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Class: Contraceptives
ATC Class: G03FA10
VA Class: HS200
CAS Number: 54048-10-1
Brands: Implanon, Micronor, Mirena, Next Choice, Nor-QD, Plan B One-Step


Contraceptives containing synthetic progestinic steroids.106 117 119 120 125 a

Uses for Progestins


Prevention of conception in women.117 119 120 125 a

Predominantly used by women who are breastfeeding and in those who do not tolerate estrogens or in whom estrogens are contraindicated.b

Levonorgestrel-releasing intrauterine system (Mirena): Intended for women who have had ≥1 child; are in a stable, mutually monogamous relationship; have no history of pelvic inflammatory disease (PID); and have no history of ectopic pregnancy or any condition that would predispose to ectopic pregnancy.117

Postcoital (Emergency) Contraception

Prevention of conception after unprotected intercourse (including known or suspected contraceptive failure) as an emergency contraceptive (“morning-after” pills). 101 102 106 126 127 128 129 130 132 Postcoital (emergency) contraceptive regimens are not as effective as most other forms of long-term contraception and should not be used as routine forms of contraception.106 126 127 132

An emergency contraceptive regimen employing a progestin alone (levonorgestrel) appears to be more effective and better tolerated than a common estrogen-progestin emergency contraceptive (“Yuzpe”) regimen when the regimens are initiated within 72 hours of unprotected intercourse, and therefore, generally is preferred when readily available.101 102 126 127 128 129

Progestins Dosage and Administration


Administer norethindrone orally.119 120

Administer levonorgestrel orally or as an intrauterine system.106 117 132

Administer etonogestrel implant by sub-Q insertion.125

Oral Administration


Take as near as possible to the same time each day (i.e., at regular 24-hour intervals) and continue daily without interruption to ensure maximum contraceptive efficacy.119 120

If vomiting occurs soon after a dose, use a back-up method of contraception (e.g., condoms, foam, sponges) for 48 hours.119 120

Available in a mnemonic dispensing package designed to aid the user in complying with the prescribed dosing regimen.119 120

Postcoital (Emergency) Contraception

Plan B One-Step, Next Choice: Administer as soon as possible but preferably within 72 hours following unprotected sex.106 132

Most data support administration of the first dose up to 120 hours after unprotected intercourse if necessary,126 127 128 but efficacy decreases as initiation of contraception becomes more remote from unprotected intercourse.101 102 103 126 127 128

May be used at any time during the menstrual cycle.106 132 Efficacy not established if administered >120 hours after unprotected sex.126 127

Plan B One-Step: If vomiting occurs within 2 hours after administration, consider repeating the dose.132

Next Choice: If vomiting occurs within 1 hour after administration, the woman should contact her healthcare provider to discuss repeating the dose.106

Food not effective in reducing adverse GI effects (i.e., nausea).126 127

Sub-Q Administration

Insert etonogestrel implant (Implanon) subdermally in the inner aspect of the upper arm about 6–8 cm above the elbow crease.125 Consult manufacturer’s labeling for proper method of administration and associated precautions.125

Intrauterine Administration

Insert levonorgestrel-releasing intrauterine system (Mirena) into the uterine cavity under strict aseptic conditions.117 (See Intrauterine Device Considerations under Cautions.) Consult manufacturer’s labeling for proper methods of inserting and removing the intrauterine system and for associated precautions.117


When switching contraceptive methods, initiate new therapy in a manner that ensures continuous contraceptive coverage based on the mechanism of action of both methods.117 119 120 125



Norethindrone: 0.35 mg daily.119 120 Take 1 tablet each day and continue daily without interruption.119 120 Start on the first day of the menstrual cycle.119 120 If the first dose is taken on another day, use back-up method of contraception (e.g., condom, spermicide) for each sexual encounter for the next 48 hours.119 120

Women switching from estrogen-progestin oral contraceptives: Start norethindrone on the day after the last hormonally active tablet.119 120

