Elution from intact and broken vaginal contraceptive rings: an in vitro study.

The in vitro elution of the active substances etonogestrel (ETO) and ethinylestradiol (EE) of Ornibel® (a vaginal delivery system) was determined after a deliberate breakage of the vaginal contraceptive ring and compared to the standard elution and hormone release of intact rings under the same experimental conditions. Ornibel® intact and broken vaginal rings were placed in a dissolution buffer and subject to a repetitive sampling of ETO and EE following a standardized in vitro elution (IVE) procedure for 21 days. The hormone dissolution profile was determined by HPLC using a fully validated analytical method. In a second study, rings were broken after day seven, and their elution profiles were compared to that of intact rings. For all utilized batches, the stability conditions established were 24 months at 5°C. Furthermore, no special storage conditions are needed. The instantaneous elution on day 1 of ETO and EE for intact rings were 119±8 µg/day and 15±1 µg/day, respectively (mean ± SD), which was non-significantly different to the immediate release of ETO and EE for broken rings (118±4 µg/day and 14±1 µg/day). The average elution profile for days 2-20 were 132±5 µg/day and 18±1 µg/day (ETO/EE, intact rings) and 132±4 µg/day and 19±1 µg/day (ETO/EE, broken rings) respectively. On day 21, the elution of ETO and EE was numerically similar 111±5 (±4) µg/day and 18±1 µg/day) for both intact and broken rings. The IVE results from intact rings and vaginal rings deliberately cut on day seven similarly did not differ in their release of ETO and EE. Our study concludes that the hormonal release of ETO and EE from Ornibel® are similar for intact and broken vaginal rings under standardized in vitro conditions.