Levonorgestrel Intrauterine System

Introduction Overview

Generic Name

levonorgestrel intrauterine system

Brand Name

Liletta

Dosage Form

intrauterine device (52 mg levonorgestrel)

Drug Class

Contraceptives, Progestins

Pharmacokinetics

Absorption:
Liletta functions as a levonorgestrel-releasing intrauterine system (IUS) where levonorgestrel, a synthetic progestin hormone, is released locally within the uterine environment. The drug reservoir of Liletta contains 52 mg of levonorgestrel, delivering an initial release rate of about 20 mcg per day, which gradually decreases over time to approximately 6.5 mcg per day after 8 years. Levonorgestrel is absorbed primarily through the endometrial tissue, allowing for effective local concentrations with minimal systemic bloodstream exposure compared to oral administration. This localized release minimizes systemic side effects while maintaining contraceptive efficacy and therapeutic effects on the uterine lining.

Distribution:
Due to its site-specific release, systemic levonorgestrel plasma concentrations remain relatively low but steady. The drug is distributed primarily within the uterine tissues affecting the endometrium and cervical mucus. Systemic distribution is limited but when present, levonorgestrel binds extensively to plasma proteins, mainly to sex hormone-binding globulin (SHBG) and albumin. The high local concentration in the uterus allows for effective symptom control, while systemic levels are typically insufficient to produce systemic hormonal effects commonly seen with oral or injectable progestins.

Metabolism:
Levonorgestrel released from Liletta undergoes extensive hepatic metabolism primarily via reduction and conjugation pathways. The hormone is metabolized mainly in the liver by cytochrome P450 enzymes to inactive metabolites which are then conjugated with glucuronic acid or sulfate and excreted. The local intrauterine delivery reduces first-pass metabolism concerns associated with oral progestins, contributing to more predictable pharmacological effects.

Elimination:
Elimination of levonorgestrel and its metabolites occurs predominantly through renal and fecal pathways. Following hepatic metabolism, conjugated metabolites are eliminated in urine and bile. The half-life of levonorgestrel varies depending on the delivery method, but intrauterine systems such as Liletta provide a sustained release, enabling continuous, slow elimination over years without significant peaks or troughs in systemic plasma levels. The device's removal effectively terminates hormone release and systemic exposure. Overall, this pharmacokinetic profile supports long-term contraceptive efficacy and treatment of heavy menstrual bleeding with favorable safety and tolerability.

Dosage Forms

Available Dosage Forms:
- Liletta is available as a single intrauterine system containing 52 mg of levonorgestrel embedded in a polydimethylsiloxane (PDMS) matrix within a T-shaped flexible plastic frame measuring 32 mm by 32 mm.
- The device has a translucent PDMS membrane controlling the hormone release.
- It includes a blue polypropylene monofilament removal thread for device retrieval, with colorant containing a copper-based pigment.

Dosages for Adults and Adolescents:
- The levonorgestrel IUS releases levonorgestrel initially at 20 mcg per day, progressively declining to 6.5 mcg per day over an 8-year period.
- It is FDA-approved for contraception use for up to 8 years.
- When used primarily for reducing heavy menstrual bleeding, Liletta is approved for use up to 5 years.
- The device is to be inserted by a healthcare professional into the uterine cavity.

Specific Patient Populations:
- Liletta can be used in women seeking long-acting reversible contraception and in those with heavy menstrual bleeding desiring medical management.
- It is safe to use during breastfeeding although there is a slightly increased risk of uterine wall perforation or device embedment in this population.
- It is contraindicated in women with certain uterine abnormalities, untreated pelvic infections, or recent pregnancy complications.
- Not recommended as an emergency contraceptive or for use in pregnancy.

Clinical Guidelines:
- Device insertion should ideally occur during the first seven days of the menstrual cycle or immediately following a first-trimester abortion or miscarriage for immediate contraceptive effect.
- If inserted at other times, a backup contraception method is recommended for the first 7 days.
- Device removal must be performed by a healthcare professional and can be safely done at any time when contraception is no longer desired.
- Another contraceptive method should be started at least seven days prior to removal to avoid pregnancy risk.
- Regular follow-up includes examination of device position and routine gynecologic care to monitor for possible complications.

Mechanism Of Action

Liletta operates through localized release of levonorgestrel, a synthetic progestin hormone, directly into the uterine environment. The primary mechanism involves thickening cervical mucus to impede sperm transport, thereby preventing fertilization. Levonorgestrel also modifies the endometrium by thinning the uterine lining, making it less suitable for implantation should fertilization occur.

At the cellular level, levonorgestrel binds to intracellular progesterone receptors in uterine tissue, altering gene expression that governs endometrial growth and secretory activity. This downregulation reduces endometrial proliferation and diminishes menstrual blood loss by stabilizing the lining and decreasing bleeding during menstruation. The hormone’s progestogenic effects further inhibit endometrial vascularization and glandular tissue hyperplasia.