Women may start using norethindrone tablets on the next day after a miscarriage or an abortion.119 120

Women whose infants are only partially breast-fed may begin norethindrone 3 weeks after delivery.119 120 Women who are exclusively breast-feeding their infants may begin 6 weeks after delivery.119 120

When a dose is taken >3 hours late or if one or more consecutive doses are missed, take the missed dose as soon as remembered, then resume regular schedule; use a back-up method of contraception (e.g., condom, spermicide) for 48 hours.119 120 If unsure of what drug regimen to take as a result of missed tablets, use a back-up method of contraception for each sexual encounter and take one tablet daily until clinician contacted.119 120


Etonogestrel contraceptive implant (Implanon): One 68-mg implant every 3 years.125

To initiate therapy in women who did not use hormonal contraception in the preceding month, insert the contraceptive implant on or before day 5 of the cycle; a back-up method of contraception is not needed.125

Women switching from estrogen-progestin oral contraceptives, contraceptive transdermal system, or vaginal contraceptive ring: Insert the contraceptive implant within 7 days of the last hormonally active tablet, removal of a transdermal patch, or removal of the vaginal ring; a back-up method of contraception is not needed.125

Women switching from progestin-only oral contraceptives: Insert the contraceptive implant on any day of the month (without skipping any day between receiving the last progestin oral contraceptive and the initial administration of the implant); a back-up method of contraception is not needed.125

Women switching from a progestin-only contraceptive injection: Insert the contraceptive implant on the same day as the next contraceptive injection would have been due; a back-up method of contraception is not needed.125

Women switching from a progestin-containing intrauterine device: Insert the contraceptive implant on the same day as the intrauterine device is removed; a back-up method of contraception is not needed.125

The contraceptive implant can be inserted immediately after a first-trimester abortion.125 If therapy with the contraceptive insert is not initiated within 5 days of a first-trimester abortion, follow the instructions for women who did not use hormonal contraception in the preceding month.125

The contraceptive implant can be inserted 21–28 days after a second-trimester abortion.125

The contraceptive implant can be inserted 21–28 days postpartum in women who are not exclusively breast-feeding; a back-up method of contraception is not needed.125 The implant can be inserted after the fourth postpartum week in women who are exclusively breast-feeding their infant.125 If implant insertion occurs >4 weeks postpartum, use back-up method of contraception for 7 days.125

Remove implant 3 years after insertion.125 At time of implant removal, may insert another implant to continue therapy.125


Levonorgestrel-releasing intrauterine contraceptive system (Mirena): One system containing 52 mg every 5 years.117

To initiate therapy, insert the intrauterine contraceptive system within 7 days of menses onset.117

The intrauterine contraceptive system can be inserted immediately after a first-trimester abortion; delay insertion until involution of the uterus is complete after a second-trimester abortion.117

The intrauterine contraceptive system should not be inserted until 6 weeks postpartum or after involution of the uterus is complete.117

Remove the intrauterine contraceptive system after 5 years of use (contraceptive efficacy >5 years not established).117 At time of system removal, may insert another intrauterine contraceptive system to continue therapy; removal and replacement with a new system can be done at any time during the menstrual cycle.117

For women with regular menstrual cycles who wish to initiate an alternative contraceptive method, remove the intrauterine system during the first 7 days of a menstrual cycle and start new method.117 For those with irregular cycles or amenorrhea or for those in whom the system is removed after the seventh day of the menstrual cycle, initiate the new contraceptive method at least 7 days before removal of the intrauterine system.117

Postcoital (Emergency) Contraception

Plan B One-Step: Single 1.5-mg dose taken as soon as possible within 72 hours of unprotected intercourse.132

Next Choice: 0.75-mg dose taken as soon as possible within 72 hours of unprotected intercourse, followed by a second 0.75-mg dose 12 hours later.101 102 106

If necessary, the first dose can be administered up to120 hours after unprotected intercourse,126 127 128 but efficacy decreases the longer initiation of contraception is delayed.101 102 103 126 127 128 129

