Are the hormone levels the same between Mirena (levonorgestrel) and Nexplanon (etonogestrel)?

Mirena and Nexplanon Contain Different Hormones at Different Levels

No, Mirena and Nexplanon do not contain the same hormone - Mirena contains levonorgestrel while Nexplanon contains etonogestrel, and they are released at different dosage levels. 1, 2

Hormone Types and Differences

• Mirena (IUD):

  • Contains levonorgestrel, a synthetic progestin
  • Available in different formulations:
    • 52 mg levonorgestrel (Mirena) - approved for 5 years
    • 52 mg levonorgestrel (Liletta) - approved for 3 years
    • 13.5 mg levonorgestrel (Skyla) - approved for 3 years 1

• Nexplanon (Implant):

  • Contains etonogestrel, the active metabolite of desogestrel
  • Single-rod implant with 68 mg of etonogestrel
  • Approved for 3 years of use 1, 2

Pharmacological Differences

Etonogestrel (Nexplanon) and levonorgestrel (Mirena) have different pharmacological profiles:

• Etonogestrel:

  • Active metabolite of desogestrel
  • Belongs to the "third-generation" progestins
  • Has weaker androgenic effects compared to levonorgestrel 3, 4

• Levonorgestrel:

  • Belongs to the "second-generation" progestins
  • Has relatively stronger androgenic properties 3, 5

Hormone Release and Effectiveness

• Nexplanon:

  • Failure rate of 0.05% (extremely effective)
  • Releases etonogestrel continuously 2

• Mirena:

  • Failure rate of less than 1% (also highly effective)
  • Releases levonorgestrel locally within the uterus 1, 2

Clinical Implications of Different Hormones

The different hormones can lead to different side effect profiles:

• Bleeding patterns:

  • Mirena: May cause irregular bleeding initially, but often leads to lighter periods or amenorrhea over time 1
  • Nexplanon: More commonly associated with unpredictable bleeding patterns, which is the most common reason for discontinuation 1, 2

• Hormone-specific considerations:

  • Drug interactions may differ between the two products
  • For example, certain antiretroviral medications like efavirenz may reduce the effectiveness of both methods, but potentially through different mechanisms 1, 2

Important Clinical Considerations

• Both are highly effective long-acting reversible contraceptives (LARCs) with failure rates less than 1% 2

• The choice between Mirena and Nexplanon should consider:

  • Patient preference for IUD vs. implant
  • Desired duration of contraception (3 vs. 5 years)
  • Medical conditions that might favor one hormone over another
  • Previous experience with hormonal contraceptives

• For patients with certain medical conditions, the difference in hormones may be clinically significant:

  • Patients with hereditary angioedema may tolerate etonogestrel (Nexplanon) differently than levonorgestrel (Mirena) 1
  • Patients on certain medications may experience different drug interactions with each hormone

Understanding these differences is crucial for providing appropriate contraceptive counseling and ensuring optimal outcomes for patients seeking long-term contraception.