Effect of glycyrrhizin on cortisol metabolism in humans

Urinary cortisol and cortisone excretion were measured after glycyrrhizin administration (225 mg/day, per os) for seven consecutive days in five healthy volunteers. The ratio of plasma cortisol and cortisone during hydrocortisone (0.6 mg/kg i.v.) infusion was also examined. After glycyrrhizin administration, the urinary cortisone to cortisol ratio was significantly decreased, but the ratio of plasma cortisol to cortisone was not significantly altered. Glycyrrhizin inhibited 11 beta-hydroxysteroid dehydrogenase in the kidney and so inhibited the conversion of cortisol to cortisone. The increased cortisol in the kidney could be the cause of the apparent mineralocorticoid excess syndrome induced by glycyrrhizin.