Suppression of ovarian activity with a drospirenone-containing oral contraceptive in a 24/4 regimen

Contraception. 2008 Jul;78(1):16-25. doi: 10.1016/j.contraception.2008.02.019. Epub 2008 May 27.


Background: This study was conducted to compare ovarian activity of an oral contraceptive containing drospirenone (drsp) 3 mg plus ethinylestradiol (EE) 20 mcg administered in 24/4 regimen compared with the conventional 21/7 regimen, during intended use and following predefined dosing errors.

Study design: Women aged 18-35 years who ovulated or had a follicular diameter of >or=15 mm on or before Day 23 during a pretreatment cycle were admitted into this double-blind, randomized study. Participants underwent 3 treatment cycles with drsp 3 mg/EE 20 mcg in a 24/4 (n=52) or a 21/7 (n=52) regimen. In the third treatment cycle, the initial three pills in both groups were replaced with placebos. Ovarian activity was classified using the Hoogland scale during pretreatment and during Cycles 2 and 3.

Results: Suppression of ovarian activity was more pronounced with the 24/4 regimen--the odds ratio for a lower Hoogland score (i.e., greater ovarian suppression) with the 24/4 regimen compared with the conventional 21/7 regimen were 6.01 (95% CI: 2.29-17.94) and 3.06 (95% CI: 1.44-6.65) for Cycles 2 and 3, respectively. More women in the 24/4 regimen group had no ovarian activity 87.8% vs. 56.0% during Cycle 2 and 55.1% vs. 30.0% during Cycle 3. The 24/4 regimen was associated with a more consistent suppression (less fluctuation) of endogenous estradiol.

Conclusion: The drsp 3 mg/EE 20 mcg oral contraceptive in a 24/4 regimen was associated with greater ovarian suppression (despite intentional dosing error), which results in decreased hormonal fluctuations, and may increase contraceptive efficacy with the low-dose formulation.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Androstenes / pharmacology*
  • Confidence Intervals
  • Contraceptives, Oral, Combined*
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Drug Administration Schedule
  • Estradiol / blood*
  • Estradiol / metabolism
  • Ethinyl Estradiol / pharmacology*
  • Female
  • Humans
  • Odds Ratio
  • Ovary / drug effects*
  • Ovary / physiology
  • Treatment Outcome


  • Androstenes
  • Contraceptives, Oral, Combined
  • Ethinyl Estradiol
  • Estradiol
  • drospirenone