The effect of carbamazepine on etonogestrel concentrations in contraceptive implant users

作者：Lazorwitz Aaron^*; Davis Anne; Swartz Maryke; Guiahi Maryam

来源：Contraception, 2017, 95(6): 571-577.

DOI：10.1016/j.contraception.2017.03.004

• Contraceptive implant
• Carbamazepine
• Etonogestrel
• Pharmacokinetics
• Contraceptive failure

Objective: The objective was to determine the impact of carbamazepine on the pharmacokinetics and pharmacodynamics of the etonogestrel contraceptive implant.
Study design: We enrolled healthy, reproductive-age women using an etonogestrel implant for 1-3 years. We measured etonogestrel levels at baseline and following 3 weeks of coadministered carbamazepine titrated up to 300 mg twice daily. We also evaluated for ovarian follicle like structures and endometrial thickness using transvaginal ultrasound at the baseline and 3-week visits.
Results: We enrolled 13 women; 10 completed study procedures. Participants' mean age was 25.6 years ( +/- 5.6), mean body mass index was 30.4 (+/- 7.3), and median duration of implant use was 23 months (range 15-35). The median etonogestrel concentrations before and after carbamazepine coadministration were 158.1 pg/mL (range 128-347) and 50.9 pg/mL (range 39-202), respectively (p=.005). In 8 of 10 subjects, the etonogestrel concentration was below the threshold for ovulatory suppression (<90 pg/mL) after carbamazepine coadministration. The number of ovarian follicle-like structures and endometrial thickness did not significantly change before and after carbamazepine coadministration.
Conclusions: Women using a contraceptive implant experienced significant reductions in etonogestrel concentrations following coadministration of 600 mg of carbamazepine. We did not find significant pharmacodynamic changes during this abbreviated follow-up period.

• 出版日期2017-6