Population Council Research that makes a difference

The contraceptive vaginal ring.

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 release 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 soft and flexible and easily inserted into the vagina by the woman herself. Once in place, the ring inhibits ovulation by continuously releasing a low dose of hormones through the vaginal walls and then into the bloodstream.

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 concentrations of steroids that a woman’s liver is exposed to through repetitive, once-a-day oral administration of hormones.

Preliminary research results suggest that the ring is as effective as oral contraceptives in preventing pregnancy when used as directed. The results also suggest that the ring is well-liked and well-accepted by women and their partners.

The Phase 3 trial of the CVR enrolled 2,277 women in two separate pivotal safety and efficacy trials. The data collected currently are being analyzed. One of the trials included 12 international centers and was conducted by the Population Council in Europe, Australia, Latin America, and the United States in collaboration with the World Health Organization and with funding from the US Agency for International Development. This trial also included an acceptability substudy funded by the National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH). Participants were interviewed and the data collected using a Council-developed application, audio computer-assisted self-interviewing (ACASI), a method that can increase accuracy in reporting and the speed with which data become available. The NICHD, NIH conducted the other pivotal trial at 15 additional sites across the United States in conjunction with its Contraceptive Clinical Trials Network.