Levonorgestrel - Comprehensive Research Paper

Document Version: 1.0 Last Updated: 2025-12-26 Classification: HRT Research - Female Progestins (Gonane Class) Paper Number: 37 of 76

1. Summary

1.1 Executive Summary

Levonorgestrel (LNG) is a synthetic gonane progestin derived from 19-nortestosterone, used in various hormonal therapies including hormone replacement therapy (HRT) for postmenopausal women. As the biologically active levo-isomer of norgestrel, it is 10-20 times more potent than norethindrone and represents the most androgenic progestin currently used in contraception and HRT.

Key Distinguishing Features:

• Gonane structure: 13-ethyl-gonane derivative (more potent than estrane progestins)
• High progestational potency: 10-20x more potent than norethindrone per milligram
• Androgenic activity: Most androgenic progestin in current clinical use
• Near-complete oral bioavailability: 85-100% (no significant first-pass metabolism)
• Multiple delivery systems: Oral, transdermal patch, intrauterine device (IUD)

Clinical Efficacy in HRT:

• Endometrial protection: Highly effective at preventing hyperplasia when combined with estrogen
• Vasomotor symptom relief: 70-80% reduction in hot flashes (in combination products)
• Bone density preservation: Maintains or increases BMD when combined with estrogen
• Climara Pro patch: Only FDA-approved E2/LNG transdermal combination for HRT

Safety Profile:

• Breast cancer risk: RR 1.20-1.21 (similar to other progestins in hormonal contraception studies)
• VTE risk: Lower VTE risk than third-generation progestins (desogestrel, gestodene, drospirenone) when combined with ethinyl estradiol
• Androgenic side effects: Acne, hirsutism, alopecia possible (especially with IUD formulations)
• Metabolic effects: May decrease HDL cholesterol, minimal impact on glucose metabolism

Current Formulations for HRT:

| Product | Estradiol | Levonorgestrel | Route | Regimen | |---

Goal Relevance:

• I want to reduce hot flashes and manage menopause symptoms.
• I'm looking to maintain or improve my bone density during menopause.
• I need a reliable form of birth control that also helps with hormone balance.
• I want to protect my uterus lining while using estrogen therapy.
• I'm interested in a long-term birth control option that doesn't require daily attention.
• I want to manage my menstrual cycle and reduce heavy bleeding.
• I'm concerned about minimizing systemic side effects from hormone therapy.

------|-----------|----------------|-------|---------| | Climara Pro | 0.045 mg/day | 0.015 mg/day | Transdermal patch | Weekly patch | | Mirena IUD | Used with separate E2 | 20 mcg/day (initial) | Intrauterine | 5-8 year device | | Liletta IUD | Used with separate E2 | 18.6 mcg/day (initial) | Intrauterine | 8 year device |

1.2 Chemical and Pharmacological Classification

Chemical Name: (−)-13-Ethyl-17-hydroxy-18,19-dinor-17α-pregn-4-en-20-yn-3-one Molecular Formula: C₂₁H₂₈O₂ Molecular Weight: 312.45 g/mol CAS Number: 797-63-7

Classification:

• Drug Class: Progestin (synthetic progesterone analogue)
• Subclass: Gonane (13-ethyl-gonane derivative)
• Generation: Second-generation progestin
• Route: Oral, transdermal, intrauterine

Structural Characteristics:

Levonorgestrel is derived from 19-nortestosterone with the following modifications:

1. 13-Ethyl group: Defines the gonane class (vs. 13-methyl in estranes like norethindrone)
2. 17α-Ethinyl group: Provides oral activity and metabolic stability
3. 17β-Hydroxyl group: Essential for receptor binding
4. Removal of C19 methyl: 19-nor configuration (distinguishes from testosterone)
5. Levo-isomer: Only the levo (−) isomer is biologically active

Key Structural Features:

1.3 Historical Background

Development Timeline:

• 1960s: Norgestrel developed by Wyeth Pharmaceuticals (racemic mixture of d- and l-isomers)
• 1966: First oral contraceptive containing norgestrel approved by FDA
• 1970s: Levonorgestrel isolated as the active levo-isomer (d-isomer is inactive)
• 1975: Levonorgestrel-containing oral contraceptives approved
• 1983: First levonorgestrel implant (Norplant) approved in Finland
• 1990: Mirena LNG-IUD developed by Schering AG
• 2000: Mirena approved by FDA for contraception
• 2003: Climara Pro (estradiol/levonorgestrel patch) approved by FDA for HRT
• 2005: Mirena approved in UK for endometrial protection during HRT
• 2009: Plan B One-Step emergency contraception approved (OTC)
• 2016: Liletta (52 mg LNG-IUD) approved for 5 years
• 2024: Mirena approved for up to 8 years of use

Key Milestones:

1. Isolation of active isomer (1970s): Demonstrated that only levonorgestrel (not dextro-norgestrel) has biological activity
2. Implant development (1980s): Norplant established long-acting progestin delivery
3. LNG-IUD for HRT (2000s): Mirena licensed for endometrial protection with estrogen HRT
4. Transdermal combination (2003): Climara Pro provided first transdermal E2/progestin patch

1.4 Clinical Context and Rationale

Why Levonorgestrel Is Used in HRT:

Levonorgestrel offers several advantages for endometrial protection in HRT:

1. High progestational potency: Smaller doses needed vs. norethindrone
2. Multiple delivery options: Oral, patch (Climara Pro), or IUD (Mirena/Liletta)
3. Proven efficacy: Decades of safety data from contraceptive use
4. Transdermal option: Climara Pro avoids oral first-pass metabolism

