The efficacy and safety of a low-dose, 91-day, extended-regimen oral contraceptive with continuous ethinyl estradiol.

Background: This clinical trial was conducted to demonstrate the efficacy and safety of a 91-day extended-regimen, low-dose combination oral contraceptive (OC) consisting of 84 days of ethinyl estradiol (EE) 20 mcg/levonorgestrel (LNG) 100 mcg, followed by 7 days of 10 mcg EE in place of placebo.

Study Design: A multicenter open-label, single-treatment, Phase 3 study evaluated women aged 18 through 40 years over a treatment period of up to 1 year (four 91-day extended cycles). All subjects completed daily paper diaries to monitor compliance, bleeding and additional forms of contraception used during the course of the study.

Results: A total of 1249 subjects completed the study. The Pearl Index was 2.74 (95% confidence interval, 1.92-3.78), based on 36 pregnancies that occurred after the onset of treatment and within 14 days after the last combination tablet in women aged 18-35 years. Among compliant-use subjects 18-35 years old, the Pearl Index was 1.73 based on 22 on-treatment pregnancies. The life table pregnancy rate for subjects 18-35 years of age was 2.39%. Cycle control and adverse events reported with this regimen were similar to those reported with other low-dose OCs.

Conclusions: This study demonstrated effective prevention of pregnancy with a 20-mcg EE, 91-day extended-regimen OC. In addition, the regimen was well tolerated and incidence of adverse events were consistent with what has been reported with other low-dose OCs.