Unlike systemic hormonal contraceptives, Liletta’s intrauterine delivery concentrates these effects locally, minimizing systemic hormonal exposure and associated side effects. Additionally, the thickened cervical mucus induced by levonorgestrel release creates a physical and biochemical barrier to sperm penetration and survival, significantly decreasing the likelihood of sperm meeting oocytes.

Clinical studies support Liletta's dual action in effective contraception and management of menorrhagia. Comparison with other levonorgestrel-releasing IUDs such as Mirena reveals similar mechanisms but slight variations in release rates and duration of clinical efficacy. Research demonstrates that Liletta’s decreasing hormone release over its lifespan maintains sustained contraceptive and therapeutic effects with an excellent safety profile, highlighting its important role in long-acting reversible contraception and menstrual bleeding management.

Pharmacological Actions

Local progestogenic effect on the endometrium resulting in thinning and stable uterine lining.
Thickening of cervical mucus to prevent sperm penetration and mobility.
Inhibition of sperm survival and motility within the uterine cavity.
Reduction of menstrual blood loss by controlling endometrial development and vascularization.
Sustained hormone release providing long-term contraceptive effects for up to 8 years.
Minimal systemic absorption reducing systemic hormonal side effects.
Prolonged intrauterine presence acting as both contraceptive and therapeutic device.
Reduction of heavy menstrual bleeding through direct endometrial modulation.
Prevention of uterine implantation through synergistic progestin effects.
Non-estrogenic progestin-only mechanism suitable for patients with estrogen contraindications.
Slowly declining levonorgestrel release rate maintaining efficacy over extended use.
Provision of reversible birth control with prompt return to fertility post-removal.
Physical presence of T-shaped device eliciting mild local inflammatory reaction impairing sperm function.

Therapeutic Or Clinical Uses

Long-acting reversible contraception for up to 8 years in women seeking pregnancy prevention.
Treatment of heavy menstrual bleeding (menorrhagia) to reduce menstrual blood loss.
Alternative to systemic hormonal contraceptives for patients who are contraindicated to estrogen.
Management of dysfunctional uterine bleeding through local progestin effects.
Reduction of menstrual pain related to heavy bleeding and endometrial stabilization.
Contraceptive option during lactation as it does not significantly affect breast milk.
Prevention of unwanted pregnancy in patients desiring nonpermanent contraception.
Effective in women with contraindications to combined hormonal contraceptives.
Adjunct in gynecologic conditions requiring endometrial suppression.
Option for patients with increased risk of venous thromboembolism avoiding systemic hormones.
Suitable for women unable to adhere to daily oral contraceptives due to compliance issues.
Alternative to surgical management for uterine fibroids causing bleeding (with caveats).
Used in clinical settings for patients intolerant of systemic progestins due to side effects.

Side Or Adverse Effects

Pelvic pain and cramping during or after device insertion.
Changes in menstrual bleeding patterns, including irregular, prolonged or spotting.
Painful menstruation or dysmenorrhea.
Vaginal swelling, itching, or infections such as candidiasis.
Intermittent dizziness and light-headedness particularly during insertion.
Formation of ovarian cysts presenting as transient pelvic pain resolving within three months.
Gastrointestinal symptoms such as nausea, vomiting, or bloating.
Headache, migraines, and mood changes including depression.
Back pain and breast tenderness or discomfort.
Weight gain, acne exacerbation, oily skin, and alterations in hair growth.
Decreased libido or loss of interest in sexual activity.
Localized puffiness or edema in face, hands, ankles, or feet.
Allergic reactions including hives, facial swelling, or breathing difficulty (rare).
Potential uterine perforation or embedment leading to device malposition or failure.
Risk of pelvic inflammatory disease, particularly within the first 20 days post-insertion.

Precautions

Do not use in pregnancy; device should be removed if pregnancy occurs to prevent complications.
Monitor regularly for signs of pelvic infection or sexually transmitted infections.
Avoid if there is unexplained abnormal vaginal bleeding until diagnosis is confirmed.
Use cautiously in patients with a history of liver disease or liver tumors.
Not suitable in women with uterine anomalies or fibroids deforming the uterine cavity.
Ensure no active pelvic inflammatory disease or untreated cervicitis prior to insertion.
Caution in immunocompromised patients due to increased infection risk.
Regular medical follow-up needed to verify device position and function.
Advise patients that the device does not protect against HIV or other STI transmission.
Assess for migraine history, hypertension, or cardiovascular conditions prior to use.
Inform patients about possible menstrual changes and advise to report severe pain or bleeding.
Recommend backup contraception for 7 days if device inserted outside the first 7 days of cycle.
Exercise care when inserting in breastfeeding women due to slightly increased uterine perforation risk.
Discourage self-removal and recommend professional removal by healthcare provider.
Educate about monitoring the presence of removal threads and to report if they are missing.