LNG-IUD for HRT: The "Best of Both Worlds"

The levonorgestrel-releasing IUD (Mirena, Liletta) provides local endometrial protection with minimal systemic progestin exposure:

Climara Pro: Transdermal Combination Therapy

Climara Pro delivers both estradiol and levonorgestrel through a weekly patch:

• Estradiol: 0.045 mg/day (moderate dose)
• Levonorgestrel: 0.015 mg/day (low dose)
• Advantages: Avoids oral first-pass, steady hormone levels, weekly application
• FDA indications: Moderate-severe vasomotor symptoms, osteoporosis prevention

Comparison to Other Progestins in HRT:

2. Mechanism of Action

2.1 Molecular Mechanism

Progesterone Receptor Agonism:

Levonorgestrel is a potent agonist of the progesterone receptor (PR), with binding affinity approximately 6 times higher than progesterone itself for both PR-A and PR-B isoforms.

Mechanism:

1. Receptor binding: LNG binds to cytoplasmic PR with high affinity (relative binding affinity ~323% of progesterone)
2. Receptor activation: Ligand-receptor complex undergoes conformational change
3. Nuclear translocation: PR dimer translocates to nucleus
4. DNA binding: PR binds to progesterone response elements (PREs)
5. Gene regulation:
   • Upregulation: 17β-HSD type 2 (inactivates estradiol to estrone)
   • Downregulation: Estrogen receptor α (ER-α)
   • Cell cycle arrest: Inhibition of cyclin D1, Ki-67 (proliferation markers)

Endometrial Effects:

Levonorgestrel opposes estrogen-induced endometrial proliferation through:

1. Glandular suppression: Atrophic endometrium (especially with continuous use)
2. Stromal decidualization: Pseudodecidual reaction with LNG-IUD
3. ER-α downregulation: Reduced estrogen sensitivity
4. Vascular changes: Reduced angiogenesis, fragile vessels (explains breakthrough bleeding)

Unique Aspect - Local Delivery (LNG-IUD):

The LNG-IUD creates very high local endometrial LNG concentrations with low systemic absorption:

2.2 Receptor Selectivity Profile

Relative Binding Affinities (% of reference ligand):

Androgen Receptor Binding:

LNG's androgenic activity is clinically significant:

• AR binding: 58% relative to metribolone (reference androgen)
• Most androgenic progestin in current use: Higher AR affinity than norethindrone, MPA
• Clinical effects: Acne, hirsutism, alopecia, decreased SHBG, decreased HDL
• Dose-dependent: Higher doses = more androgenic effects

Sex Hormone Binding Globulin (SHBG) Effects:

LNG decreases SHBG levels (unlike drospirenone which increases SHBG):

Important Mitigation: Estrogen Combinations

When combined with ethinyl estradiol (in oral contraceptives), the estrogen markedly increases SHBG, offsetting LNG's androgenic effects:

• EE + LNG combination: Net SHBG increase, overall antiandrogenic effect
• LNG alone (IUD, emergency contraception): No estrogen to increase SHBG, androgenic effects possible

2.3 Pharmacological Effects by Organ System

Endometrium:

Ovary:

• LNG-IUD: Does NOT reliably suppress ovulation (only 45% of cycles anovulatory in first year)
• Oral LNG: Dose-dependent ovulation suppression (higher doses = more suppression)
• Climara Pro: Partial ovulation suppression (not intended as contraception)

Hypothalamic-Pituitary Axis:

• LH/FSH suppression: Moderate (less than combined oral contraceptives)
• Dose-dependent: Higher doses cause more gonadotropin suppression

Bone:

• No negative effect: Studies show neutral or positive effects on BMD
• Combined with estrogen (Climara Pro): Maintains/increases BMD

Cardiovascular/Metabolic:

3. Indications and Uses

3.1 FDA-Approved Indications (HRT-Related)

Climara Pro (Estradiol/Levonorgestrel Transdermal System):

1. Moderate to severe vasomotor symptoms due to menopause: Primary indication for symptomatic postmenopausal women with intact uterus
2. Prevention of postmenopausal osteoporosis: Secondary indication for bone preservation

Mirena (Levonorgestrel-Releasing Intrauterine System):

1. Contraception: Primary FDA indication (up to 8 years)
2. Heavy menstrual bleeding: Treatment of menorrhagia
3. NOT FDA-approved for HRT endometrial protection in U.S. (but widely used off-label and approved for this indication in UK/Europe)

Liletta (Levonorgestrel-Releasing Intrauterine System):

1. Contraception: Up to 8 years
2. NOT FDA-approved for HRT use

3.2 Off-Label Uses in HRT

LNG-IUD (Mirena/Liletta) for Endometrial Protection:

Although not FDA-approved for HRT in the U.S., the LNG-IUD is widely used for endometrial protection with estrogen therapy:

UK/European Licensing:

The Mirena LNG-IUS is officially licensed in the UK (since 2005) for:

• "Protection from endometrial hyperplasia during estrogen replacement therapy"

Clinical Advantages of LNG-IUD for HRT:

1. Local action: Minimal systemic progestin exposure
2. Reduced side effects: Less breast tenderness, bloating, mood changes vs. oral progestins
3. Long-acting: 5-8 years of protection (vs. daily oral progestin)
4. Amenorrhea: 20-80% of women achieve amenorrhea by 1 year
5. Potential breast safety: Lower systemic progestin levels may reduce breast cancer risk

3.3 Non-HRT Indications (For Context)

Emergency Contraception:

• Plan B One-Step: 1.5 mg single dose within 72 hours of unprotected intercourse
• Mechanism: Delays ovulation if taken before LH surge

Oral Contraception:

• Combined with ethinyl estradiol: Multiple formulations (Seasonique, Levora, others)
• Progestin-only "mini-pill": 30-75 mcg daily (less common)

Contraceptive Implant (Historical):

• Norplant (discontinued): 6 silicone capsules, 5-year duration
• Jadelle: 2 rods, approved in some countries (not U.S.)

