficiency virus and other sexually transmitted diseases. Levonorgestrel comes as a tablet to take by mouth. If you are taking levonorgestrel as single tablet product, take one tablet as soon as possible within 72 hours after unprotected sexual intercourse. If you are taking levonorgestrel as two tablet product, take one tablet as soon as possible within 72 hours after unprotected sexual intercourse and take the second dose 12 hours later. Levonorgestrel works best if it is taken as soon as possible after unprotected sexual intercourse. Follow directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take levonorgestrel exactly as direct. If you vomit less than 2 hours after you take dose of levonorgestrel, call your doctor. You may need to take another dose of this medication. Because you can become pregnant soon after treatment with levonorgestrel, you should continue using your regular method of birth control or begin using regular birth control immediately.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

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* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Medical uses

This combination hormone medication is used to prevent pregnancy. It contains 2 hormones: levonorgestrel and ethinyl estradiol. It works mainly by preventing the release of eggs during your menstrual cycle. It also makes vaginal fluid thicker to help prevent sperm from reaching egg and changes the lining of the uterus to prevent attachment of fertilized egg. Besides preventing pregnancy, birth control pills may make your periods more regular, decrease blood loss and painful periods, decrease your risk of ovarian cysts, and also treat acne. Using this medication does not protect you or your partner against sexually transmitted diseases.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Contraindications

Levonorgestrel can be taken a single dose of 1. 5 mg or two 0. 75-mg dose take at same time or 12 hours apart within 72 hours of unprotected intercourse. 14 15 There is decreased effectiveness as time passes after unprotected intercourse. Effectiveness ranges from 58 % to 79 %. 15 16 expect pregnancy rate of 4 % decrease to less than 2 % after use of Levonorgestrel. The number needed to treat to prevent One pregnancy is 43. 10 Single-dose Levonorgestrel has similar effectiveness as split-dose regimen. 12 17 Single and split dosing were found to be equally effective at preventing unintended pregnancy, even with additional acts of unprotected intercourse. 12 Levonorgestrel works by interfering with luteinizing hormone peak during the cycle. 18 19 When Levonorgestrel was given before peak, it was effective at preventing ovulation, but it do not prevent pregnancy if ovulation and fertilization had already occur. 18 20 Levonorgestrel Use may cause earlier onset of menstrual bleeding, headache, fatigue, dizziness, back pain, and dysmenorrhea.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Interactions

Emergency contraception with progestogen only is better tolerated and more effective than combine oestrogen-progestogen regimen. 1 Furthermore, treatment with progestogens only may be preferable to Yuzpe regimen in women with known thrombophilic defect or history of thromboembolic events. For women receiving warfarin, drug information cites either no interaction between progestogens and warfarin 2 or reduction in anticoagulant effect. 3 We describe the enhanced anticoagulant effect of warfarin after giving woman levonorgestrel for emergency contraception. A 35 year old woman with familial type 1 antithrombin deficiency and a history of extensive deep venous thrombosis and pulmonary thromboembolism, attends clinic after an episode of unprotected intercourse. She was receiving warfarin 7 mg daily for anticoagulation but no other drugs. Her international normalised ratio was 2. 1, which was within therapeutic range. She requested emergency contraception. After counselling, she declined insertion of intrauterine contraceptive device, preferring progestogen only regimen. Her international normalised ratio was rechecked three days later and was reported as 8. 1 She was advised to discontinue warfarin treatment for two days, at which point her international normalised ratio was 2. 5, and then to restart it at a dose of 5 mg once daily. No haemorrhagic problems occur. One possible explanation for this enhanced anticoagulant effect is displacement of warfarin by levonorgestrel from F1S binding site of human 1-acid glycoprotein, main transport protein for drugs in plasma. 4 variant of the F1S binding site comprises part of the F1S / phenotype of 1-acid glycoprotein, which is encountered in 50 % of the population. Thus, women receiving warfarin treatment may be at risk of interaction between warfarin and levonorgestrel if they are prescribed progestogen only regimen because of its apparent safety. The manufacturer of levonorgestrel has not received any reports describing such interaction with warfarin. This potential interaction requires prompt investigation, particularly in light of recommendations that emergency contraception be made available over counter. 5 If patients are fully anticoagulated with warfarin, conventional Yuzpe regimen may be effective without being associated with any increased risk of venous thromboembolism.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

