Skyla

2.1. Insertion Instructions

• •A complete medical and social history should be obtained to determine conditions that might influence the selection of a levonorgestrel-releasing intrauterine system (LNG IUS) for contraception. If indicated, perform a physical examination, and appropriate tests for any forms of genital or other sexually transmitted infections. [See Contraindications (4) and Warnings and Precautions (5.10).]
• •Follow the insertion instructions exactly as described in order to ensure proper placement and avoid premature release of Skyla from the inserter. Once released, Skyla cannot be re-loaded.
• •Skyla should be inserted by a trained healthcare provider. Healthcare providers should become thoroughly familiar with the insertion instructions before attempting insertion of Skyla.
• •Insertion may be associated with some pain and/or bleeding or vasovagal reactions (for example, syncope, bradycardia) or seizure in an epileptic patient, especially in patients with a predisposition to these conditions. Consider administering analgesics prior to insertion.

Timing of Insertion

• •Insert Skyla into the uterine cavity during the first seven days of the menstrual cycle or immediately after a first trimester abortion. Back up contraception is not needed when Skyla is inserted as directed.
• •Postpone postpartum insertion and insertions following second trimester abortions a minimum of six weeks or until the uterus is fully involuted. If involution is delayed, wait until involution is complete before insertion [see Warnings and Precautions (5.6, 5.7)].

Tools for Insertion

• •Gloves
• •Speculum
• •Sterile uterine sound
• •Sterile tenaculum
• •Antiseptic solution, applicator

• •Sterile gloves
• •Skyla with inserter in sealed package
• •Instruments and anesthesia for paracervical block, if anticipated
• •Consider having an unopened backup Skyla available
• •Sterile, sharp curved scissors

Preparation for insertion

• •Exclude pregnancy and confirm that there are no other contraindications to the use of Skyla.
• •Ensure that the patient understands the contents of the Patient Information Booklet and obtain the signed patient informed consent located on the last page of the Patient Information Booklet.
• •With the patient comfortably in lithotomy position, do a bimanual exam to establish the size, shape and position of the uterus.
• •Gently insert a speculum to visualize the cervix.
• •Thoroughly cleanse the cervix and vagina with a suitable antiseptic solution.
• •Prepare to sound the uterine cavity. Grasp the upper lip of the cervix with a tenaculum forceps and gently apply traction to stabilize and align the cervical canal with the uterine cavity. Perform a paracervical block if needed. If the uterus is retroverted, it may be more appropriate to grasp the lower lip of the cervix. The tenaculum should remain in position and gentle traction on the cervix should be maintained throughout the insertion procedure.
• •Gently insert a uterine sound to check the patency of the cervix, measure the depth of the uterine cavity in centimeters, confirm cavity direction, and detect the presence of any uterine anomaly. If you encounter difficulty or cervical stenosis, use dilatation, and not force, to overcome resistance. If cervical dilatation is required, consider using a paracervical block.

Insertion Procedure

Proceed with insertion only after completing the above steps and ascertaining that the patient is appropriate for Skyla. Ensure use of aseptic technique throughout the entire procedure.

• •Open the package (Figure 1). The contents of the package are sterile.

Figure 1: Opening the Skyla Package

• •Using sterile gloves, lift the handle of the sterile inserter and remove from the sterile package.

• •Push the slider forwardas far as possible in the direction of the arrow thereby moving the insertion tube over the Skyla T-body to load Skyla into the insertion tube (Figure 2). The tips of the arms will meet to form a rounded end that extends slightly beyond the insertion tube.

• •Maintain forward pressure with your thumb or forefinger on the slider. DO NOT move the slider downward at this time as this may prematurely release the threads of Skyla. Once the slider is moved below the mark, Skyla cannot be re-loaded .

• •Holding the slider in this forward position, set the upper edge of the flange to correspond to the uterine depth (in centimeters) measured during sounding (Figure 3).

Figure 3: Setting the flange

• •Continue holding the slider in this forward position. Advance the inserter through the cervix until the flange is approximately 1.5–2 cm from the cervix and then pause (Figure 4).

Figure 4. Advancing insertion tube until flange is 1.5 to 2 cm from the cervix

Do not force the inserter. If necessary, dilate the cervical canal.

