Comparison of efficacy, cycle control, and tolerability of two low-dose oral contraceptives in a multicenter clinical study.Contraception. 1999 Nov; 60(5):269-74.C
This study compares the contraceptive reliability, cycle control, and tolerability of two oral contraceptive preparations containing 20 micrograms of ethinyl estradiol combined with either 75 micrograms of gestodene (EE/GSD) or 150 micrograms of desogestrel (EE/DSG). Women received the trial preparations daily for 21 days, followed by a 7-day pill-free interval. Contraceptive efficacy, cycle control, and tolerability were evaluated over a period of 12 cycles. Efficacy data of 14,700 treatment cycles (EE/GSD: 7299; EE/DSG: 7401) were obtained from 1476 women (EE/GSD, n = 740; EE/DSG, n = 736). Both preparations provided effective contraception and good cycle control with a similarly low incidence of both spotting and breakthrough bleeding. The spotting rates in both treatment groups decreased from 35.1% (EE/GSD) and 37.5% (EE/DSG) in the first treatment cycle to approximately 10% in the fourth treatment cycle. The spotting incidence as percent of the total number of cycles was 12.7% for EE/GSD and 14.3% for EE/DSG. The breakthrough bleeding incidence was 5.2% of all cycles for EE/GSD and 6.0% of all cycles for EE/DSG. For 84.7% of the cycles in the gestodene group and for 82.5% of the cycles in the desogestrel group, neither spotting nor breakthrough bleeding were recorded. Overall, the spotting and breakthrough bleeding incidence tended to be lower with EE/GSD than with EE/DSG. However, the difference was not statistically significant. Amenorrhea was recorded in 2.7% of the cycles with EE/GSD and in 2.9% with EE/DSG. Both preparations were well tolerated and showed a similar pattern of adverse events. More than 83% of the women in both groups either did not gain weight or lost more than 2 kg. Both preparations had a beneficial effect on dysmenorrhea. Both regimens provided reliable contraception and good cycle control. The incidence of adverse events was relatively low and both preparations were well tolerated.