Implanon and Bleeding
Some facts about Implanon, the progestin-only [68 mg etonogestrel (3-keto-desogestrel)] single-rod implant device:
1. The contraceptive effect of Implanon is established within 24 hours after insertion; ovulation and fertility return within 1 month after the implant is removed.
2. The timing of insertion of Implanon is based on the patient’s menstrual cycle and current contraceptive method:
* For a woman who is not using a hormonal contraceptive, insertion should take place during the first 5 days of menses.
* For a woman who is actively using a cyclic hormonal contraceptive, the device should be inserted during the hormone-free interval.
* For a woman on a continuous hormonal contraceptive, Implanon can be inserted at any time.
* After pregnancy, the device can be inserted 3 or 4 weeks after delivery.
The Implanon rod can be removed at any time. It must be removed after 3 years of use.
The Implanon rod was originally studied in women who weighed no more than 130% of their ideal body weight. The effectiveness of Implanon in obese women has not been thoroughly assessed in a large population study.
3. Implanon is not associated with loss of bone mineral density (BMD).
What is the major side effect of Implanon?
Frequent or unpredictable bleeding (or both) is the major side effect of Implanon.
In one study of 324 women who used Implanon, continuation rates were 75%, 59%, and 47% at 1 year, 2 years, and 2 years-9 months, respectively. Of women who discontinued Implanon, 91% did so because of frequent or unpredictable bleeding or both. In another study, the continuation rate was 66% at 1 year.
Why the unpredictable bleeding?
Women using Implanon who have higher circulating estradiol levels and ovarian follicle activity may be at greater risk of abnormal patterns of bleeding.
Women using progestin contraceptives who have abnormal uterine bleeding have elevated levels of endometrial enzymes, such as matrix metalloproteinases and neutrophil elastase, that prevent epithelial tissue repair.
A possible solution
In a preliminary report, women with prolonged bleeding in association with Implanon were randomized to various treatment regimens, among which were doxycycline, 100 mg twice daily for 5 days, or placebo. Doxycycline treatment significantly reduced prolonged bleeding compared with placebo (4.8 days [95% confidence interval (CI), 3.9 to 5.8 days] versus 7.5 days [95% CI, 6.1 to 9.1 days], respectively).
Doxycycline may inhibit these [endometrial] enzyme systems and enhance repair of endometrial epithelial tissue. Whether doxycycline will become a widely used treatment for prolonged bleeding associated with Implanon remains to be determined in additional clinical trials.