• •While holding the inserter steady, move the slider down to the mark to release the arms of Skyla (Figure 5). Wait 10 seconds for the horizontal arms to open completely.

Advance the inserter gently towards the fundus of the uterus until the flange touches the cervix. If you encounter fundal resistance do not continue to advance. Skyla is now in the fundal position (Figure 6).Fundal positioning of Skyla is important to prevent expulsion.

Figure 6. Move Skyla into the fundal position

• •Holding the entire inserter firmly in place, release Skyla by moving the slider all the way down(Figure 7).

• •Continue to hold the slider all the way down while you slowly and gently withdraw the inserter from the uterus.
• • Using a sharp, curved scissor, cut the threads perpendicular, leaving about 3 cm visible outside of the cervix [cutting threads at an angle may leave sharp ends (Figure 8)]. Do not apply tension or pull on the threads when cutting to prevent displacing Skyla.

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Figure 8. Cutting the threads

•  Skyla insertion is now complete. Prescribe analgesics, if indicated. Keep a copy of the Consent Form with lot number for your records.

Important information to consider during or after insertion

• •If you suspect that Skyla is not in the correct position, check placement (for example, using transvaginal ultrasound). Remove Skyla if it is not positioned completely within the uterus. A removed Skyla must not be re-inserted.
• •If there is clinical concern, exceptional pain or bleeding during or after insertion, appropriate steps should be taken immediately to exclude perforation, such as physical examination and ultrasound.

2.2 Patient Follow-up

• •Patients should be reexamined and evaluated 4 to 6 weeks after insertion and once a year thereafter, or more frequently if clinically indicated.

2.3 Removal of Skyla

Timing of Removal

• •Skyla should not remain in the uterus after 3 years.
• •If pregnancy is not desired, the removal should be carried out during menstruation, provided the woman is still experiencing regular menses. If removal will occur at other times during the cycle, consider starting a new contraceptive method a week prior to removal. If removal occurs at other times during the cycle and the woman has had intercourse in the week prior to removal, she is at risk of pregnancy. [See Dosage and Administration (2.4).]

Tools for Removal

• •Gloves
• •Speculum

• •Sterile forceps

Removal Procedure

• •Remove Skyla by applying gentle traction on the threads with forceps (Figure 9).

Figure 9. Removal of Skyla

• •If the threads are not visible, determine location of Skyla by ultrasound [see Warnings and Precautions (5.10)].
• •If Skyla is found to be in the uterine cavity on ultrasound exam, it may be removed using a narrow forceps, such as an alligator forceps. This may require dilation of the cervical canal. After removal of Skyla, the system should be examined to ensure that it is intact.
• •Removal may be associated with some pain and/or bleeding or vasovagal reactions (for example, syncope, or a seizure in an epileptic patient).

2.4 Continuation of Contraception after Removal

• •If pregnancy is not desired and if a woman wishes to continue using Skyla, a new system can be inserted immediately after removal any time during the cycle.
• •If a patient with regular cycles wants to start a different birth control method, time removal and initiation of new method to ensure continuous contraception. Either remove Skyla during the first 7 days of the menstrual cycle and start the new method or start the new method at least 7 days prior to removing Skyla if removal is to occur at other times during the cycle.
• •If a patient with irregular cycles or amenorrhea wants to start a different birth control method, start the new method at least 7 days before removal.

3 DOSAGE FORMS AND STRENGTHS

Skyla is a LNG-releasing IUS consisting of a T-shaped polyethylene frame with a steroid reservoir containing a total of 13.5 mg LNG.

4 CONTRAINDICATIONS

The use of Skyla is contraindicated when one or more of the following conditions exist:

• •Pregnancy or suspicion of pregnancy; cannot be used for post-coital contraception
• •Congenital or acquired uterine anomaly including fibroids if they distort the uterine cavity
• •Acute pelvic inflammatory disease or a history of pelvic inflammatory disease unless there has been a subsequent intrauterine pregnancy
• •Postpartum endometritis or infected abortion in the past 3 months
• •Known or suspected uterine or cervical neoplasia
• •Known or suspected breast cancer or other progestin-sensitive cancer, now or in the past
• •Uterine bleeding of unknown etiology
• •Untreated acute cervicitis or vaginitis, including bacterial vaginosis or other lower genital tract infections until infection is controlled
• •Acute liver disease or liver tumor (benign or malignant)
• •Conditions associated with increased susceptibility to pelvic infections
• •A previously inserted IUD that has not been removed
• •Hypersensitivity to any component of this product