Warnings

Do not use Liletta during pregnancy to avoid risk of miscarriage, infection, or fetal harm.
Risk of serious pelvic infections that may threaten fertility or life, especially soon after insertion.
Potential uterine perforation or embedment necessitating surgical intervention.
Immediate medical attention needed if severe abdominal pain, heavy vaginal bleeding, or fever occur.
May increase risk of ectopic pregnancy; any signs of tubal pregnancy require prompt evaluation.
Device dislodgement can lead to loss of contraceptive efficacy and unintended pregnancy.
Use with caution in women with history of breast, cervical, or uterine cancers.
May cause hormonal side effects such as mood disorders or migraine exacerbations.
Insertion-related adverse effects include pain, bleeding, dizziness that must be monitored.
Not effective for emergency contraception use; alternative methods should be used for this indication.
Potential for dose-related systemic hormonal effects, although minimized by local delivery.
Interaction with other hormonal or liver-metabolized drugs could theoretically alter efficacy.
Ensure device is removed at recommended duration limit to prevent diminished contraceptive effect.
Advise patients that Liletta does not protect against sexually transmitted infections.
Report any signs of allergic reactions or unusual symptoms immediately.

Contraindication

Known or suspected pregnancy.
Allergy to levonorgestrel or any component of the device.
Unexplained abnormal vaginal bleeding or bleeding of unknown etiology.
Current pelvic inflammatory disease or recent PID without complete treatment.
Postpartum or postabortion infection within the past 3 months.
History or presence of uterine fibroids causing distortion of the uterine cavity.
Active malignancy of breast, cervix, or uterine body.
Serious liver disease including benign or malignant liver tumors.
Immunosuppressive conditions such as AIDS, leukemia, or active IV drug abuse.
Presence of another intrauterine device currently in situ.
Unresolved recent abortion or miscarriage less than 6 weeks prior.
Recent delivery within the past 6 weeks without uterine involution.
Untreated sexually transmitted infections at the time of insertion.
Hypersensitivity to silicone or other device components.
Severe distortions or anomalies of the uterine cavity precluding insertion.
Known or suspected breast carcinoma due to progestin hormone exposure.

Drug Interactions

Potential interactions with drugs that induce hepatic enzymes (e.g., rifampin, carbamazepine) may theoretically reduce levonorgestrel concentration, but clinical significance in IUS use is minimal.
Concurrent use of other hormonal contraceptives may not be necessary and could increase systemic hormone exposure.
Interactions with certain antibiotics that influence liver enzyme activity could alter hormone metabolism.
Inducers or inhibitors of cytochrome P450 enzymes may affect levonorgestrel metabolism.
Use with enzyme-inducing anticonvulsants might reduce contraceptive efficacy; monitoring and backup contraception are advised.
Concomitant use of herbal supplements like St. John’s Wort may reduce hormonal levels.
No significant interaction with non-hormonal drugs such as analgesics or antibiotics without enzyme effects.
Levonorgestrel IUS generally exhibits low systemic levels, minimizing systemic drug interactions compared to oral routes.
Potential interactions with antiretroviral therapies, requiring careful clinical assessment.
No known interactions significantly affecting device integrity or uterine compatibility.
Concurrent use with vitamin or supplement regimens is unlikely to impact device function but should be disclosed to healthcare providers.
Laboratory tests measuring hormone levels may be affected by levonorgestrel presence.
Limited data on interactions with herbal or alternative therapies; caution advised.
Inform healthcare providers of all medications to assess potential interaction risks.
Backup contraception recommended if systemic interacting medications are initiated.

Preparations Of The Drug

Liletta is supplied as a preloaded intrauterine system containing 52 mg of levonorgestrel.
The device consists of a T-shaped low-density polyethylene frame with barium sulfate to confer radio-opacity for X-ray visualization.
Levonorgestrel is embedded in a silicone-based polydimethylsiloxane (PDMS) drug reservoir forming a translucent membrane.
A blue polypropylene monofilament thread attached to the device facilitates removal and contains a copper-based colorant.
The device is packaged sterile for single-use only, with a specified shelf life stored at 20°C to 25°C.
Insertion tools and applicators are provided to allow precise placement within the uterine cavity by trained professionals.
No estrogen or other hormones are included in the preparation, making it a progestin-only device.
Device components are biocompatible and designed for long-term intrauterine retention with minimal local tissue irritation.
Sterility and biocompatibility testing ensure safety for implantation.
The preparation includes comprehensive labeling detailing insertion technique, indications, contraindications, and removal instructions.
The device is approved and distributed by AbbVie Inc. and manufactured by Odyssea Pharma, ensuring quality control standards.
Packaging includes patient information leaflets outlining expected effects, side effects, and cautions.
The device undergoes extensive stability and release rate testing to guarantee sustained levonorgestrel delivery over the intended lifespan.
Radiopacity of the device aids in verification of placement and tracking using imaging modalities if needed.
Removal threads are color-coded to facilitate easy identification during gynecologic examinations.