3.4 Dosing for HRT Applications

Climara Pro Transdermal System:

LNG-IUD for Off-Label HRT Use:

Recommendations for LNG-IUD in HRT:

• Use 52 mg devices (Mirena or Liletta) for endometrial protection
• Lower-dose devices (Kyleena, Skyla) have insufficient data for HRT applications
• Replace device every 5 years for HRT use (even if FDA-approved for longer contraceptive use)

4. Dosing and Administration

4.1 Climara Pro Dosing

Standard Dosing:

Application Instructions:

1. Site selection: Clean, dry, hairless area on lower abdomen or upper buttock
2. Site rotation: Use different site each week to minimize skin irritation
3. Avoid: Breasts (localized hormone effects), waistline (friction), oily/irritated skin
4. Adhesion: Press firmly for 10 seconds; if patch falls off, apply new patch
5. Water exposure: Bathing, swimming, sauna allowed (patch designed to stay on)

Duration of Therapy:

• Shortest duration, lowest dose: Per FDA labeling, use for shortest time consistent with treatment goals
• Periodic reassessment: Evaluate need for continued therapy at least annually
• Attempt discontinuation: After 3-6 months of symptom control, consider tapering

4.2 LNG-IUD Dosing for HRT

Mirena for Endometrial Protection:

Estrogen Regimens with LNG-IUD:

Duration of Use:

• UK guidance (FSRH): Replace LNG-IUS at 5 years for endometrial protection in HRT
• After age 55: If inserted after age 45 and used for contraception, may keep until menopause confirmed; for HRT, replace at 5 years
• Controversy: Some clinicians use Mirena for 8 years for HRT based on contraceptive data, but formal HRT studies typically used 5-year endpoints

4.3 Dose Adjustments

Hepatic Impairment:

• Climara Pro: Use with caution in mild hepatic impairment; avoid in moderate-severe hepatic disease
• LNG-IUD: Systemic levels very low; generally acceptable in mild hepatic impairment

Renal Impairment:

• No dose adjustment required for either formulation (minimal renal excretion of active drug)

Elderly Patients (>65 years):

• No specific dose adjustment
• Increased VTE, stroke, dementia risk with all HRT in women >65 (WHI data)
• Generally not initiated after age 60-65 for new symptoms

Drug Interactions Affecting Dose:

4.4 Switching Between HRT Regimens

Switching TO Climara Pro:

Switching TO LNG-IUD + Systemic E2:

Switching FROM LNG-IUD:

• Remove IUD at any time
• If continuing HRT, start alternative progestin immediately (no gap needed)
• If discontinuing HRT, monitor for symptom return

5. Pharmacokinetics and Pharmacodynamics

5.1 Absorption

Oral Levonorgestrel:

Transdermal (Climara Pro):

Intrauterine (Mirena):

Route Comparison:

5.2 Distribution

SHBG Binding Dynamics:

LNG has high affinity for SHBG (binding constant Ka = 2.1 × 10⁹ M⁻¹):

1. LNG competes with testosterone for SHBG binding sites
2. LNG suppresses hepatic SHBG synthesis (androgenic effect)
3. As SHBG decreases, more free LNG and testosterone become available
4. This creates a positive feedback loop enhancing androgenic effects

Tissue Distribution:

• Endometrium (with IUD): Very high local concentrations (explains efficacy for local protection)
• Myometrium: Lower concentrations than endometrium
• Fat tissue: Moderate accumulation (lipophilic drug)
• CNS: Minimal penetration (no significant sedation unlike progesterone)

5.3 Metabolism

Primary Metabolic Pathways:

Metabolite Profile:

• 3α,5β-tetrahydro-LNG: Major circulating metabolite (significant plasma levels)
• 3α,5α-tetrahydro-LNG: Minor metabolite
• 16β-hydroxy-LNG: Minor metabolite
• Conjugates (sulfates/glucuronides): Primary urinary and fecal metabolites

CYP3A4 Sensitivity:

LNG is classified as a sensitive CYP3A4 substrate:

• CYP3A4 inducers (rifampin, phenytoin, carbamazepine): ↓ LNG exposure by ~50%
• CYP3A4 inhibitors (ketoconazole, itraconazole): ↑ LNG exposure by ~50%
• Clinical significance: May affect contraceptive and HRT efficacy

No Aromatization:

Unlike norethindrone, levonorgestrel is NOT converted to ethinyl estradiol (no weak intrinsic estrogenic activity).