5 WARNINGS AND PRECAUTIONS

5.1 Ectopic Pregnancy

•  Evaluate women for ectopic pregnancy if they become pregnant with Skyla in place because the likelihood of a pregnancy being ectopic is increased with Skyla. Approximately half of pregnancies that occur with Skyla in place are likely to be ectopic. Also consider the possibility of ectopic pregnancy in the case of lower abdominal pain, especially in association with missed periods or if an amenorrheic woman starts bleeding.

The incidence of ectopic pregnancy in clinical trials with Skyla, which excluded women with a history of ectopic pregnancy, was approximately 0.1% per year. The risk of ectopic pregnancy in women who have a history of ectopic pregnancy and use Skyla is unknown. Women with a previous history of ectopic pregnancy, tubal surgery or pelvic infection carry a higher risk of ectopic pregnancy. Ectopic pregnancy may result in loss of fertility.

5.2 Intrauterine Pregnancy

If pregnancy occurs while using Skyla, remove Skyla because leaving it in place may increase the risk of spontaneous abortion and preterm labor. Removal of Skyla or probing of the uterus may also result in spontaneous abortion. In the event of an intrauterine pregnancy with Skyla, consider the following:

Septic abortion

In patients becoming pregnant with an IUD in place, septic abortion—with septicemia, septic shock, and death—may occur.

Continuation of pregnancy

If a woman becomes pregnant with Skyla in place and if Skyla cannot be removed or the woman chooses not to have it removed, warn her that failure to remove Skyla increases the risk of miscarriage, sepsis, premature labor and premature delivery. Follow her pregnancy closely and advise her to report immediately any symptom that suggests complications of the pregnancy.

Long-term effects and congenital anomalies

When pregnancy continues with Skyla in place, long-term effects on the offspring are unknown. With another LNG IUS, congenital anomalies in live births have occurred infrequently. No clear trend towards specific anomalies has been observed. Because of the local exposure of the fetus to LNG, the possibility of teratogenicity following exposure to Skyla cannot be completely excluded. Some observational data support a small increased risk of masculinization of the external genitalia of the female fetus following exposure to progestins at doses greater than those currently used for oral contraception. Whether these data apply to Skyla is unknown.

5.3 Sepsis

Severe infection or sepsis, including Group A streptococcal sepsis (GAS), have been reported following insertion of another LNG IUS. In some cases, severe pain occurred within hours of insertion followed by sepsis within days. Because death from GAS is more likely if treatment is delayed, it is important to be aware of these rare but serious infections. Aseptic technique during insertion of Skyla is essential in order to minimize serious infections such as GAS.

5.4 Pelvic Infection

Pelvic Inflammatory Disease (PID)

•  Skyla is contraindicated in the presence of known or suspected PID or in women with a history of PID unless there has been a subsequent intrauterine pregnancy [see Contraindications (4)]. IUDs have been associated with an increased risk of PID, most likely due to organisms being introduced into the uterus during insertion.¹ In clinical trials, PID was observed in 0.4% of women overall and occurred more frequently within the first year and most often within the first month after insertion of Skyla.
•  Promptly examine users with complaints of lower abdominal or pelvic pain, odorous discharge, unexplained bleeding, fever, genital lesions or sores. Remove Skyla in cases of recurrent endometritis or pelvic inflammatory disease, or if an acute pelvic infection is severe or does not respond to treatment.

PID is often associated with a sexually transmitted infection, and Skyla does not protect against sexually transmitted infection. The risk of PID is greater for women who have multiple sexual partners, and also for women whose sexual partner(s) have multiple sexual partners. Women who have had PID are at increased risk for a recurrence or re-infection. In particular, ascertain whether the woman is at increased risk of infection (for example, leukemia, acquired immune deficiency syndrome [AIDS], IV drug abuse).

PID may be asymptomatic but still result in tubal damage and its sequelae.

Following a diagnosis of PID, or suspected PID, bacteriologic specimens should be obtained and antibiotic therapy should be initiated promptly. Removal of Skyla after initiation of antibiotic therapy is usually appropriate. Guidelines for PID treatment are available from the Centers for Disease Control (CDC), Atlanta, Georgia.

