Women and men in developing and industrialized nations continue to seek additional long-term, convenient, user-controlled contraceptives To address this need, scientists at the Population Council have developed contraceptive vaginal rings that deliver synthetic hormones and can provide a number of advantages compared to currently available methods of hormonal contraception.

One such contraceptive vaginal ring (CVR) contains ethinyl estradiol (EE), an approved, marketed hormonal product, and Nestorone® (NES), an investigational new chemical entity. NES is a potent progesterone derivative that is not active orally, but is effective when non-oral routes are used, such as vaginal rings, implants, and transdermal systems. This CVR provides a steady release rate of hormones without requiring daily administration to produce the desired contraceptive effect and maintain regular menstrual cycles.

Roughly 2-1/4 inches in diameter, the ring is thin and flexible and easily inserted into the vagina by the woman herself. Once in place, the ring slowly releases hormones that are absorbed into the bloodstream.

A major advantage of this CVR is that it can be used for one year, resulting in a number of benefits over existing methods including enhanced convenience. Because this CVR does not require daily oral intake of hormones, the overall amount of steroids administered over 21 days is lower than the daily high concentrations of steroids that a woman’s liver is exposed to when there is repetitive, once-a-day oral administration of hormones for 21 days. After insertion of the ring into the vagina, the hormones are rapidly absorbed by the tissue in the vagina. The hormones then pass into the general circulation and a steady state is achieved by about the fifth day of use. This action prevents ovulation to provide the contraceptive benefit.

With support from the US Agency for International Development, the World Health Organization, and in collaboration with the National Institutes of Health, the Population Council has been conducting a Phase 3, multicenter clinical trial to evaluate the efficacy, safety, and acceptability of this one-year CVR. Menstrual cycle control, bleeding patterns, and side effects are also being evaluated. Women follow a 21-day, continuous ring use schedule, followed by one week without the ring inserted.

The Phase 3 study is being conducted at 27 locations throughout the United States, Latin America, Europe, and Australia. Women in the study are healthy, aged 18–40, and seeking contraception. Nearly 2,300 women have been enrolled into the study, which will complete by June 2009.

Preliminary results have demonstrated that the efficacy and safety of the CVR appear to be comparable to other marketed hormonal methods, and bleeding control is excellent. The current acceptability data indicate that most women are very satisfied with this contraceptive method and find it easy to use.

Locations

27 locations throughout the United States, Latin America, Europe and Australia

Duration

September 2005–June 2009

Publications/Resources on this project

Related Projects

See Also

• Female Contraceptives

• International Committee for Contraception Research

• Product Research and Development