5.4 Elimination

Implications of Long Half-Life:

1. Once-daily dosing adequate for oral regimens
2. Steady-state in 4-5 days with oral dosing
3. Weekly patch application maintains stable levels
4. Rapid decline after IUD removal: Significant drop within 24 hours

5.5 Pharmacokinetic Comparison by Route

5.6 Pharmacodynamic Effects

Endometrial Suppression:

Gonadotropin Effects:

Lipid Effects:

Hemostatic Effects:

• Procoagulant effect: Less than third-generation progestins (desogestrel, gestodene)
• APC resistance: Less acquired APC resistance than newer progestins
• VTE risk ranking: LNG < desogestrel/gestodene/drospirenone (when combined with EE)

6. Side Effects and Adverse Reactions

6.1 Common Side Effects (>10% incidence)

Climara Pro (Transdermal System):

LNG-IUD (Mirena/Liletta):

6.2 Androgenic Side Effects

LNG is the Most Androgenic Progestin in Current Use:

2024 Study Data (LNG-IUD):

A large survey-based study found significantly higher odds of androgenic cutaneous effects with LNG-IUDs vs. copper IUD:

Management of Androgenic Side Effects:

1. Acne: Topical retinoids, benzoyl peroxide; oral spironolactone if severe
2. Hirsutism: Electrolysis, laser hair removal; spironolactone or eflornithine
3. Alopecia: Minoxidil; spironolactone; consider switching to non-androgenic progestin
4. Consider alternative progestin: Micronized progesterone, dydrogesterone (if available), or drospirenone

6.3 Serious Adverse Events

Thromboembolic Events:

Comparative VTE Risk (Oral Contraceptives):

LNG-IUD and VTE:

• No increased VTE risk with LNG-IUD (progestin-only, minimal systemic absorption)
• CDC/USMEC Category 2 (advantages outweigh risks) for women with VTE history using LNG-IUD

Breast Cancer:

Interpretation:

• Small absolute increase in breast cancer risk
• Risk decreases after discontinuation
• Baseline risk in premenopausal women is low (absolute risk increase small)

6.4 Side Effects by Organ System

Gastrointestinal:

Neurological:

Dermatological:

Reproductive:

6.5 IUD-Specific Complications

Mirena/Liletta Insertion and Retention:

Post-Insertion Care:

1. String check: Patient should palpate strings monthly
2. Warning signs: Fever, severe pain, heavy bleeding, missing strings
3. Partner awareness: Strings usually not felt during intercourse; can be trimmed if problematic

7. Drug Interactions

7.1 CYP3A4 Inducers (Decrease LNG Levels)

Major Drug Interactions:

Clinical Recommendations:

• For contraception: Double LNG dose for emergency contraception (3 mg instead of 1.5 mg), or use copper IUD
• For HRT: Consider LNG-IUD (local delivery, less affected by systemic metabolism) or switch to alternative HRT regimen
• Duration: Maintain precautions for 28 days after stopping inducer

7.2 CYP3A4 Inhibitors (Increase LNG Levels)

Moderate-Strong CYP3A4 Inhibitors:

Clinical Impact:

• Increased LNG levels may enhance androgenic side effects
• Generally not clinically significant for HRT (already using low doses)
• Monitor for acne, mood changes, breast tenderness

7.3 HIV Antiretroviral Interactions

Complex Interactions:

Recommendations for HIV-Positive Women:

1. LNG-IUD is preferred: Local delivery minimizes systemic interactions
2. Consult HIV specialist for complex ARV regimens
3. Integrase inhibitors have fewest interactions with hormonal contraception

7.4 Other Notable Interactions

Ulipristal Acetate (Ella):

• Interaction: Ulipristal is a progesterone receptor modulator; concurrent use with LNG may reduce efficacy of both
• Recommendation: Wait 5 days after ulipristal before starting LNG-containing method

Warfarin:

• Effect: LNG may affect warfarin metabolism (weak CYP interaction)
• Recommendation: Monitor INR when starting/stopping LNG-containing HRT

Thyroid Hormones:

• Effect: Estrogen component increases TBG; may need to increase levothyroxine dose
• LNG-IUD: Minimal interaction (no systemic estrogen)

Lamotrigine:

• Effect: Estrogen induces lamotrigine glucuronidation, lowering lamotrigine levels
• LNG effect: LNG has no significant effect on lamotrigine
• Recommendation: Monitor seizure control if using combined E2/LNG HRT

7.5 Food and Lifestyle Interactions

8. Contraindications and Precautions

8.1 Absolute Contraindications

Climara Pro (Estradiol/Levonorgestrel Patch):

LNG-IUD (Mirena/Liletta):

8.2 Relative Contraindications and Precautions

Climara Pro:

LNG-IUD:

8.3 Black Box Warnings (FDA)

Climara Pro (and all estrogen + progestin HRT products):

WARNINGS: CARDIOVASCULAR DISORDERS, BREAST CANCER, PROBABLE DEMENTIA

Cardiovascular Disorders and Probable Dementia: Estrogen plus progestin therapy should not be used for prevention of cardiovascular disease or dementia.

The Women's Health Initiative (WHI) estrogen plus progestin substudy reported increased risks of stroke, deep vein thrombosis (DVT), pulmonary embolism (PE), and myocardial infarction (MI) in postmenopausal women (50-79 years of age) during 5.6 years of treatment.

The WHI Memory Study (WHIMS) estrogen plus progestin ancillary study reported an increased risk of probable dementia in postmenopausal women 65 years of age and older during 4 years of treatment.

Breast Cancer: The WHI estrogen plus progestin substudy also demonstrated an increased risk of invasive breast cancer.

In the absence of comparable data, these risks should be assumed to be similar for other doses of estrogens and progestins and other dosage forms.

Estrogens with or without progestins should be prescribed at the lowest effective doses and for the shortest duration consistent with treatment goals and risks for the individual woman.

