Ovarian function during use of vaginal rings delivering three different doses of Nestorone®

A dose-finding, cross-over study to evaluate the effect of a Nestorone®/Estradiol transdermal gel delivery on ovulation suppression in normal ovulating women

“…The progestin on its own was able to adequately block follicle rupture with all doses, but follicular development was sufficiently inhibited only with the two higher ring doses [13].…”

“…NES has been studied extensively in nonoral forms including implants and contraceptive vaginal rings [13,17]. In vitro studies have demonstrated that NES binds selectively to progesterone receptors but does not bind to androgen or estrogen receptors.…”

“…The targeted antiovulatory NES serum threshold was 250 pmol/L, based on data obtained from the above study and a NES-only ring study [12,13]. This formulation was tested in a dose-finding study conducted with the primary objective to establish the minimal dose of NES to ensure ovulation suppression (progesterone levels b 10 nmol/L and no follicle rupture) in 90-95% of the cycles, together with suppressed follicle growth but an E2 dose sufficient to ensure adequate E2 levels (not consistently below 100 pmol/L).…”

Emerging female contraceptives

“…This contraceptive releases 120 µg of etonogestrel and 15 µg of EE/day and is currently approved for use over a 3-week period after which the ring is removed for 1 week, when the user will experience uterine bleeding. An extended regimen of use has been described, with good acceptability and good cycle control; however, this use is currently offlabel [22,23]. Reports suggest that the main reason for women to switch from other contraceptive methods to the CVR (47%) is that this device represents a new, attractive contraceptive method and that, furthermore, > 90% of users were shown to be satisfied with the ring [24].…”

New technologies in contraception

“…9 Nestorone-releasing rings are effective for up to 1 year. 51 In view of the powerful antiovulatory effect of nestorone, twice that of LNG, a phase-1 study was conducted into the potential of the nestorone combined ring for use as emergency contraception in women not at risk of pregnancy. 52 Judging by ultrasound scanning and hormonal profiles, the ring appears to be more effective in disrupting ovulation when given in the follicular phase, and ovulation was absent after the ring had been in situ for 7 days.…”