Excretion profile of glycyrrhizin metabolite in human urine

Glycyrrhizin is the main pharmacologically active component in licorice. Long term consumption of higher amounts of glycyrrhizin results in serious side effects (pseudoaldosteronism) caused by the glycyrrhizin metabolite 3β-monoglucuronyl-18β-glycyrrhetinic acid (3-MGA). The aim of this study was to determine urine excretion profile of 3-MGA. Six healthy volunteers ingested 600 mg of glycyrrhizin. In the first experimental period, glycyrrhizin was ingested in the morning and in the second experimental period, which followed after 2 weeks, glycyrrhizin was ingested in the evening. Results showed that the amount of excreted 18-MGA in urine was 1425.9–3147.8 μg, which corresponds to 0.31–0.67% of the ingested dose. Maximum elimination rates were 31.52–209.47 μg/h. There were no significant differences in the amount of excreted 3-MGA as well as in elimination rates of 3-MGA when glycyrrhizin was ingested in the morning or evening, respectively. These results provide some important clinical data on glycyrrhizin metabolism.