Repeated postcoital (emergency) contraception use indicates need for counseling about other contraceptive options.126 131 Safety of recurrent use not established but risk appears low, even within same menstrual cycle.126 131 Consider possibility that risk of adverse effects may be increased with frequently repeated postcoital contraception.131

FDA has approved Plan B One-Step for OTC status for women ≥17 years of age.132 Plan B One-Step and Next Choice are prescription-only preparations for women <17 years of age.106 132

Cautions for Progestins


  • Known or suspected pregnancy.106 117 119 120 125 132

  • Undiagnosed vaginal bleeding.117 119 120 125

  • Known or suspected breast cancer.117 119 120 125

  • Benign or malignant liver tumor.117 119 120 125

  • Liver disease.117 119 120 125

  • Current or past history of thrombosis or thromboembolic disorders.125

  • Levonorgestrel-releasing intrauterine contraceptive system also is contraindicated in women with uterine abnormalities that distort the uterine cavity (e.g., fibroids), PID or history of PID (unless there has been a subsequent intrauterine pregnancy), postpartum endometritis or infected abortion in the past 3 months, untreated acute cervicitis or vaginosis, conditions associated with immune compromise (e.g., HIV, leukemia, IV drug abuse), a previously inserted IUD still in place, genital actinomycosis, history of ectopic pregnancy or predisposition for ectopic pregnancy, known or suspected uterine or cervical neoplasia, abnormal Papanicolaou test (Pap smear), and in women with multiple sexual partners or whose partners have multiple sexual partners.117

  • Postcoital (emergency) contraception: Manufacturer states that not known whether the conditions for contraindications of progestin-only oral contraceptives apply to the postcoital contraceptive regimen.106 Most experts state that there currently is no real contraindication to postcoital (emergency) contraception with the recommended levonorgestrel regimens and that the benefits generally outweigh any theoretical or proven risk.126 127 131

  • Hypersensitivity to the drug or any ingredient in the formulation.106 117 119 120 125



Ectopic Pregnancy

Consider the possibility of ectopic pregnancy if pregnancy or severe abdominal pain occurs in women using progestin contraception, including those using postcoital (emergency) regimens.106 117 119 120 125 132 Current evidence does not support increased risk of ectopic pregnancy after use of levonorgestrel for postcoital (emergency) contraception in the general population; rather, preventing pregnancy overall actually reduces absolute risk.126 127 Postcoital contraception with levonorgestrel can be used in women with history of ectopic pregnancy.106 131 132

Ovarian Follicles

Possible delayed atresia of ovarian follicles, resulting in follicular enlargement.117 119 120 125 Follicular enlargement generally is asymptomatic or associated with mild abdominal pain and resolves spontaneously; in rare cases, surgery may be required.117 119 120 125

Bleeding Irregularities

Possible breakthrough bleeding or irregular vaginal bleeding.117 119 120 125 Perform adequate diagnostic tests in patients with undiagnosed vaginal bleeding.117 119 120 125 Rule out pregnancy in patients with amenorrhea.117 119 120 125 If pregnancy occurs, discontinue therapy.117 119 120 125

Postcoital (emergency) contraception: Irregular vaginal bleeding also possible with postcoital contraceptive regimens;106 126 132 rule out pregnancy if menses is delayed >7 days after anticipated onset.106 132

Carcinoma of Breast and Reproductive Organs

Insufficient data to determine whether use of progestin-only contraceptives is associated with an increased risk of breast cancer or cervical carcinoma.117 119 120 125 (See Contraindications under Cautions.)

Hepatic Effects

Insufficient data to determine whether use of progestin-only contraceptives is associated with increased risk of hepatocellular carcinoma.119 120 (See Contraindications and also see Hepatic Impairment under Cautions.)

