Lack of effect of alcohol on ethinylestradiol in premenopausal women

An acute elevation in estradiol during alcohol intake has been reported in postmenopausal women on estrogen replacement therapy. The objective of the present study was to investigate the acute and long-term effect of alcohol on ethinylestradiol, the estrogen component found in most oral contraceptives. Nine healthy premenopausal women with regular use of an oral contraceptive containing 30 μg ethinylestradiol and 75 μg gestodene were challenged with alcohol (0.4 g/kg p.o., approximately 2–3 standard drinks) 2 h after intake of the oral contraceptive pill at menstrual cycle day 14. Blood samples were taken at 0, 2, 3, 4, 5, and 6 h from intake of alcohol. The challenge was repeated after a 7-day period of controlled alcohol intake (0.8 g/kg/day) at cycle day 21. The same experiments were carried out during placebo conditions. At day 21 an increase in the alcohol elimination rate was observed compared with day 14. No significant acute or long-term effect of alcohol on ethinylestradiol was found. The lack of an acute effect comparable to that reported for estradiol may be due to the protection of the ethinyl group at the 17-position of ethinylestradiol.