Comparison of uterine concentrations of ethinyl estradiol and etonogestrel after use of a contraceptive vaginal ring and an oral contraceptive.

OBJECTIVE

To compare uterine tissue concentrations of ethinyl estradiol (EE) and etonogestrel (ENG) after one cycle of use of a contraceptive vaginal ring (NuvaRing; NV Organon, Oss, The Netherlands) or a combined oral contraceptive (COC).

DESIGN

Randomized, open-label, pharmacokinetic study.

SETTING

Obstetrics and gynecology unit.

PATIENT(S): Eight premenopausal women about to undergo hysterectomy but otherwise healthy.

INTERVENTION(S): One cycle (17-21 days) of NuvaRing or COC treatment that ended with surgical hysterectomy.

MAIN OUTCOME MEASURE(S): Tissue concentrations of EE and ENG in uterine tissue samples taken from the upper myometrium and mid-myometrium, the cervical region, and the endometrium.

RESULT(S): In both groups, concentrations of EE and ENG were similar in uterine tissue taken from the upper myometrium and mid-myometrium and the cervical region. However, compared with the COC group, concentrations of both hormones were markedly lower in tissue samples from the endometrium of women who had been treated with NuvaRing.

CONCLUSION(S): Vaginal administration of hormones with NuvaRing did not produce elevated uterine concentrations of EE and ENG, compared with an oral contraceptive.