Influence of menstrual cycle on antipyrine pharmacokinetics in healthy Indian female volunteers.

The effect of the menstrual cycle on antipyrine pharmacokinetics was studied in 11 normal, healthy Indian female volunteers. Antipyrine half-life, apparent volume of distribution, clearance and AUC were calculated by standard methods. Results indicated that in females, antipyrine half-life was significantly longer on day 5 as compared with that on days 15 and 21 of the menstrual cycle. It appears that hormonal changes during the menstrual cycle affect the pharmacokinetics of drugs in normal healthy females.