The effect of rifampicin oh the pharmacokinetics of ethynylestradiol in women

Abstract A single dose of Minovlar R (50 μg ethynylestradiol (EE) and 1 mg norethindrone acetate) was given to seven women during treatment with rifampicin (450–600 mg/day) and again one month after stopping rifampicin. Blood samples were taken at intervals over a 24-hour period . The area under the plasma EE versus time curve increased significantly on stopping rifampicin from 1014 ± 317 pg/ml × h (mean ± SE) to 1747 ± 218 pg/ml × h (p