Actinomycosis

Actinomycosis has been associated with IUDs. Symptomatic women should have Skyla removed and should receive antibiotics. The significance of actinomyces-like organisms on Pap smear in an asymptomatic IUD user is unknown, and so this finding alone does not always require Skyla removal and treatment. When possible, confirm a Pap smear diagnosis with cultures.

5.5 Bleeding Pattern Alterations

Skyla can alter the bleeding pattern and result in spotting, irregular bleeding, heavy bleeding, oligomenorrhea and amenorrhea. During the first 3–6 months of Skyla use, the number of bleeding and spotting days may be higher and bleeding patterns may be irregular. Thereafter, the number of bleeding and spotting days usually decreases but bleeding may remain irregular. Amenorrhea develops by the end of the first year of use in approximately 6% of Skyla users. In Skyla clinical trials, a total of 77 subjects out of 1,672 (4.6%) discontinued due to uterine bleeding complaints. Table 1 shows the bleeding patterns as documented in the Skyla clinical trials based on 90-day reference periods. Table 2 shows the number of bleeding and spotting days based on 28-day cycle equivalents.

¹Defined as subjects with no bleeding/spotting throughout the 90-day reference period

²Defined as subjects with 1 or 2 bleeding/spotting episodes in the 90-day reference period

³Defined as subjects with more than 5 bleeding/spotting episodes in the 90-day reference period

⁴Defined as subjects with bleeding/spotting episodes lasting more than 14 days in the 90-day reference period. Subjects with prolonged bleeding may also be included in one of the other categories (excluding amenorrhea)

⁵Defined as subjects with 3 to 5 bleeding/spotting episodes and less than 3 bleeding/spotting-free intervals of 14 or more days

⁶The End of year 3 result for irregular bleeding in particular is artificially inflated (46%) because removal was not timed to coincide with a complete 90-day reference period. The result from the preceding 90-day reference period (17%) provides a more relevant indication of the observed incidence near the end of the 3-year period.

Because irregular bleeding/spotting is common during the first months of Skyla use, exclude endometrial pathology (polyps or cancer) prior to the insertion of Skyla in women with persistent or uncharacteristic bleeding. If a significant change in bleeding develops during prolonged use, take appropriate diagnostic measures to rule out endometrial pathology. The possibility of pregnancy should be considered if menstruation does not occur within six weeks of the onset of a previous menstruation. Once pregnancy has been excluded, repeated pregnancy tests are generally not necessary in amenorrheic women unless indicated, for example, by other signs of pregnancy or by pelvic pain.

5.6 Perforation

Perforation (total or partial, including penetration/embedment of Skyla in the uterine wall or cervix) may occur most often during insertion, although the perforation may not be detected until sometime later. Perforation may reduce contraceptive efficacy and result in pregnancy. The incidence of perforation during clinical trials was < 0.1%.

If perforation occurs, locate and remove Skyla. Surgery may be required. Delayed detection or removal of Skyla in case of perforation may result in migration outside the uterine cavity, adhesions, peritonitis, intestinal perforations, intestinal obstruction, abscesses and erosion of adjacent viscera.

Clinical trials with Skyla excluded breast-feeding women. An interim analysis from a large postmarketing safety study with other IUDs shows an increased risk of perforation in lactating women. The risk of perforation may be increased if Skyla is inserted when the uterus is fixed retroverted or not completely involuted during the postpartum period. Delay Skyla insertion a minimum of six weeks or until involution is complete following a delivery or a second trimester abortion.

5.7 Expulsion

Partial or complete expulsion of Skyla may occur resulting in the loss of contraceptive protection. Expulsion may be associated with symptoms of bleeding or pain, or it may be asymptomatic and go unnoticed. Skyla typically decreases menstrual bleeding over time; therefore, an increase of menstrual bleeding may be indicative of an expulsion. The risk of expulsion may be increased when the uterus is not completely involuted. In clinical trials, a 3-year expulsion rate of 3.2% (54 out of 1665 subjects) was reported.

Delay Skyla insertion a minimum of six weeks or until uterine involution is complete following a delivery or a second trimester abortion. Remove a partially expelled Skyla. If expulsion has occurred, Skyla may be replaced within 7 days of a menstrual period after pregnancy has been ruled out.

