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

Abstract

Objectives: To compare the bleeding patterns and cycle control of an oral contraceptive (OC) containing ethinylestradiol (EE) 30 μg/drospirenone (drsp) 3mg administered in a 21/7 regimen versus a lower-dose OC containing EE 20 μg/drsp 3mg administered in a 24/4 regimen, using data from two identically designed studies.

Materials and methods: In the first study, 326 healthy women (18-35 years) received EE 30 μg/drsp 3mg in a 21/7 regimen. In the second study, 1027 healthy women (17-36 years) received EE 20 μg/drsp 3mg in a 24/4 regimen. Participants recorded bleeding using daily completed diaries over 13 treatment cycles.

Results: During cycles 1-12, the prevalence of scheduled withdrawal bleeding was lower with EE 20 μg/drsp 3mg 24/4 than with EE 30 μg/drsp 3mg 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 3mg 24/4 than with EE 30 μg/drsp 3mg 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 3mg 24/4 recipients and 3.8-7.9% of EE 30 μg/drsp 3mg 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 3mg 24/4 versus 3.2 episodes with EE 30 μg/drsp 3mg 21/7).

Conclusions: A low-dose 24/4 regimen OC containing EE 20 μg/drsp 3mg is generally comparable in terms of bleeding to a higher-dose 21/7 regimen OC containing EE30 μg/drsp 3mg. Between-treatment differences in bleeding intensity and unscheduled intracyclic bleeding rates were observed.