A comparison of cycle control with monophasic levonorgestrel/ ethinylestradiol 100 μg/20 μg versus triphasic norethindrone/ ethinylestradiol 500-750-1000 μg/ 35 μg: A multicenter, randomized, open-label study

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Abstract
Objectives This multicenter, randomized, open-label study was undertaken to compare the effects on menstrual cycle control of two oral contraceptive regimens: monophasic levonorgestrel (LNG) 100 μg/ethinylestradiol (EE) 20 μg (Alesse™ or Loette™) and triphasic norethindrone (NET) 500-750-1000 μg/EE 35 μg (OrthoNovum 7/7/7™). Methods Healthy women with normal menstrual cycles were enrolled and completed up to four cycles of study medication. A total of 384 cycles in the LNG/EE group and 400 cycles in the NET/EE group were evaluable for analysis of cycle control. Results For all treatment cycles, the percentage of cycles classified as normal was consistently higher in the LNG/EE group than in the NET/EE group. By cycle 4, 69.9% of cycles with LNG/EE and 54.4% with NET/EE (p < 0.05) were normal. In individual cycles, consistently lower occurrences of intermenstrual bleeding (total bleeding and/or spotting) were seen for the LNG/EE group, although these differences were not statistically significant. Withdrawal bleeding characteristics were comparable between the two groups, except for the length of the latent period, which was significantly longer in the LNG/EE group. The incidence of treatment-emergent adverse events was similar in the two groups. Conclusion This study indicates that the monophasic LNG/EE 100 μ/20 μ provides better cycle control than the multiphasic NET/EE product, despite its lower EE dose.