5.8 Ovarian Cysts

Because the contraceptive effect of Skyla is mainly due to its local effects within the uterus, ovulatory cycles with follicular rupture usually occur in women of fertile age using Skyla. During clinical trials, ovarian cysts (reported as adverse reactions if they were abnormal, non-functional cysts and/or had a diameter >3 cm on ultrasound examination) were reported in 13.2% of women using Skyla. Most of these cysts are asymptomatic, although some may be accompanied by pelvic pain or dyspareunia. In most cases the ovarian cysts disappear spontaneously during two to three months observation. Persistent ovarian cysts should be evaluated. Surgical intervention is not usually required.

5.9 Breast Cancer

Women who currently have or have had breast cancer, or have a suspicion of breast cancer, should not use hormonal contraception because some breast cancers are hormone-sensitive [see Contraindications (4)].

Spontaneous reports of breast cancer have been received during postmarketing experience with another LNG IUS. Two observational studies have not provided evidence of an increased risk of breast cancer during the use of the other LNG IUS.

5.10 Clinical Considerations for Use and Removal

Use Skyla with caution after careful assessment if any of the following conditions exist, and consider removal of the system if any of them arise during use:

• •Coagulopathy or use of anticoagulants
• •Migraine, focal migraine with asymmetrical visual loss or other symptoms indicating transient cerebral ischemia
• •Exceptionally severe headache
• •Marked increase of blood pressure
• •Severe arterial disease such as stroke or myocardial infarction

In addition, consider removing Skyla if any of the following conditions arise during use [see Contraindications (4)]:

• •Uterine or cervical malignancy
• •Jaundice
• •If the threads are not visible or are significantly shortened they may have broken or retracted into the cervical canal or uterus. Consider the possibility that the system may have been displaced, (for example, expelled or perforated the uterus) [see Warnings and Precautions (5.6, 5.7). Exclude pregnancy and verify the location of Skyla, for example, by sonography, X-ray, or by gentle exploration of the cervical canal with a suitable instrument. If Skyla is displaced, remove it. A new Skyla may be inserted at that time or during the next menses if it is certain that conception has not occurred. If Skyla is in place with no evidence of perforation, no intervention is indicated.

5.11 Magnetic Resonance Imaging (MRI) Information

Non-clinical testing has demonstrated that Skyla is MR Conditional. Skyla can be safely scanned only under specific conditions:

• •Static magnetic field of 3 Tesla or less
• •Spatial gradient field of 36,000 Gauss/cm (T/m) or less
• •Maximum whole body averaged specific absorption rate (SAR) of 4W/kg in the First Level Controlled mode for 15 minutes of continuous scanning

In non-clinical testing, the Skyla produced a temperature rise of less than 1.8°C at a maximum whole body averaged specific absorption rate (SAR) of 2.9 W/kg, for 15 minutes of MR scanning at 3T using a transit/receive body coil.

MR Image quality may be compromised (that is, a small amount of artifact may occur) if the area of interest is in the exact same area or relatively close to the position of Skyla. Image artifact extended up to 5 mm from Skyla in a Gradient Echo pulse sequence.

6 ADVERSE REACTIONS

The following serious or otherwise important adverse reactions are discussed elsewhere in the labeling:

• •Ectopic Pregnancy [see Warnings and Precautions (5.1)]
• •Intrauterine Pregnancy [see Warnings and Precautions (5.2)]
• •Group A Streptococcal Sepsis (GAS) [see Warnings and Precautions (5.3)]
• •Pelvic Inflammatory Disease [see Warnings and Precautions (5.4)]
• •Bleeding Pattern Alterations [see Warnings and Precautions (5.5)]
• •Perforation [see Warnings and Precautions (5.6)]
• •Expulsion [see Warnings and Precautions (5.7)]
• •Ovarian Cysts [see Warnings and Precautions (5.8)]

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

The data described below reflect exposure to Skyla in 1,672 patients in two contraception studies, including 1,383 exposed for one year and 993 who completed the three year studies. The population was generally healthy, 18 to 40-year old females requesting contraception and predominately Caucasian (82.6%). The data cover more than 40,000 cycles of exposure. The frequencies of reported adverse drug reactions represent crude incidences.

