Drug-induced Cushing syndrome in a patient with ulcerative colitis after betamethasone enema: evaluation of plasma drug concentration.

The authors report the induction of Cushing syndrome by daily betamethasone enema in a patient with ulcerative colitis, and they determine for the first time the pharmacokinetic profile of betamethasone after rectal dosing. The authors found high plasma concentrations of betamethasone, which could have been enough to cause Cushing syndrome. Suppression of the hypothalamus-pituitary-adrenal axis disappeared after the dose schedule was changed from every day to three times a week. These findings suggest that a considerable amount of betamethasone is absorbed after rectal dosing.