Implant Considerations

Carefully follow recommended procedures for insertion and removal of implant to minimize potential for complications.125

If infection develops at insertion site, initiate appropriate treatment; if infection persists, remove the implant.125

Intrauterine Device Considerations

Evaluate women for suitability (i.e., exclude pregnancy; evaluate for genital infections, risk for ectopic pregnancy, and/or PID) prior to insertion of levonorgestrel-releasing intrauterine device.117 Insert the device under strict aseptic conditions.117

Possible complications include intrauterine pregnancy with the device in place; if this occurs, remove device to reduce possibility of complications to the woman (e.g., septicemia, septic shock, death) and fetus (e.g., miscarriage, sepsis, premature labor, premature delivery).117 Long-term effects unknown if pregnancy is continued with the intrauterine device in place.117 (See Fetal/Neonatal Morbidity and Mortality under Cautions.)

Sepsis following insertion of the device reported rarely.117 Increased risk of infective endocarditis in women with valvular or congenital heart disease and in those with surgically constructed systemic-pulmonary shunts; prophylactic anti-infective therapy recommended at time of insertion for women with congenital heart disease.117

Other complications include penetration or embedment of the device in the myometrium and perforation of the uterus or cervix.117

Fetal/Neonatal Morbidity and Mortality

Congenital abnormalities reported infrequently in neonates born to women with a levonorgestrel-releasing intrauterine device in place during the pregnancy.117

Thromboembolic Disorders

Thromboembolic events (i.e., pulmonary embolism, stroke) reported in patients using etonogestrel implant (Implanon).125

General Precautions

Physical Examination and Follow-up

Annual medical history and physical examination advised with long-term progestin therapy.117 119 120 125 Physical examination may be deferred until after initiation of oral contraceptives if requested by the woman and judged appropriate by the clinician.119 120 Complete medical examination should be performed prior to initiating therapy with etonogestrel implant or levonorgestrel-releasing intrauterine system.117 125 Exercise particular care in women with family history of breast cancer or those who have breast nodules.125

Metabolic Effects

Slight deterioration in glucose tolerance and increases in plasma insulin reported.117 119 120 125 Monitor prediabetic and diabetic patients.106 117 119 120 125

Altered lipid metabolism (decreased HDL, HDL2, apolipoprotein A-I and A-II; increased hepatic lipase) noted; no change in total cholesterol, LDL, VLDL, or HDL3 observed.119 120 Closely monitor women with hyperlipidemia.125

Ocular Effects

Obtain ophthalmologist assessment for contact lens wearers who develop visual disturbances or changes in lens tolerance.125


Exercise caution in women with a history of depression; discontinue if severe depression recurs during use.125


Discontinue contraceptive and evaluate cause if migraine occurs or is exacerbated, or when new headache pattern develops that is recurrent, persistent, or severe.119 120

HIV and STDs

Does not protect against HIV infection or other sexually transmitted diseases (STDs).106 127 131 132

Specific Populations


Levonorgestrel-releasing intrauterine contraceptive system (Mirena): Category X.117

Rule out pregnancy prior to initiating therapy.117 119 120 125 Rule out pregnancy in patients with amenorrhea.117 119 120 125 If pregnancy occurs, discontinue therapy.117 119 120 125

Postcoital (emergency) contraception: No need to rule out pregnancy with postcoital contraceptive regimens.126 127 128 Postcoital contraceptive regimens (i.e., levonorgestrel, estrogen-progestins regimens) do not exhibit abortifacient properties126 127 128 and do not interrupt pregnancy once endometrial implantation has occurred.106 126 127 128 132 No known harm to pregnant woman, course of pregnancy, or fetus from postcoital contraceptive regimens.126 127 128 131

Most studies have revealed no effects on fetal development associated with long-term use of oral progestin contraceptives.106 119 120 126 127 128


Small amounts of progestins are distributed into milk.117 119 120 125 Adverse effects, such as jaundice, reported rarely in infants.120

Postcoital (emergency) contraception: Nursing can continue during postcoital contraceptive regimens.106 131

Pediatric Use

Safety and efficacy of progestin contraceptives have been established in women of reproductive age.106 117 119 120 125 132 Safety and efficacy are expected to be identical for postpubertal adolescents <16 years of age and users ≥16 years of age.106 119 120 125 128 Not indicated before menarche.106 117 119 120 125 132

Geriatric Use

Progestin contraceptives have not been evaluated in women >65 years of age and are not indicated in this population.117 125

Hepatic Impairment

Steroid hormones (including oral contraceptives) may be poorly metabolized in patients with hepatic dysfunction; use with caution in those individuals.125 (See Contraindications under Cautions.)

