A historical cycle control comparison of two drospirenone-containing combined oral contraceptives: ethinylestradiol 30 μg/drospirenone 3 mg administered in a 21/7 regimen versus ethinylestradiol 20 μg/drospirenone 3 mg administered in a 24/4 regimen

ObjectivesTo compare the bleeding patterns and cycle control of an oral contraceptive (OC) containing ethinylestradiol (EE) 30 μg/drospirenone (drsp) 3 mg administered in a 21/7 regimen versus a lower-dose OC containing EE 20 μg/drsp 3 mg administered in a 24/4 regimen, using data from two identically designed studies.Materials and methodsIn the first study, 326 healthy women (18–35 years) received EE 30 μg/drsp 3 mg in a 21/7 regimen. In the second study, 1027 healthy women (17–36 years) received EE 20 μg/drsp 3 mg in a 24/4 regimen. Participants recorded bleeding using daily completed diaries over 13 treatment cycles.ResultsDuring cycles 1–12, the prevalence of scheduled withdrawal bleeding was lower with EE 20 μg/drsp 3 mg 24/4 than with EE 30 μg/drsp 3 mg 21/7 (82.0–91.7% versus 94.8–100.0% of women, respectively); moreover, a higher proportion of women reported a maximum intensity of light scheduled withdrawal bleeding with EE 20 μg/drsp 3 mg 24/4 than with EE 30 μg/drsp 3 mg 21/7 (30.9–39.0% versus 13.8–20.5% of women, respectively). In cycles 2–13, unscheduled intracyclic bleeding was reported by 7.7–13.8% of EE 20 μg/drsp 3 mg 24/4 recipients and 3.8–7.9% of EE 30 μg/drsp 3 mg 21/7 recipients; these were mainly single bleeding days. During reference periods 1–4, the mean number of bleeding episodes was similar between groups (3.1–3.3 episodes with EE 20 μg/drsp 3 mg 24/4 versus 3.2 episodes with EE 30 μg/drsp 3 mg 21/7).ConclusionsA low-dose 24/4 regimen OC containing EE 20 μg/drsp 3 mg is generally comparable in terms of bleeding to a higher-dose 21/7 regimen OC containing EE 30 μg/drsp 3 mg. Between-treatment differences in bleeding intensity and unscheduled intracyclic bleeding rates were observed.