History

Norgestrel, racemic mixture containing Levonorgestrel and dextronorgestrel, was discovered by Hughes and colleagues at Wyeth in 1963 via structural modification of norethisterone. It was the first progestogen to be manufactured via total chemical synthesis. Norgestrel was introduced for medical use as a combined birth control pill with ethinylestradiol under the brand name Eugynon in Germany in 1966 and under the brand name Ovral in the United States in 1968, and as a progestogen-only pill under the brand name Ovrette in the United States in 1973. Following its discovery, norgestrel had been licensed by Wyeth to Schering AG, which separated the racemic mixture into its two optical isomers and identified Levonorgestrel as active component of the mixture. Levonorgestrel was first studied in humans in 1970, and was introduced for medical use in Germany as a combined birth control pill with ethinylestradiol under the brand name Neogynon in August 1970. More widely used formulation, containing lower doses of ethinylestradiol and Levonorgestrel, was introduced under the brand name Microgynon in 1973. In addition to combined formulations, Levonorgestrel was introduced as a progestogen-only pill under the brand names Microlut in 1972 and Microval in 1974. Many other formulations and brand names of Levonorgestrel-containing birth control pills have also been market. Levonorgestrel, taken alone at single high dose, was first evaluated as a form of emergency contraception in 1973. It was the second progestin to be evaluated for such purposes, following the study of quingestanol acetate in 1970. In 1974, Yuzpe regimen, which consisted of high doses of combined birth control pill containing ethinylestradiol and norgestrel, was described as a method of emergency contraception by. Albert Yuzpe and colleagues, and saw widespread interest. Levonorgestrel-only emergency contraception was introduced under the brand name Postinor by 1978. Ho and Kwan published the first study comparing Levonorgestrel only and Yuzpe regimen as methods of emergency contraception in 1993 and found that they had similar effectiveness but that Levonorgestrel alone was better-tolerate. In relation to this, Yuzpe regimen has largely been replaced as a method of emergency contraception by levonorgrestrel-only preparations. Levonorgestrel-only emergency contraception was approved in the United States under the brand name Plan B in 1999, and has also been marketed widely elsewhere throughout the world under other brand names such as Levonelle and NorLevo in addition to Postinor. In 2013, Food and Drug Administration approved Plan B One-Step for sale over-counter in the United States without prescription or age restriction. Levonorgestrel has also been introduced for use as a progestogen-only intrauterine device under brand names Mirena and Skyla among others, as a progestogen-only birth control implant under brand names Norplant and Jadelle, as a combined oral tablet with estradiol valerate for menopausal hormone therapy under the brand name Klimonorm, and as a combined transdermal patch with estradiol for menopausal hormone therapy under brand name Climara Pro.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Society and culture

A number of studies provide strong direct evidence that LNG ECPs prevent or delay ovulation. If taken before ovulation, LNG ECPs inhibit pre-ovulatory luteinizing hormone surge, impeding follicular development and maturation and / or release of the egg itself. 1 2345678 This is the primary mechanism of action for LNG ECPs. Two studies have estimated the effectiveness of LNG ECPs by confirming cycle day by hormonal analysis. In these studies, no pregnancies occur in women who take ECPs before ovulation, while pregnancies occur only in women who take ECPs on or after the day of ovulation, providing evidence that ECPs were unable to prevent implantation. 9 10 number of studies have evaluated whether ECPs produce changes in histological and biochemical characteristics of endometrium. Most studies show that LNG ECPs have no such effect on endometrium, indicating that they have no mechanism to prevent implantation. 1 211 12 13 One of these studies found that following administration of double standard dose of LNG, there are only minor or no alterations in endometrial receptivity. 12 One study found single altered endometrial parameter only when LNG was administered prior to LH surge, at time when ECPs inhibit ovulation. 14 One study shows that levonorgestrel does not prevent attachment of human embryos to simulate the endometrial environment. 15 Animal studies demonstrate that LNG ECPs do not prevent implantation of fertilized eggs in the endometrium. 16 17 contradictory results exist regarding whether LNG take post-coitally and in doses used for EC affects sperm function. Early studies suggest that LNG ECPs interfere with sperm motility by thickening cervical mucus. 18 19 However, two in vitro studies find that LNG in doses used for EC has no direct effect on sperm function. 20 21 Recent in vivo studies find no effect of LNG on the number of viable sperm found in female genital tract 24-28 hours after taking LNG. 22 Interference in sperm migration is also a possible explanation in women who take LNG ECP before ovulation, but had document follicle rupture in the following 5 days, yet do not get pregnant. 9 New evidence about interaction between sperm and progesterone suggests a possible deleterious effect of high concentrations of progestin LNG on sperm function, that may cause sperm to be hyperactive in the absence of egg or interfere with directionality of sperm movement. 23 24 25 26 27 give these results, This mechanism of action is still uncertain and warrants further studies. Two studies of women who become pregnant in cycles when they take LNG ECPs found no difference between pregnancy outcomes of women who had taken LNG ECPs and those who had not. Variables include miscarriage, birth weight, malformations, and sex ratio, indicating that LNG ECPs have no effect on establishing pregnancy even at very early stages. 28 29 emergency contraception is not the same as early medical abortion. LNG ECPs are effective only in the first few days following intercourse before ovum is released from the ovary and before sperm fertilizes ovum.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Sources

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

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