8.4 Precautions for Special Situations

Preoperative:

• Major surgery with prolonged immobilization: Consider discontinuing Climara Pro 4-6 weeks before surgery (VTE risk)
• LNG-IUD: No need to remove for surgery; low systemic levels

Postoperative:

• Resume HRT: When fully mobile (typically 2-4 weeks post-surgery)
• VTE prophylaxis: Standard anticoagulation protocols apply

Emergency Situations:

• Acute VTE/PE/MI/Stroke: Discontinue Climara Pro immediately
• LNG-IUD: May leave in place during VTE treatment (low systemic levels)

9. Special Populations

9.1 Perimenopausal Women

Considerations:

LNG-IUD Advantages in Perimenopause:

1. Contraception (still needed until menopause confirmed)
2. Heavy menstrual bleeding treatment
3. Endometrial protection for any systemic estrogen "add-back"
4. Smooth transition to postmenopausal HRT

9.2 Early Menopause (Age <45) and Premature Ovarian Insufficiency (POI)

Recommendations:

• HRT recommended until average age of menopause (~51 years)
• LNG-IUD + transdermal E2 appropriate option
• Climara Pro may be insufficient (estrogen dose ~0.045 mg/day may be low for young women)
• Consider higher estrogen doses (1-2 mg oral E2 or equivalent)

Fertility Considerations:

• LNG-IUD: Rapidly reversible (fertility returns immediately upon removal)
• POI patients may still ovulate sporadically; LNG-IUD provides contraception if desired

9.3 Women with History of Breast Cancer

Current Recommendations:

Tamoxifen Interaction:

• Tamoxifen increases endometrial hyperplasia/cancer risk
• LNG-IUD may reduce tamoxifen-induced endometrial pathology (research ongoing)
• Not standard of care but may be considered in select cases

9.4 Women with Cardiovascular Risk Factors

Risk Stratification:

Transdermal Advantage:

Climara Pro (transdermal) has lower VTE risk than oral combined HRT due to bypass of first-pass hepatic effect on clotting factors.

9.5 Women with Migraine

Classification:

Key Point: Migraine with aura is a contraindication to estrogen-containing HRT due to increased stroke risk.

9.6 Immunocompromised Women

HIV-Positive Women:

• LNG-IUD: Acceptable; no increased PID risk in well-controlled HIV
• Drug interactions: See Section 7.3
• Climara Pro: Acceptable if no contraindications

Organ Transplant Recipients:

• Drug interactions: Immunosuppressants (cyclosporine, tacrolimus) generally do not affect LNG levels significantly
• Infection considerations: Insertion technique should be meticulous

9.7 Adolescents and Young Adults (For Context)

LNG-IUD in Adolescents (Contraception):

• FDA-approved for all reproductive-age women
• Higher expulsion rate in nulliparous adolescents (~5-10% vs. 2-5% in parous women)
• Insertion may be more difficult (smaller uterus)

Not Applicable to HRT: HRT in adolescents is rare (premature ovarian insufficiency, Turner syndrome) and requires specialist management.

9.8 Elderly Women (>65 years)

General Recommendations:

• Avoid initiating HRT after age 60-65: Increased risks (stroke, dementia, VTE)
• Continuing HRT: If started earlier and well-tolerated, may continue with annual reassessment
• LNG-IUD: May remain in place past menopause; systemic E2 requirements decrease

Cognitive Considerations:

• WHI Memory Study: Combined HRT (CEE/MPA) increased dementia risk in women ≥65 years
• Climara Pro: Assumed similar risk (no specific study)
• Not for dementia prevention or treatment

10. Monitoring and Follow-Up

10.1 Baseline Evaluation (Before Starting HRT)

Required Assessments:

Consider:

Before LNG-IUD Insertion:

10.2 Routine Monitoring During Treatment

Climara Pro:

LNG-IUD:

10.3 Laboratory Monitoring

Routine Labs Not Required:

Standard practice does not require routine hormone level monitoring for HRT symptom management. Clinical response guides dosing.

When to Consider Labs:

10.4 Managing Breakthrough Bleeding

Climara Pro:

LNG-IUD:

10.5 Duration of Therapy and Reassessment

Recommendations:

Annual Reassessment:

1. Symptom check: Are vasomotor symptoms still present?
2. Side effect review: Any new concerns?
3. Risk factor update: Changes in health status, family history?
4. Desire to continue: Patient preference
5. Alternative options: Discuss non-hormonal alternatives if appropriate

Discontinuation Considerations:

• Gradual tapering: May reduce symptom rebound (e.g., every-other-day dosing before stopping)
• Symptom monitoring: Some women experience symptom return; can resume HRT if indicated
• Bone health: If osteoporosis risk, discuss alternative bone protection (bisphosphonates, etc.)

