Vaginal Ring Dose-Finding Results Published
Contraceptive vaginal rings (CVRs) offer women a self-controlled, non-daily delivery system. One CVR – the FDA approved NuvaRing® – is on the market, and another, the one-year Nestorone® ring, has completed Phase III clinical trials. Both contain ethinyl estradiol (EE). When delivered vaginally, EE results in substantial hepatic induction of clotting factors, meaning a vaginal ring that employs EE offers no safety advantage over an oral contraceptive. However, 17β-estradiol (E2) does not cause hepatic induction of clotting factors when delivered vaginally. A vaginal ring that uses E2 for its estradiol component could provide a safe, effective contraceptive for women at high risk for thrombosis, such as women who are obese.
Therefore, researchers have sought to create a vaginal ring that utilizes E2 rather than EE as the estrogen component. Results from a dose-finding study on this novel vaginal ring, led by researchers from the Oregon Health & Science University and the Population Council, were published in the May issue of Contraception. The study looked at three different doses of E2; none of the dosages consistently released high enough levels of estradiol. The researchers note, however, that studies of vaginal rings containing higher levels of E2 are already underway.