Contraceptive efficacy of a combined oral contraceptive containing ethinyloestradiol 20 mug/drospirenone 3mg administered in a 24/4 regimen: a pooled analysis of four open-label studies.
Author(s): Anttila L, Bachmann G, Hernadi L, Kunz M, Marr J, Klipping C
Affiliation(s): The Family Federation of Finland, Turku Clinic, Turku, Finland.
Publication date & source: 2011-04, Eur J Obstet Gynecol Reprod Biol., 155(2):180-2. Epub 2011 Feb 1.
Publication type: Clinical Trial; Multicenter Study; Randomized Controlled Trial; Research Support, Non-U.S. Gov't
OBJECTIVE: To determine the contraceptive efficacy of a low-dose combined oral contraceptive containing ethinyloestradiol (EE) 20 mug/drospirenone (drsp) 3mg administered for 24 days followed by a four-day hormone-free interval (24/4 regimen), by pooling data from four clinical trials. STUDY DESIGN: Data on the occurrence of pregnancy during treatment in four open-label trials that enrolled healthy female volunteers aged 17-36 years, who received EE 20 mug/drsp 3mg in a 24/4 regimen for 7 or 13 cycles, were pooled. RESULTS: Sixteen pregnancies occurred among 2386 women during 729,537 days (26,055 cycles) of treatment exposure, resulting in a Pearl Index (PI) of 0.80 (upper two-sided 95% confidence interval (CI) limit of 1.30). Of these pregnancies, seven were defined as method failures, resulting in an adjusted PI of 0.41 (upper two-sided 95% CI limit of 0.85), based on 616,607 days (22,022 cycles) of treatment. The Kaplan-Meier estimate for the one-year cumulative probability of contraceptive protection was 99.21%. CONCLUSIONS: The EE 20 mug/drsp 3mg combined oral contraceptive administered in a 24/4 regimen has acceptable contraceptive efficacy. Copyright (c) 2011 Elsevier Ireland Ltd. All rights reserved.