Most common adverse reactions (occurring in ≥ 5% users) were increased bleeding (7.8%), vulvovaginitis (20.2%), abdominal/pelvic pain (18.9%), acne/seborrhea (15.0%), ovarian cyst (13.2%), headache (12.4%), dysmenorrhea (8.6%), breast pain/discomfort (8.6%) and nausea (5.5%).

In the contraception studies, 18% discontinued prematurely due to an adverse reaction. The most common adverse reactions leading to discontinuation (in >1% of users) were uterine bleeding complaints (4.6%), device expulsion (3.2%), acne/seborrhea (2.9%), abdominal pain (2.5%) dysmenorrhea/uterine spasms (2.0%) and pelvic pain (1.8%).

Other common adverse reactions (occurring in ≥ 1% users) by System Organ Class (SOC): The frequencies of adverse reactions observed in clinical trials are summarized in Table 3 by SOC (presented as crude incidences).

^a Ovarian cysts were reported as AEs if they were abnormal, non-functional cysts and/or had a diameter >3 cm on ultrasound examination

^b Not all bleeding alterations were captured as adverse reactions [see Warnings and Precautions (5.5)].

6.2 Postmarketing Experience

The following adverse reactions have been identified during post approval use of another LNG IUS. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

• •Hypersensitivity including rash, urticaria, and angioedema
• •Device breakage

7 DRUG INTERACTIONS

No drug-drug interaction studies have been conducted with Skyla.

Drugs or herbal products that induce enzymes, including CYP3A4, that metabolize progestins may decrease the serum concentrations of progestins.

Some drugs or herbal products that may decrease the serum concentration of LNG include:

• •Barbiturates
• •Bosentan
• •Carbamazepine
• •Efavirenz
• •Felbamate
• •Griseofulvin
• •Nevirapine
• •Oxcarbazepine
• •Phenytoin
• •Rifabutin
• •Rifampin
• •St. John’s wort
• •Topiramate

Significant changes (increase or decrease) in the serum concentrations of the progestin have been noted in some cases of co-administration with HIV protease inhibitors or with non-nucleoside reverse transcriptase inhibitors. CYP3A4 inhibitors such as itraconazole or ketoconazole may increase plasma hormone levels.

Consult the labeling of all concurrently used drugs to obtain further information about interactions with Skyla or the potential for enzyme alterations.

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

The use of Skyla during an existing or suspected pregnancy is contraindicated. Many studies have found no harmful effects on fetal development associated with long-term use of contraceptive doses of oral progestins. The few studies of infant growth and development that have been conducted with progestin-only pills have not demonstrated significant adverse effects. [See Contraindications (4) and Warnings and Precautions (5.1, 5.2).]

8.3 Nursing Mothers

In general, no adverse effects of progestin-only contraceptives have been found on breastfeeding performance or on the health, growth, or development of the infant. Isolated postmarketing cases of decreased milk production have been reported. Small amounts of progestins were observed to pass into the breast milk of nursing mothers who used another LNG IUS, resulting in detectable steroid levels in infant serum. [See Warnings and Precautions (5.6).]

8.4 Pediatric Use

Safety and efficacy of Skyla have been established in women of reproductive age. Efficacy is expected to be the same for postpubertal females under the age of 18 as for users 18 years and older. Use of this product before menarche is not indicated.

8.5 Geriatric Use

Skyla has not been studied in women over age 65 and is not approved for use in this population.

8.6 Hepatic Impairment

No studies were conducted to evaluate the effect of hepatic disease on the disposition of LNG released from Skyla [see Contraindications (4)].

8.7 Renal Impairment

No studies were conducted to evaluate the effect of renal disease on the disposition of LNG released from Skyla.

11 DESCRIPTION

Skyla (LNG-releasing intrauterine system) contains 13.5 mg of LNG, a progestin, and is intended to provide an initial release rate of approximately14 mcg/day of LNG after 24 days.

Levonorgestrel USP, (-)-13-Ethyl-17-hydroxy-18,19-dinor-17α-pregn-4-en-20-yn-3-one, the active ingredient in Skyla, has a molecular weight of 312.4, a molecular formula of C₂₁H₂₈O₂, and the following structural formula: