What is the role of hormonal implants in contraception?

Updated: Oct 06, 2020
  • Author: Frances E Casey, MD, MPH; Chief Editor: Richard Scott Lucidi, MD, FACOG  more...
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The US Food and Drug Administration (FDA) approved the contraceptive use of the first levonorgestrel implant (Norplant) in 1990. The Norplant was removed from the market in 2002 due to adverse side effects.  In 2001, a desogestrel based implant (Implanon) was approved and is associated with fewer side effects.   The newest version of the implant (Nexplanon), radiopaque for easier diagnostic testing, was introduced in 2011.  This method consists of a single rod of ethylene vinylacetate copolymer, measuring 40 mm long and 2 mm in diameter and containing 68 mg of etonogestrel. Etonogestrel is a biologically active metabolite of desogestrel. Desogestrel is significantly more potent than levonorgestrel; a serum concentration of 0.09 ng/mL can inhibit ovulation in most women. The implant releases approximately 70 mcg of etonogestrel per 24 hours during the first year of use, achieving peak serum concentrations of 0.7-0.8 ng/mL within the first few weeks. The rate of release decreases to an average of 30 mcg/d in the latter years of use. Contraceptive protection begins within 24 hours of insertion if inserted during the first week of the menstrual cycle. The rod is inserted subcutaneously, usually in the woman's upper arm, where it is visible under the skin and can be easily palpated. [4, 4]

The mechanism of action is a combination of suppression of the LH surge, suppression of ovulation, development of viscous and scant cervical mucus to deter sperm penetration, and prevention of endometrial growth and development.

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