Postcoital (emergency) contraception: No precautions appear necessary with short-term postcoital contraceptive regimens; benefits outweigh any theoretical or known risk.126 131

Common Adverse Effects

Norethindrone tablets: Bleeding irregularities (e.g., frequent or irregular bleeding), headache, breast tenderness, nausea, dizziness.119 120

Levonorgestrel tablets: Nausea, abdominal pain, fatigue, headache, menstrual changes (e.g., heavier or lighter menstrual bleeding), dizziness, breast tenderness.106 126 127 128 129 132 Postcoital (emergency) contraceptive regimens better tolerated with levonorgestrel than with estrogen-progestins.126 127 128 129

Etonogestrel implants: Bleeding irregularities (e.g., frequent, heavy, or prolonged bleeding, spotting).125

Levonorgestrel-releasing intrauterine system: Abdominal pain, leukorrhea, headache, vaginitis, back pain, breast pain, acne, depression, hypertension, upper respiratory infection, nausea, nervousness, dysmenorrhea, weight increase, skin disorder, decreased libido, abnormal Pap smear, sinusitis.117

Interactions for Progestins

Specific Drugs



Anticonvulsants (carbamazepine, felbamate, oxcarbazepine, phenytoin, topiramate)

Possible reduced contraceptive efficacy106 119 120 125 132

Antifungal agents, azole

Possible increased plasma concentrations of contraceptive steroids with itraconazole or ketoconazole125

Anti-infective agents

Interaction unlikely with most anti-infective agents106 119

Antiretroviral agents

Possible changes in pharmacokinetics of orally administered progestins with some HIV protease inhibitors120 125 132 c


Possible reduced contraceptive efficacy106 119 120 125 132


Possible reduced contraceptive efficacy132


Possible reduced contraceptive efficacy125 132


Possible reduced contraceptive efficacy125


Possible reduced contraceptive efficacy106 119 120 125 132

St. John’s wort (Hypericum perforatum)

Possible reduced contraceptive efficacy120 125 132

Progestins Pharmacokinetics



Levonorgestrel: Rapidly absorbed following oral administration with peak plasma concentrations achieved in 1.6–1.7 hours.106 132 Bioavailability is about 100%.106

Norethindrone: Rapidly absorbed following oral administration with peak plasma concentrations achieved in 1–2 hours.119 120

Etonogestrel: Approximately 100% bioavailable following sub-Q administration.125 Following sub-Q insertion of etonogestrel implant, the drug is released at a rate of 60–70 mcg/day at week 5–6, 35–45 mcg/day at the end of year one, 30–40 mcg/day at the end of year two, and 25–30 mcg/day at the end of year three.125 Peak serum concentrations achieved in a few weeks following insertion of the implant.125

Levonorgestrel: Following insertion of a levonorgestrel-containing intrauterine system, drug is released into the uterine cavity at a rate of 20 mcg/day; rate of drug release decreases over time to about 10 mcg/day after 5 years of use.117


Effect of food on oral bioavailability not studied.106 120 132



Distributed into human milk.117 119 120 125

Plasma Protein Binding

Levonorgestrel: 50% bound to albumin and 47.5% bound to sex hormone binding globulin (SHBG).106 117

Norethindrone: 61% bound to albumin and 36% bound to SHBG.120

Etonogestrel: 66% bound to albumin and 32% bound to SHBG.125



Etonogestrel is metabolized in the liver by CYP3A4.125

Norethindrone is metabolized mainly by reduction, followed by sulfate and glucuronide conjugation.120

