Subdermal Implants Three progestin-releasing subdermal implants systems are in use worldwide: Jadelle™, Sino-Implant II™, and Implanon™. All three offer long-acting contraception that requires no continuing action by the user and are, hence, forgettable. All are very highly effective and have no serious risk. Each can produce irregular bleeding, which is the principal reason for discontinuation. The mechanism of action is suppression of ovulation in the initial years of use, plus thickening of the cervical mucus that prevents sperm penetration.
The original levonorgestrel implant (Norplant™) six-rod system was replaced with a two-rod version (Jadelle™), which is identical in its release rate and clinical activity to Norplant™ and is easier to insert and remove (250). Jadelle™ is widely used around the world. It is approved by the FDA but is not marketed in the United States. It is approved for 5 years. The Sino-Implant II™ is a less expensive two-rod levonorgestrel system manufactured in China and available in several countries. It is effective for 4 years (251). Implanon™ is the only subdermal implant sold in the United States. It is a single rod system containing etonogestrel, the active metabolite of desogestrel. Because of the greater potency of etonogestrel, the single rod releases enough to completely inhibit ovulation for at least 3 years. The single-rod system is most easily inserted and removed. In a United States trial, mean time for insertion was only a half minute and removal required a mean time of 3.5 minutes (252).
A systematic review of 29,972 women and 28,108 woman-months of follow-up with Norplant™, Jadelle™, or Implanon™ found no differences in pregnancies or continuation rate over 4 years. No pregnancies occurred in any of the trials. There were no differences in side effects or adverse events. The most common side effect was unpredictable vaginal bleeding (253).
In 923 women followed for 20,648 treatment cycles in 11 studies there were no pregnancies with Implanon™ in place. Six pregnancies occurred within 14 days of removal of the devices. When these are included, as required by FDA, the cumulative Pearl index was 0.38 pregnancies per 100 woman-years at 3 years (254). Irregular bleeding was a problem, but occurred most frequently in the first 90 days of use and decreased over time. In a randomized comparison with the six-rod Norplant™, Implanon™ users had less frequent vaginal bleeding, but more became amenorrheic (255). Other commonly reported side effects are headache, weight gain, acne, breast tenderness, and emotional lability (254). Only 2.3% of subjects discontinued because of weight gain. Most women can use Implanon™. The US MEC lists only a small number of conditions as category 3, and these are based on theoretical concerns without actual evidence of harm (7). Insertion in the immediate postpartum period appears to have no adverse effects on mother or infant (256).
Bone density is not affected by Implanon™, probably because ovarian follicular activity is not totally suppressed and estradiol synthesis continues (257). Enlarged follicular ovarian cysts are common during the first year of use of Jadelle™or Implanon™ and usually resolve spontaneously (258).