A multicenter, randomized comparative trial of the clinical effects on cycle control of two 21-day regimens of oral contraceptives containing 20 µg EE.
Purpose: This multicenter, randomized, open-label comparative study was designed to evaluate the effects on cycle control of the only two oral contraceptives (OCs) containing 20 µg ethinyl estradiol (EE) that are available in North America.Methods: Women of childbearing age who desired OCs for birth control were eligible to enroll in this study. Sixty-two subjects were randomly assigned to receive Alesse (levonorgestrel 0.1 mg and EE 20 µg) or Loestrin Fe 1/20(R) (norethindrone acetate 1.0 mg and EE 20 µg).Results: At the time of the interim analysis data cut-off 32 subjects had completed 3 cycles of Alesse and 30 had completed 3 cycles of Loestrin Fe 1/20. The groups were similar with regard to age, weight, height, race, and prior OC usage. A total of 22% of the subjects in the levonorgestrel group and 27% of those subjects in the norethindrone group had never used OCs. The remainder had not used OCs for at least 3 months before entering the trial. During the third cycle of use, the percentage of normal cycles was significantly greater in the levonorgestrel group (P <.05). Moreover, the rate of intermenstrual bleeding (breakthrough bleeding and/or spotting) in the norethindrone group (62.9%) was more than double that in the levonoregestrel group (29.0%). Cumulatively, from cycles 1 to 3, there was a higher incidence of absence of withdrawal bleeding with norethindrone when compared with levonorgestrel (27.7% vs 5.3%).Conclusion: The results of this study demonstrate that good cycle control can be achieved with an OC containing 20 µg EE. The superior cycle control of Alesse compared with Loestrin Fe 1/20 is consistent with that found in comparative studies of the cycle control of levonorgestrel, norethindrone, and norethindrone acetate containing OCs that had a higher dose of EE.
Del Conte A
Wyeth-Ayerst Research, Pennsylvania, Philadelphia, USA
Loffer
F
Grubb
G