New contraceptive ring now in advanced trials
When you prescribe the contraceptive vaginal ring (NuvaRing, Organon; West Orange, NJ), you instruct the patient that the ring is worn for three weeks, then is removed for a one-week ring-free period. When the ring-free period is completed, a new ring must be used. But what if there was a ring that could be used for more than a three-week period?
The Population Council is testing the safety and efficacy of a longer-lasting contraceptive vaginal ring. Two investigations involving 2,200 women at 22 sites on four continents are being conducted prior to application to the Food and Drug Administration (FDA) for market approval. The Population Council is conducting one trial at 10 international sites in collaboration with the World Health Organization, with funding from the U.S. Agency for International Development. It also is working with the National Institutes of Health's National Institute of Child Health and Human Development in conducting a similar study at additional sites across the United States. U.S. organizations participating in the trials include: California Family Health Council, California Women and Children's Hospital, Columbia University, Contraceptive Research and Programs, Jones Institute of Reproductive Medicine, MacDonald Physicians, Magee-Womens Hospital, New York University Medical Center Family Planning Division, Oregon Health Sciences University, San Francisco General Hospital, University of Chicago Hospital, University of Cincinnati College of Medicine, University of Colorado, University of Pennsylvania Medical Center, and University of Texas Southwestern Medical Center.
The ring is formulated with the Population Council's proprietary progestin, Nestorone, and a low dose of ethinyl estradiol, says Diane Rubino, council spokeswoman. Study participants are instructed to keep the contraceptive ring in place for three weeks, and then remove it for one week to permit periodic bleeding. Seven days later, the device is to be reinserted. The ring is designed for use for one full year, which is seen as a "clear advantage" by Ruth Merkatz, RN, PhD, the council's director of clinical development. "This means convenience for women; they will not need to return frequently to obtain multiple prescriptions," she notes. "This is especially important when access to health care is a problem, which affects many women in the U.S. and worldwide."
The contraceptive vaginal ring represents a method that is under the woman's control and requires a minimum of attention from medical personnel, states Merkatz. "Unlike the pill that women must remember to take every day, or devices that women must use with every act of intercourse to prevent pregnancy, the woman leaves [the ring] in for three weeks every month and leaves it out for one week," she notes.
Review the research
Nestorone and trimegestone are the most potent progestins synthesized to date, followed by two of the older progestins, keto-desogestrel and levonorgestrel.1 The Nestorone vaginal ring is a thin, flexible product made of silicone rubber. The ring inhibits ovulation by continuously releasing a low dose of hormones through the vaginal walls and into the bloodstream. In a multicenter one-year dose-finding trial that looked at three dose combinations of Nestorone and ethinyl estradiol in a ring delivery system, results indicate that the studied formulations, used on a 21-days-in, seven-days-out regimen, provided women safe and effective contraception.2
Previous research suggests that the ring is safe for use. Results from a 2006 study indicate that a Nestorone contraceptive vaginal ring should be as safe as a combined oral contraceptive when it comes to thrombosis risk.3
In studies to date, the Nestorone ring has been shown to be highly effective in inhibiting ovulation and preventing pregnancy, says Merkatz. The large Phase 3 studies will provide more information on efficacy, as well as safety, she states.
Draw the circle wide
The Nestorone studies now under way are designed to include smokers and overweight women in the study populations, two groups that typically have been excluded in studies of hormonal contraception. This inclusive testing model is designed to provide a more comprehensive assessment of the risks and benefits of using the one-year ring, say Population Council officials.
During the study, Population Council researchers will conduct interviews to further assess the method's acceptability among trial participants. An independent data safety monitoring board will review safety and efficacy information on a regular basis. Trials will close in mid-2009.
When could a Nestorone ring be available? If testing indicates that the product is successful and the FDA approves the contraceptive, a one-year ring could be approved for use in about five years, estimate Population Council officials.
Robert Hatcher, MD, MPH, professor of gynecology and obstetrics at Emory University School of Medicine in Atlanta, says he would like to see research on the ring in different regimens."It is unfortunate that this exciting new ring isn't evaluating a better approach than 21/7; I would rather see use in 24/4 or 25/3," Hatcher remarks. "I definitely would like to see an arm evaluate continuous use of the ring."
References
- Sitruk-Ware R. New progestagens for contraceptive use. Hum Reprod Update 2006; 12:169-178.
- 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.
- Rad M, Kluft C, Menard J, et al. Comparative effects of a contraceptive vaginal ring delivering a nonandrogenic progestin and continuous ethinyl estradiol and a combined oral contraceptive containing levonorgestrel on hemostasis variables. Am J Obstet Gynecol 2006; 195:72-77.
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