Multicenter, comparative study of cycle control, efficacy and tolerabilityof two low-dose oral contraceptives containing 20 mu g ethinylestradiol/100 mu g levonorgestrel and 20 mu g ethinylestradiol/500 mu g norethisterone

A comparison of cycle control, efficacy and tolerability of two oral contra ceptive preparations containing 20 mug ethinylestradiol combined with eithe r 100 mug levonorgestrel (EE/LNG 20/100) or 500 mug norethisterone (EE/NET 20/500) was conducted. These results were compared to a standard reference preparation, containing 30 mug ethinylestradiol combined with 150 mug levon orgestrel (EE/LNG 30/150). Efficacy data from 8,544 treatment cycles were o btained from 767 women. Good cycle control and effective contraception was achieved with the two LNG preparations, however, the cycle control results were less favorable with EE/NET 20/500. The cumulative incidence of women w ith at least one episode of intermenstrual bleeding from cycles 2 to 7 (pri mary target variable) was 43.9% for EE/LNG 20/100, 72.7% for EE/NET 20/500, and 15.7% for the standard EE/LNG 30/150. The difference between the 2 20 mug of EE preparations, which favored EE/LNG 20/100, was statistically sign ificant (p = 0.001). The overall spotting rates (cycles 1-13) were 9.3% for EE/LNG 20/100,21.7% for EE/NET 20/500, and 3.3% for the standard EE/LNG 30 /150. Amenorrhea was reported in 7.1% (EE/LNG 20/100),20.6% (EE/NET 20/500) , and 0.9% (standard EE/LNG 30/150), respectively. Intermenstrual bleeding episodes were shorter with EE/LNG 20/100 and EE/LNG 30/150 of the 13 treatm ent cycles. The study Pearl indices were 0.9 for EE/LNG 20/100, 1.9 for EE/ NET 20/500, and 0.0 for EE/LNG 30/150. All three treatments were well toler ated. However, tolerability was somewhat less favorable with EE/NET 20/500. A total of 160 women prematurely discontinued the study for various reason s (EE/LNG 20/100:7%; EE/NET 20/500: 18%; EE/LNG 30/150:4%). The overall adv erse event incidence rate during the trial was low in all groups. Blood pre ssure remained largely unaffected. Thirteen serious adverse events were rec orded for all treatment groups, all but one were assessed as not related to the treatments. There were no remarkable treatment related differences in mean body weight throughout the study and the laboratory values were largel y unaffected in all three treatments groups. (C) 2001 Elsevier Science Inc. All rights reserved.