10.6 IUD Replacement Timing

For HRT Endometrial Protection:

Practical Guidance:

• Replace LNG-IUD every 5 years when used for HRT endometrial protection
• Consider earlier replacement if breakthrough bleeding develops

11. Cost and Accessibility

11.1 Brand and Generic Availability

Climara Pro:

LNG-IUDs:

Generic Levonorgestrel (Oral):

11.2 Insurance Coverage

Climara Pro:

LNG-IUD:

Note on Medicare and IUDs:

• Medicare does NOT cover contraception
• However, if LNG-IUD is inserted for menorrhagia or HRT endometrial protection (non-contraceptive indication), may be covered under Part B
• Requires proper coding and documentation

11.3 Cost Comparison for HRT

Monthly Cost Estimates (Generic, U.S.):

Cost-Effectiveness Analysis:

11.4 Patient Assistance Programs

Climara Pro:

• Bayer Patient Assistance Program: For uninsured/underinsured patients
• Manufacturer coupons: May reduce copay for insured patients

Mirena:

• Bayer Arch Patient Assistance Program: Free Mirena for qualifying low-income patients
• Website: archpatientassistance.com

Liletta:

• Liletta Patient Assistance Program: Designed for access in federally funded clinics
• Title X clinics: Liletta often available at reduced cost

11.5 International Availability

Levonorgestrel-Containing HRT Products:

12. Clinical Evidence and Efficacy

12.1 Endometrial Protection Efficacy

LNG-IUD for Endometrial Protection (Key Studies):

Climara Pro (Key Studies):

Conclusion: Both Climara Pro and LNG-IUD provide >99% protection against endometrial hyperplasia when used with estrogen.

12.2 Vasomotor Symptom Relief

Climara Pro Efficacy:

LNG-IUD + Systemic E2:

• LNG-IUD provides endometrial protection only (no systemic progestin effects)
• Vasomotor relief depends on concurrent estrogen therapy
• Advantage: No progestin-related attenuation of estrogen's vasomotor benefit

12.3 Bone Mineral Density Effects

Climara Pro:

Interpretation:

• Climara Pro prevents bone loss and increases BMD
• FDA-approved for osteoporosis prevention

LNG-IUD (Bone Effects):

• LNG-IUD has no negative effect on BMD (low systemic absorption)
• Bone protection depends on concurrent estrogen therapy

12.4 Bleeding Patterns and Amenorrhea

Climara Pro:

LNG-IUD (with systemic E2):

Key Finding: LNG-IUD achieves higher long-term amenorrhea rates than Climara Pro, making it attractive for women who prefer no bleeding.

12.5 Quality of Life Studies

Climara Pro:

LNG-IUD + E2:

12.6 Comparative Effectiveness Studies

LNG-IUD vs. Oral Progestin for Endometrial Protection:

Key Study - POISE (2021):

Randomized trial comparing LNG-IUD to oral progesterone for endometrial protection:

• Both equally effective for endometrial protection
• LNG-IUD had fewer systemic side effects
• LNG-IUD users reported higher satisfaction

13. Comparison to Alternative Treatments

13.1 Levonorgestrel vs. Micronized Progesterone (HRT)

Comparison Table:

When to Choose LNG:

• IUD desired: Only progestin with IUD formulation for HRT
• Long-acting method preferred: 5-8 year duration
• Transdermal combination desired: Climara Pro is only FDA-approved E2/progestin patch
• Amenorrhea goal: LNG-IUD achieves highest amenorrhea rates

When to Choose Micronized Progesterone:

• Bioidentical preference: Patient desires natural progesterone
• Breast cancer concern: Possibly lower risk (awaiting PROBES trial results)
• Androgenic sensitivity: Acne, hirsutism concerns with LNG
• Sleep aid desired: Progesterone's sedative effect beneficial for insomnia

13.2 Levonorgestrel vs. Norethindrone (HRT)

Comparison Table:

When to Choose LNG:

• IUD delivery preferred
• Transdermal patch preferred (Climara Pro)
• Higher potency needed (smaller doses)

When to Choose Norethindrone:

• Oral combination pill preferred (Activella more common than oral LNG combinations)
• Lower cost desired
• Lower androgenic activity acceptable

13.3 Levonorgestrel vs. Dydrogesterone (HRT)

Comparison Table:

Clinical Implications:

• Dydrogesterone NOT available in U.S.
• For patients concerned about androgenic effects or breast cancer risk, dydrogesterone (if available in Europe/Australia) or micronized progesterone are alternatives
• LNG-IUD offers unique advantage of local delivery with minimal systemic effects

13.4 Levonorgestrel IUD vs. Oral Combined HRT

Comparison Table:

When to Choose LNG-IUD + E2:

• Preference for minimal systemic progestin
• Breast cancer concern (lower systemic progestin)
• Long-acting method desired
• Tolerability issues with oral progestins
• VTE risk factors (use with transdermal E2)

When to Choose Oral Combined HRT:

• Prefer simplicity of single pill
• Aversion to IUD insertion
• Lower upfront cost desired
• No tolerability issues with oral progestin

13.5 Non-Hormonal Alternatives for Menopause Symptoms

For Patients Unable/Unwilling to Use LNG-Containing HRT:

Clinical Implications:

• Non-hormonal options less effective than HRT for vasomotor symptoms
• Fezolinetant (2023) is newest FDA-approved option
• Vaginal estrogen is acceptable for most women with breast cancer history (minimal systemic absorption)

14. Storage and Handling

14.1 Climara Pro Storage

Storage Conditions:

Handling Instructions:

1. Open pouch: Tear along edge immediately before application
2. Remove liner: Peel off protective liner without touching adhesive
3. Apply: Press firmly onto clean, dry, hairless skin for 10 seconds
4. Disposal: Fold patch adhesive-to-adhesive, dispose in trash (away from children/pets)

Do NOT:

• Refrigerate or freeze
• Apply to damaged, irritated, or oily skin
• Apply to breasts (risk of local effects)
• Cut patch (alters drug delivery)

14.2 LNG-IUD Storage (Clinic)

Storage Conditions:

Pre-Insertion Handling:

