[Effect of rifampin on the metabolism of glucocorticoids in Addison's disease].

To investigate the effect of rifampicin on the metabolism of hydrocortisone, we measured serum sodium level and blood glucose concentration before lunch in a patient with Addison's disease when treated with hydrocortisone 30 mg/day alone and together with rifampicin 450 mg/day for more than two weeks. We also studied the area under the plasma cortisol curve (AUC), half-life (T 1/2) and clearance rate (CLs) of hydrocortisone after both oral ingestion and intravenous injection of 20 mg hydrocortisone. The results showed that rifampicin increased the metabolism of cortisol by shortening of its T 1/2, increasing its CLs and decreasing its AUC. It decreases the blood sodium level and glucose concentration and makes the patient liable to have hypoglycemic symptoms before lunch. We conclude that the increase of metabolism of cortisol after simultaneous taking of rifampicin may induce adrenal crisis in Addison's disease.