The bioavailability of ethinyloestradiol and levonorgestrel in patients with an ileostomy

The bioavailability of ethinyloestradiol and levonorgestrel has been studied in 5 young women with an ileostomy following surgery for ulcerative colitis and compared to that in 5 control subjects. Single i.v. and oral doses of both drugs were administered and the bioavailability calculated from the ratio of the two areas under the plasma concentration versus time curve for the two drugs. The mean bioavailability of ethinyloestradiol in the patients with an ileostomy was 55.4 +/- 10.9% (+/- S.D.) compared to a control value of 45.0 +/- 6.1% (p greater than or equal to 0.1). The mean bioavailability of levonorgestrel in the ileostomy patients was 85.2 +/- 13.1% compared to 104.6 +/- 22.3% in the controls (p greater than or equal to 0.1). Women who have an ileostomy following lower bowel surgery can rely on their oral contraceptive preparations being absorbed in the normal way.