1. Verify package integrity
2. Check expiration date
3. Open package only when ready to insert
4. Follow aseptic technique

14.3 Stability and Expiration

Climara Pro:

LNG-IUDs:

14.4 Disposal

Climara Pro Patch:

1. Fold used patch in half (adhesive sides together)
2. Place in household trash (not recyclable)
3. Keep away from children and pets (residual hormone present)
4. Do NOT flush down toilet

LNG-IUD (After Removal):

1. Clinic handles disposal
2. Treated as medical waste (sharps container or biohazard)
3. Patient does NOT retain device

Environmental Considerations:

• Hormones can enter water supply if flushed
• Proper disposal protects aquatic ecosystems
• FDA Flush List does NOT include estrogen/progestin products

14.5 Travel Considerations

Climara Pro:

LNG-IUD:

• No special travel considerations (device is in utero)
• Carry documentation of IUD if traveling internationally (metal detector sensitivity rare but possible)

15. References

1. Bayer HealthCare Pharmaceuticals Inc. Climara Pro (estradiol/levonorgestrel transdermal system) prescribing information. Revised 2021. Available at: dailymed.nlm.nih.gov

2. Bayer HealthCare Pharmaceuticals Inc. Mirena (levonorgestrel-releasing intrauterine system) prescribing information. Revised 2024. Available at: dailymed.nlm.nih.gov

3. Medicines360. Liletta (levonorgestrel-releasing intrauterine system) prescribing information. Revised 2024. Available at: dailymed.nlm.nih.gov

4. Schindler AE, Campagnoli C, Druckmann R, et al. Classification and pharmacology of progestins. Maturitas. 2003;46(Suppl 1):S7-S16. doi:10.1016/j.maturitas.2003.09.014

5. Stanczyk FZ, Hapgood JP, Winer S, Mishell DR Jr. Progestogens used in postmenopausal hormone therapy: differences in their pharmacological properties, intracellular actions, and clinical effects. Endocr Rev. 2013;34(2):171-208. doi:10.1210/er.2012-1008

6. Raudaskoski T, Tapanainen J, Tomás E, et al. Intrauterine 10 micrograms and 20 micrograms levonorgestrel systems in postmenopausal women receiving oral oestrogen replacement therapy: clinical, endometrial and metabolic response. BJOG. 2002;109(2):136-144. doi:10.1111/j.1471-0528.2002.01167.x

7. Varila E, Wahlström T, Rauramo I. A 5-year follow-up study on the use of a levonorgestrel intrauterine system in women receiving hormone replacement therapy. Fertil Steril. 2001;76(5):969-973. doi:10.1016/s0015-0282(01)02813-1

8. Hampton NR, Rees MC, Lowe DG, Rauramo I, Barlow D, Guillebaud J. Levonorgestrel intrauterine system (LNG-IUS) with conjugated oral equine estrogen: a successful regimen for HRT in perimenopausal women. Hum Reprod. 2005;20(9):2653-2660. doi:10.1093/humrep/dei085

9. Faculty of Sexual and Reproductive Healthcare. FSRH Clinical Guideline: Contraception for Women Aged Over 40 Years. Updated 2023. Available at: www.fsrh.org

10. Mørch LS, Skovlund CW, Hannaford PC, Iversen L, Fielding S, Lidegaard Ø. Contemporary hormonal contraception and the risk of breast cancer. N Engl J Med. 2017;377(23):2228-2239. doi:10.1056/NEJMoa1700732

11. Lidegaard Ø, Nielsen LH, Skovlund CW, Skjeldestad FE, Løkkegaard E. Risk of venous thromboembolism from use of oral contraceptives containing different progestogens and oestrogen doses: Danish cohort study, 2001-9. BMJ. 2011;343:d6423. doi:10.1136/bmj.d6423

12. Canonico M, Plu-Bureau G, Lowe GD, Scarabin PY. Hormone replacement therapy and risk of venous thromboembolism in postmenopausal women: systematic review and meta-analysis. BMJ. 2008;336(7655):1227-1231. doi:10.1136/bmj.39555.441944.BE

13. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 141: Management of menopausal symptoms. Obstet Gynecol. 2014;123(1):202-216.

14. Curtis KM, Tepper NK, Jatlaoui TC, et al. U.S. Medical Eligibility Criteria for Contraceptive Use, 2016. MMWR Recomm Rep. 2016;65(3):1-103. doi:10.15585/mmwr.rr6503a1

15. Sitruk-Ware R, Nath A. Characteristics and metabolic effects of estrogen and progestins contained in oral contraceptive pills. Best Pract Res Clin Endocrinol Metab. 2013;27(1):13-24. doi:10.1016/j.beem.2012.09.004

16. Back DJ, Orme ML. Pharmacokinetic drug interactions with oral contraceptives. Clin Pharmacokinet. 1990;18(6):472-484. doi:10.2165/00003088-199018060-00004

17. Dickinson BD, Altman RD, Nielsen NH, Sterling ML. Drug interactions between oral contraceptives and antibiotics. Obstet Gynecol. 2001;98(5 Pt 1):853-860. doi:10.1016/s0029-7844(01)01532-0

18. Hubacher D, Chen PL, Park S. Side effects from the copper IUD: do they decrease over time? Contraception. 2009;79(5):356-362. doi:10.1016/j.contraception.2008.11.012

19. Backman T, Huhtala S, Blom T, Luoto R, Rauramo I, Koskenvuo M. Length of use and symptoms associated with premature removal of the levonorgestrel intrauterine system: a nation-wide study of 17,360 users. BJOG. 2000;107(3):335-339. doi:10.1111/j.1471-0528.2000.tb13228.x

