Transdermal delivery of ethinyl estradiol (EE) may be increased in conditions when core body temperature is elevated, such as during exercise. Our aims were to determine the effect of acute aerobic exercise on EE from the transdermal contraceptive patch and examine the correlation between changes in core body temperature and EE.
This was a prospective open-label, crossover (exercise and resting/control) study.
Patients and methods
Eight premenopausal volunteers were provided standard 4-week regimen of the transdermal contraceptive patch. During the second or third week of transdermal contraceptive patch, participants rode a cycle ergometer at 70–75% VO2peak for 30 min twice, counterbalanced with a control (seated) condition during the opposing week. Immediately following all sessions, serial blood samples were taken for 3 h. A repeated measures analysis of variance was used for comparison of EE parameters after adjusting for changes in plasma volume; relationships were examined using Pearson’s correlations.
Peak EE concentration (158.9±74.3 pg/ml) was greater than the initial concentration (115.3±59.3 pg/ml) (P=0.032) only after the first exercise session. Differences were not observed for peak or steady state EE concentrations, as well as area under the curve, between exercise and resting conditions. No relationships were observed between changes in core body temperature and EE.
These outcomes demonstrate that 30 min of moderate-intensity exercise in a thermoneutral environment did not exacerbate EE parameters in premenopausal women.