Delivery of progestins via the subdermal versus the intrauterine route: comparison of the pharmacology and clinical outcomes

ABSTRACT

Introduction: Subdermal and intrauterine progestin releasing systems are two types of long-acting reversible contraceptive systems (LARC). Their use has transformed current contraceptive practice management. There is not much objective evidence to help decide which method is preferable and in which particular circumstance using objective criteria.

Areas covered: MEDLINE, POPLINE, PubMed, and clinicaltrials.gov were searched using the terms “implant” vs “IUS” and then adding the terms “levonorgestrel” and “etonogestrel” to the implant arm and “levonorgestrel” to the IUS arm. This was done using commercial names as well for the terms “pharmacodynamics” and “pharmacokinetics” as well as for the term “therapeutic.”

Preference was given to comparative studies of the highest degree.

Expert opinion: Under normal circumstances, user satisfaction appeared marginally greater for intrauterine rather than subdermal progestin provision. However, after uterine events such as pregnancy or surgical evacuation of the uterus, implants performed better. Intrauterine progestin is preferable for therapeutic purposes.

KEYWORDS:

• Progestin
• subdermal implant
• hormone-releasing IUS
• LARC
• therapeutic
• levonorgestrel
• etonogestrel

Article Highlights

• Significance of pharmacokinetic differences between subdermal implants and LNG-IUSs

• Significance of pharmacodynamic differences between subdermal implants and LNG-IUSs

• Subdermal implants are vulnerable to failure when they do not inhibit ovulation even though they exert pharmacological actions elsewhere

• LNG-IUSs act mainly locally and the serum LNG levels which they produce, while pharmacologically active constitute a “spill” phenomenon.

• Randomized controlled trials and cohort studies tend to favor LNG-IUSs over subdermal implants

• When there is uterine involvement e.g. Postpartum or postabortum, then studies favor subdermal implants over LNG-IUSs

• Only intrauterine LNG can be supplied in sufficiently high doses to be therapeutic in many gynecological conditions

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Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer declaration of interest

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose

Additional information

Funding

This paper was not funded