Serum Nestorone and ethinyl estradiol levels, and ovulation inhibition in women using three different dosage combinations of a Nestorone progestogen-ethinyl estradiol contraceptive vaginal ring on a bleeding-signaled regimen.

OBJECTIVES: This trial tested the hypothesis that menstrually signaled use of contraceptive vaginal rings ("rings") releasing low-dose combinations of Nestorone (NES) and ethinyl estradiol (EE) would reliably suppress luteal activity and ovulation, and prevent unintended pregnancy, while controlling the incidence of menstrual bleeding episodes and bleeding days. METHODS: Nestorone/ethinyl estradiol rings releasing 50/10, 50/20 and 150/15 mug/day were studied through 6 months. A ring was to be used continuously, until its removal was signaled by menstrual bleeding. Reinsertion was required 96 h after removal. Serum for NES, EE and progesterone were collected and assayed, and vaginal ultrasound scans were performed in three 5-week periods to examine luteal activity, follicular growth, ovulation and their correlates. In 10 subjects using the 150/15 ring, six samples were drawn in the 24-h period after ring removal to examine serum levels of NES and EE. RESULTS: One hundred sixty subjects at three doses provided blood samples. Median serum concentrations of NES and EE demonstrated dose ratios slightly below the nominal dose ratios expected. Serum NES concentrations declined 19-22% from weeks 3 to 25. Changes in EE levels depended on dose. Nestorone levels fell 81% by 24 h after ring removal and EE levels fell by 50%. Luteal activity was completely suppressed in 94-95% of cycles and in 90% of subjects. Three pregnancies occurred in subjects participating in this serum sampling study. CONCLUSION: Satisfactory serum levels of NES and EE, and a high level of ovulation suppression were achieved. Irregular ring use, however, permitted pregnancies to occur.

Clinical performance and menstrual bleeding patterns with three dosage combinations of a Nestorone progestogen/ethinyl estradiol contraceptive vaginal ring used on a bleeding-signaled regimen.

OBJECTIVE: We examined the clinical performance of contraceptive vaginal rings (rings) delivering Nestorone (NES) progestin and ethinyl estradiol (EE). Ring removal times were signaled by menstrual events. Bleeding patterns, adverse events, patterns of use and continuation rates were the principal parameters evaluated. METHODS: In a two-stage 6-month trial, subjects were randomized to use rings releasing 50 microg/day of NES and either 10 (50/10) or 20 (50/20) microg/day of EE. Subjects were to keep rings continuously in situ until menstrual bleeding or prolonged spotting-signaled removal. Reinsertion was to occur 96 h later. After the randomized stage, an open-label 6-month trial of rings releasing 150 microg/day of NES and 15 microg/day of EE (150/15) began with the same menstrually signaled regimen. RESULTS: Two-hundred forty-six subjects participated in the trial. Six-month pregnancy rates ranged by ring dose from 1.3 to 3.9 per 100. For each ring dose combination, 6-month continuation rates were above 80 per 100. Bleeding and spotting (B+S) days in women with the 50 microg/day NES rings were similar in number to those experienced by cycling women not using contraception. Nevertheless, in the initial 90 days, fewer B+S days were reported by subjects with the 50/20 ring than by subjects with the 50/10 ring (p < .05). Throughout the trial, subjects using the 150/15 ring reported significantly fewer B+S episodes than did subjects with either 50 microg/day NES ring. CONCLUSION: Combined contraceptive rings used with a bleeding-signaled regimen led to few terminations attributed to bleeding problems and to acceptable continuation rates. The 150/15 ring appeared to induce fewer bleeding problems than did the lower-dose NES combination rings, but no important difference in 6-month continuation rates among the three doses was noted.