Nestorone®: Clinical applications for contraception and HRT
The 19-nor derivatives of progesterone are referred to as "pure" progestational molecules as they bind almost exclusively to the progesterone receptor (PR) without interfering with receptors of other steroids. In this category is Nestorone®, which has strong progestational activity and antiovulatory potency with no androgenic or estrogenic activity in vivo. These properties make it highly suitable for use in contraception and hormonal therapy (HT). Due to its high potency, very low doses of Nestorone may be delivered via long-term sustained-release delivery systems. Nestorone, 75 or 100μg per day, released by vaginal ring has suppressed ovulation in women, with inhibition of follicular maturation. A vaginal ring releasing both 150μg of Nestorone and 15μg of ethinyl estradiol per day has effectively suppressed ovulation for 13 consecutive cycles. Nestorone has also been used effectively in a single implant for contraception in breastfeeding women and shows promise for use in transdermal systems as a contraceptive or for HT when combined with estrogen.
Sitruk-Ware, Régine, Margaret Small, Narender Kumar, Yun-yen Tsong, Kalyan Sundaram, and Theodore M. Jackanicz. 2003. "Nestorone®: Clinical applications for contraception and HRT," Steroids 68(10–13): 907–913.
The Nestorone®/Ethinyl Estradiol One-Year Vaginal Contraceptive System