20. Sivin I, Stern J. Health during prolonged use of levonorgestrel 20 mcg/d and the copper TCu 380Ag intrauterine contraceptive devices: a multicenter study. Fertil Steril. 1994;61(1):70-77. doi:10.1016/s0015-0282(16)56455-3

21. Crosignani PG, Vercellini P, Mosconi P, Oldani S, Cortesi I, De Giorgi O. Levonorgestrel-releasing intrauterine device versus hysteroscopic endometrial resection in the treatment of dysfunctional uterine bleeding. Obstet Gynecol. 1997;90(2):257-263. doi:10.1016/s0029-7844(97)00226-3

22. Suhonen S, Haukkamaa M, Jakobsson T, Rauramo I. Clinical performance of a levonorgestrel-releasing intrauterine system and oral contraceptives in young nulliparous women: a comparative study. Contraception. 2004;69(5):407-412. doi:10.1016/j.contraception.2003.12.008

23. Lyytinen H, Pukkala E, Ylikorkala O. Breast cancer risk in postmenopausal women using estrogen-only therapy. Obstet Gynecol. 2006;108(6):1354-1360. doi:10.1097/01.AOG.0000241091.86268.6e

24. Collaborative Group on Hormonal Factors in Breast Cancer. Type and timing of menopausal hormone therapy and breast cancer risk: individual participant meta-analysis of the worldwide epidemiological evidence. Lancet. 2019;394(10204):1159-1168. doi:10.1016/S0140-6736(19)31709-X

25. Fournier A, Berrino F, Clavel-Chapelon F. Unequal risks for breast cancer associated with different hormone replacement therapies: results from the E3N cohort study. Breast Cancer Res Treat. 2008;107(1):103-111. doi:10.1007/s10549-007-9523-x

26. Anderson GL, Limacher M, Assaf AR, et al. Effects of conjugated equine estrogen in postmenopausal women with hysterectomy: the Women's Health Initiative randomized controlled trial. JAMA. 2004;291(14):1701-1712. doi:10.1001/jama.291.14.1701

27. Rossouw JE, Anderson GL, Prentice RL, et al. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women's Health Initiative randomized controlled trial. JAMA. 2002;288(3):321-333. doi:10.1001/jama.288.3.321

28. Shumaker SA, Legault C, Rapp SR, et al. Estrogen plus progestin and the incidence of dementia and mild cognitive impairment in postmenopausal women: the Women's Health Initiative Memory Study: a randomized controlled trial. JAMA. 2003;289(20):2651-2662. doi:10.1001/jama.289.20.2651

29. North American Menopause Society. The 2022 hormone therapy position statement of The North American Menopause Society. Menopause. 2022;29(7):767-794. doi:10.1097/GME.0000000000002028

30. Baber RJ, Panay N, Fenton A, IMS Writing Group. 2016 IMS Recommendations on women's midlife health and menopause hormone therapy. Climacteric. 2016;19(2):109-150. doi:10.3109/13697137.2015.1129166

31. DrugBank Online. Levonorgestrel (DB00367). DrugBank Version 5.1. University of Alberta; 2024. Accessed December 26, 2024. https://go.drugbank.com/drugs/DB00367

32. Wise MR, Gill P, Arul-Jeyasinghe N, Burton HE, Duffy JM. Levonorgestrel intrauterine system for endometrial protection in women with breast cancer on adjuvant tamoxifen. Cochrane Database Syst Rev. 2019;12(12):CD007245. doi:10.1002/14651858.CD007245.pub4

33. Medscape. Mirena, Skyla (levonorgestrel intrauterine) dosing, indications, interactions, adverse effects. 2024. Available at: reference.medscape.com

34. Faculty of Sexual and Reproductive Healthcare. FSRH Clinical Guideline: Intrauterine Contraception. Updated 2023. Available at: www.fsrh.org

35. American College of Obstetricians and Gynecologists. Long-Acting Reversible Contraception: Implants and Intrauterine Devices. Practice Bulletin No. 186. Obstet Gynecol. 2017;130(5):e251-e269. doi:10.1097/AOG.0000000000002400

Document Completion: 2025-12-26 Status: PAPER 37 OF 76 COMPLETE Total Length: ~2,600 lines (all 15 sections) Next Paper: #38 - Norgestrel - Racemic gonane progestin

Document Status Update:

• ✅ Section 1: Summary (complete)
• ✅ Section 2: Mechanism of Action (complete)
• ✅ Section 3: Indications and Uses (complete)
• ✅ Section 4: Dosing and Administration (complete)
• ✅ Section 5: Pharmacokinetics and Pharmacodynamics (complete)
• ✅ Section 6: Side Effects and Adverse Reactions (complete)
• ✅ Section 7: Drug Interactions (complete)
• ✅ Section 8: Contraindications and Precautions (complete)
• ✅ Section 9: Special Populations (complete)
• ✅ Section 10: Monitoring and Follow-Up (complete)
• ✅ Section 11: Cost and Accessibility (complete)
• ✅ Section 12: Clinical Evidence and Efficacy (complete)
• ✅ Section 13: Comparison to Alternative Treatments (complete)
• ✅ Section 14: Storage and Handling (complete)
• ✅ Section 15: References (complete)

PAPER 37 (LEVONORGESTREL) NOW COMPLETE - ALL 15 SECTIONS