Objective: To compare the cycle control, efficacy, and safety of a new low-dose combined oral contraceptive containing ethinylestradiol 20mug and drospirenone 3mg with an established formulation containing ethinylestradiol 20mug and desogestrel 150mug.

Methods: This was a randomized, open-label, parallel-group, multicenter study of healthy women (aged 18-35 years) over seven treatment cycles. Both combined oral contraceptives were administered once daily for 21 consecutive days followed by a 7-day hormone-free interval.

Results: A total of 445 women were randomized to treatment; of these, 441 (ethinylestradiol 20mug/drospirenone 3mg, n = 220; ethinylestradiol 20mug/desogestrel 150mug, n = 221) went on to receive study medication. There was a trend towards reduced intracyclic bleeding with continued treatment in both treatment groups, consistent with clinical experience. Intracyclic bleeding was highest during the first treatment cycle in both treatment groups, but was generally much lower in subsequent cycles. More than 90% of women in each of the groups experienced withdrawal bleeding during the study. The duration of withdrawal bleeding remained fairly constant throughout the study. The maximum intensity was mainly bleeding, rather than spotting. Overall, cycle control, efficacy, and safety profiles were comparable between both groups. Adverse events were generally of mild-to-moderate intensity and were those typical of hormonal contraceptive use.

Conclusion: In conclusion, both ethinylestradiol 20mug/drospirenone 3mg and ethinylestradiol 20mug/desogestrel 150mug are effective and well tolerated contraceptives that provide good cycle control.