Menstrual cycle and oral contraceptive effects on alcohol pharmacokinetics in caucasian females.

We investigated the relationship between oral contraceptives, day of menstrual cycle and alcohol pharmacokinetics in 20 Caucasian females. Peak blood alcohol concentration was higher and clearance rates were faster on Day 1 (when hormonal levels were low) than on Day 24. No pill subjects reached a higher BAC than did pill subjects on Day 24 but not on Day 1. Clearance rates of no pill subjects were faster on Day 24 than for pill subjects. Results suggest that female sex steroids, directly or indirectly, reduce peak BAC and slow clearance rates.