What is etonogestrel (a progestin hormone)?

From the Guidelines

Etonogestrel is a synthetic progestin hormone used in various forms of hormonal contraception, primarily as the active ingredient in the subdermal contraceptive implant (Nexplanon/Implanon) and in certain vaginal rings (NuvaRing), providing highly effective contraception with a failure rate of less than 1% 1.

Key Characteristics of Etonogestrel

• It is the active metabolite of the progestin desogestrel.
• The implant is a small, flexible rod placed under the skin of the upper arm, releasing etonogestrel continuously for up to 3 years.
• Etonogestrel works by preventing ovulation, thickening cervical mucus to block sperm, and thinning the uterine lining to prevent implantation.
• Common side effects include irregular bleeding patterns, headaches, mood changes, and breast tenderness.

Clinical Use and Recommendations

• The implant requires insertion and removal by a healthcare provider but offers the advantage of long-term, reversible contraception without requiring daily attention.
• Fertility typically returns quickly after removal of etonogestrel-containing contraceptives.
• The etonogestrel implant is highly effective, with fewer than 1 woman out of 100 becoming pregnant in the first year of use with typical use 1.
• It is suitable for women of all ages, including adolescents, and does not protect against STDs; consistent and correct use of male latex condoms reduces the risk for STDs, including HIV.

Considerations for Use

• Counseling should include information about the effectiveness of different contraceptive methods, the potential for irregular bleeding patterns, and the importance of using a backup method for the first week after insertion.
• The implant can be used by breastfeeding women, with studies generally finding no effects on breastfeeding performance or infant health and growth 1.
• Healthcare providers should prioritize the most recent and highest quality evidence when recommending etonogestrel, considering its effectiveness, safety, and potential side effects 1.

From the FDA Drug Label

NuvaRing (etonogestrel/ethinyl estradiol vaginal ring) is a non-biodegradable, flexible, transparent, colorless to almost colorless, combination contraceptive vaginal ring containing two active components, a progestin, etonogestrel (13-ethyl-17-hydroxy-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-3-one) Etonogestrel is approximately 32% bound to sex hormone-binding globulin (SHBG) and approximately 66% bound to albumin in blood. Receptor binding studies, as well as studies in animals, have shown that etonogestrel, the biologically active metabolite of desogestrel, combines high progestational activity with low intrinsic androgenicity.

Etonogestrel is a progestin, which is a synthetic form of the hormone progesterone. It is the biologically active metabolite of desogestrel and has high progestational activity with low intrinsic androgenicity 2. The molecular weight of etonogestrel is 324.46 2.

From the Research

Definition and Description of Etonogestrel

• Etonogestrel is a type of progestin-only contraceptive implant, which provides long-acting, highly effective reversible contraception 3, 4, 5.
• It is a single rod dispositive that releases etonogestrel, a form of hormonal contraception 4.
• The etonogestrel implant, also known as Implanon, is approved for 3 years of use and has been shown to be safe and effective in preventing unintended pregnancies 5.

Mechanism and Effects

• The etonogestrel implant works by releasing a small amount of etonogestrel into the bloodstream, which prevents ovulation and thickens the cervical mucus to prevent sperm from reaching the egg 4.
• Common side effects of the etonogestrel implant include irregular vaginal bleeding, which can be a reason for premature discontinuation 4, 5.
• The implant has also been shown to improve dysmenorrhea and does not significantly affect bone mineral density, lipid profile, or liver enzymes 5.

Use and Administration

• The etonogestrel implant is inserted subcutaneously by a trained healthcare provider and can be removed at any time 3, 5.
• It is recommended that the implant be inserted by skilled clinicians who provide adequate counseling about its contraceptive effect, benefits, and possible adverse events 4.
• The implant can be used as a "back-up" method for women who desire more effective pregnancy prevention while using combined oral contraceptive pills for its bleeding profile or non-contraceptive benefits 6.