Options might expand with vaginal rings

The options in birth control might be set to expand: Watson Pharmaceuticals of Corona, CA, has signed an exclusive licensing agreement to commercialize the Population Council's investigational contraceptive vaginal ring in the United States, Canada, and Mexico. The ring, which contains ethinyl estradiol and a new progestin, Nestorone, is in Phase 3 clinical development.

The Nestorone/ethinyl estradiol contraceptive vaginal ring is designed to simultaneously release Nestorone along with a low dose of ethinyl estradiol for up to 13 cycles. The ring remains in the vagina for three weeks per cycle, followed by one ring-free week. Early research indicates the device, used on a 21-day-in and seven-day-out regimen, provides women safe and effective contraception.1

The ring, if approved by the Food and Drug Administration, will provide women with an important new user-controlled long-term contraceptive method, says Peter Donaldson, PhD, president of the Population Council in New York City.

In signing the agreement with the Population Council, Watson Pharmaceuticals will be responsible for future development, regulatory, and marketing expenses related to the commercialization of the contraceptive ring. In addition, the company will allow product discounts on the ring for qualified public health agencies should the device receive regulatory approval, says Patty Eisenhaur, a Watson Pharmaceuticals spokesperson.

Focus on new progestin

Many of the contraceptive options under development by the Population Council contain Nestorone, a synthetic progestin similar to the natural hormone progesterone. About 2¼ inches in diameter, the contraceptive ring in development is a thin, flexible drug-delivery system that fits into the vagina and can be inserted easily by the patient. Once in place, the ring slowly releases hormones that are absorbed into the bloodstream.

The Phase 3 study of the ring was conducted at 27 locations throughout the United States, Latin America, Europe, and Australia. Women in the study were healthy, ages 18-40, and were seeking contraception. The study enrolled 2,277 women and was completed in June 2009. Results have not yet been published.

According to the Population Council, preliminary results indicate the efficacy and safety of the ring appear to be comparable to that of other marketed hormonal methods. Preliminary acceptability data indicate that most women in the trial are satisfied with the contraceptive method and find it easy to use, the council states.

Population Council scientists also are looking at use of Nestorone in a transdermal gel. Scientists have completed a dose-finding, open-label, cross-over study to evaluate the effect of the transdermal gel on ovulation suppression in normal women of fertile age. Antares Pharma of Ewing, NJ, and the Population Council are partners in developing the transdermal gel.

Nestorone also is being eyed for use in a spray-on contraceptive; Acrux, a Melbourne, Australia, pharmaceutical company, has partnered with the Population Council to develop the novel birth control method. Acrux and the Population Council began working together in 2003, combining Acrux's Metered Dose Transdermal System (MDTS) technology to deliver Nestorone to the skin. MDTS is a hand-held aerosol drug delivery system. The spray, delivered via MDTS, would be painless, easy to use, and convenient for women.

Vaginal rings, topical gels, and sprays all offer the benefit of being entirely under the user's control. They are convenient to use and easy to discontinue when the woman wishes to restore her fertility, according to the council.

Scientific exploration of Nestorone is not being limited to women. The Population Council is collaborating with the National Institutes of Health to examine a transdermal gel containing Nestorone, combined with testosterone gel, for male contraception. A clinical trial is under way to determine effective doses of the hormones to decrease sperm production.

The Population Council is familiar with vaginal technology. It has developed two vaginal rings that release natural progesterone: one for contraception during lactation trademarked as Progering, and one for hormone supplementation and pregnancy maintenance during in vitro fertilization known as Fertiring. Both rings are approved and licensed for distribution in Bolivia, Chile, Ecuador, and Peru.

The Population Council plans a large Phase 3 clinical trial in India for the contraceptive progesterone ring in women who are breastfeeding and need to space births. The trial will compare the efficacy and safety of the ring with that of a Copper T 380A intrauterine device.


  1. Sivin I, Mishell DR Jr., Alvarez F, et al. Contraceptive vaginal rings releasing Nestorone and ethinyl estradiol: A 1-year dose-finding trial. Contraception 2005; 71:122-129.