Elimination Route

Progestins are excreted in urine and feces, principally as metabolites and glucuronide and sulfate conjugates.106 117 119 120 125 132


Levonorgestrel (single oral dose): 24.4–27.5 hours.106 132

Norethindrone (single oral dose): Approximately 8 hours.120

Etonogestrel: Approximately 25 hours.125





Levonorgestrel: 20–25°C.106 132

Norethindrone: 25°C (may be exposed to 15–30°C).119 120


Etonogestrel implant (Implanon): 25°C (may be exposed to 15–30°C).125 Protect from light; avoid direct sunlight.125

Intrauterine System

Levonorgestrel-releasing intrauterine system (Mirena): 25°C (may be exposed to 15–30°C).117 System is supplied sterile; do not resterilize or use device if inner package is damaged or opened.117


  • Progestin contraceptives produce contraceptive effects by suppressing ovulation, thickening cervical mucus (thus inhibiting sperm migration into the uterus), lowering mid-cycle LH and FSH peaks, slowing ovum movement through the fallopian tubes, and/or alteration of the endometrium.117 119 120 125 126 127 a

  • Progestin contraceptives administered after intercourse (postcoital) produce contraceptive effects by inhibiting or delaying ovulation.106 126 132 Recent evidence suggests that any endometrial effects are insufficient to prevent implantation.126 127 Effects on ovulation alone cannot explain efficacy of postcoital (emergency) contraceptive; interference of sperm transport or penetration and/or impairment of corpus luteum function proposed as contributing factors.126 127 Only effective before pregnancy is established; not effective after implantation of a fertilized ovum.106 126 127 128 132

Advice to Patients

  • Importance of reading the manufacturer’s patient information.106 117 119 120 125 132

  • Importance of taking progestin-only oral contraceptives at the same time each day, without interruption (including during all bleeding episodes).119 120

  • Importance of using a backup method of contraception (e.g., condoms, spermicides) for each sexual encounter during the next 48 hours when a progestin-only oral contraceptive dose is ≥3 hours late.119 120

  • Next Choice postcoital (emergency) contraception: Importance of scheduling the initial dose as conveniently as possible (preferably no later than 72 hours after intercourse if possible) and of taking the second dose 12 hours after the initial dose.106

  • Postcoital (emergency) contraception: Therapy can be initiated up to 120 hours after intercourse if necessary, but advise of decreased efficacy as time from intercourse to initiation of contraception increases.126 127 128

  • Postcoital (emergency) contraception: Importance of consulting clinician about alternative methods of contraception if postcoital contraception is used repeatedly.127 131

  • Importance of informing women that progestin-only contraceptives, like all nonbarrier contraceptive methods, do not protect against HIV infection or other sexually transmitted diseases.106 117 119 120 125 132

  • Importance of advising patients of anticipated menstrual effects.117 119 120 125

  • Importance of women informing a clinician if prolonged (i.e., >8 days) or unusually heavy bleeding, amenorrhea, or severe abdominal pain occurs.117 119 120 125

  • Importance of women informing clinician if they are or plan to become pregnant or plan to breast-feed.106 117 119 120 125 Plan to breast-feed not relevant for postcoital (emergency) contraceptive regimens.126 127 128

  • Importance of women informing clinician of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as concomitant illnesses.117 119 120 125

  • Importance of informing patients of other important precautionary information.106 117 119 120 125 (See Cautions.)


Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

FDA has approved Plan B One-Step for OTC status for women ≥17 years of age; the contraceptive remains a prescription-only preparation for women <17 years of age.132 A commercial version of Plan B One-Step in a package that meets the prescription and OTC labeling requirements is available.132 Next Choice is a prescription-only preparation for women <17 years of age.106

The manufacturer (Wyeth) of levonorgestrel for sub-Q implantation (Norplant) ceased production of the implants and, because of ongoing shortages with product component supplies, has no plans to reintroduce them in the US.a The implant has not been available since August 2000.109 110



Dosage Forms


Brand Names




68 mg





Dosage Forms


Brand Names



Intrauterine System

52 mg





0.75 mg

Next Choice (available in pack of 2 tablets)


1.5 mg

Plan B One Step


Norethindrone (Norethisterone)


Dosage Forms


Brand Names




0.35 mg





Comparative Pricing

This pricing information is subject to change at the sole discretion of DS Pharmacy. This pricing information was updated 02/2014. Actual costs to patients will vary depending on the use of specific retail or mail-order locations and health insurance copays.

Progesterone 100MG Capsules (TEVA PHARMACEUTICALS USA): 30/$60.99 or 90/$169.97

Progesterone Micronized 200MG Capsules (TEVA PHARMACEUTICALS USA): 30/$115.99 or 90/$325.97

Prometrium 100MG Capsules (ABBOTT): 30/$72.99 or 90/$194.97

Prometrium 200MG Capsules (ABBOTT): 30/$127.00 or 90/$349.97

AHFS DI Essentials. © Copyright, 2004-2016, Selected Revisions May 1, 2010. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.

† Use is not currently included in the labeling approved by the US Food and Drug Administration.


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103. Glasierg A. Emergency postcoital contraception. N Engl J Med. 1997;337:1058-64.

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108. deVane PJ. Dear Norplant provider letter. Philadelphia, PA: Wyeth-Ayerst Pharmaceuticals; 2000 Aug 10.

109. deVane PJ. Dear health care provider letter: Important Norplant system (levonorgestrel implants) update. Philadelphia, PA: Wyeth-Ayerst Pharmaceuticals; 2000 Sep 13.

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115. FDA Statement. FDA takes action on Plan B: statement by FDA commissioner Lester M. Crawford. 2005 Aug 26. From FDA web site.

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118. Wyeth. Ovrette (norgestrel) tablets prescribing information. Philadelphia, PA; 2003 Oct.

119. Ortho-McNeil Pharmaceutical, Inc. Ortho Micronor (norethindrone) tablets prescribing information. Raritan, NJ; 2005 Oct.

120. Watson Pharma. Nor-QD (norethindrone 0.35 mg tablets) prescribing information. Corona, CA; 2006 Mar.

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125. Organon. Implanon (etonogestrel) implant prescribing information. Roseland, NJ; 2006 Jul.

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128. American Academy of Pediatrics Committee on Adolescence, Policy statement: contraception and adolescents. Pediatrics. 2007; 120:1135-48.

129. Cheng L, Gülmezoglu AM, Piaggio G et al for the Cochrane Collaboration. Interventions for emergency contraception (review). Cochrane Database of Systematic Reviews. 2008, Issue 2. Art. No.: CD001324. DOI: 10.1002/14651858.CD001324.pub3.

130. Polis CB, Schaffer K, Blanchard K et al for the Cochrane Collaboration. Advance provision of emergency contraception for pregnancy prevention (review). Cochrane Database of Systematic Reviews. 2007, Issue 2. Art. No.: CD005497. DOI: 10.1002.14651858.CD005497.pub2.

131. World Health Organization. Department of Reproductive Health and Research. Medical eligibility criteria for contraceptive use. 3rd ed. Geneva, Switzerland: World Health Organization; 2004.

132. Duramed Pharmaceuticals. Plan B One-Step (levonorgestrel) 1.5 mg tablets prescribing information. Pomona, NY; 2009 Jul.

a. AHFS Drug Information 2007. McEvoy GK, ed. Progestins. Bethesda, MD: American Society of Health-System Pharmacists; 2007: 3086-91.

b. Anon. Choice of Contraceptives. Treat Guidel Med Lett 2007: 5:101-8.

c. Department of Health and Human Services (DHHS) Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents (November 3, 2008). From the US Department of Health and Human Services HIV/AIDS Information Services (AIDSinfo) website.