Contraceptive efficacy and tolerability of ethinylestradiol 20 µg/drospirenone 3 mg in a flexible extended regimen: an open-label, multicentre, randomised, controlled study

Abstract

Background The contraceptive efficacy and tolerability of a new flexible extended regimen of ethinylestradiol (EE) 20 μg/drospirenone (DRSP) 3 mg to extend the menstrual cycle and enable management of intracyclic (breakthrough) bleeding (flexible_MIB) was investigated and the bleeding pattern compared with a conventional 28-day regimen and a fixed extended 124-day regimen. Study design This Phase III, 2-year, multicentre, open-label study randomly (4:1:1) allocated women (aged 18–35 years) to the following regimens: flexible_MIB (24–120 days' active hormonal intake with 4-day tablet-free intervals); conventional (24 days' active hormonal intake followed by a 4-day hormone-free interval); or fixed extended (120 days' uninterrupted active hormonal intake followed by a 4-day tablet-free interval). Primary outcomes included the number of bleeding/spotting days during Year 1 (all regimens) and the number of observed unintended pregnancies over 2 years (flexible_MIB only). Results Results were analysed in 1067 women (full analysis set). The mean number of bleeding/spotting days was lower with the flexible_MIB vs the conventional regimen [41.0±29.1 (95% CI 38.8–43.3) vs 65.8±27.0 (95% CI 62.2–69.4) days, pMIB regimen was 0.64 (95% CI 0.28–1.26). All regimens had comparable tolerability profiles. Conclusions EE 20 μg/DRSP 3 mg administered as a flexible extended regimen with MIB is effective, well tolerated and is associated with statistically significantly fewer bleeding/spotting days and fewer withdrawal bleeding episodes vs EE/DRSP in a conventional 28-day regimen. The flexible_MIB also provided statistically significantly fewer spotting days vs EE/DRSP in a fixed extended 124-day regimen (post hoc evaluation). The flexible_MIB regimen allows women to extend their menstrual cycle and manage their intracyclic (breakthrough) bleeding.