Glycyrrhizin (GCR)

Glycyrrhizin is the chief sweet-tasting constituent of Glycyrrhiza glabra (liquorice) root. It has also been given intravenously in Japan as a treatment for hepatitis C and as an emusifier and gel-forming agent in foodstuff and cosmetics. After oral ingestion, glycyrrhizin is first hydrolysed to 18β-glycyrrhetinic acid by intestinal bacteria. After complete absorption from the gut, β-glycyrrhetinic acid is metabolised to 3β-monoglucuronyl-18β-glycyrrhetinic acid in the liver. This metabolite then circulates in the bloodstream. Consequently its oral bioavailability is poor. The main part is eliminated by bile and only a minor part (0.31–0.67%) by urine. After oral ingestion of 600 mg of glycyrrhizin the metabolite appeared in urine after 1.5 to 14 hours. Maximal concentrations (0.49 to 2.69 mg/l) were achieved after 1.5 to 39 hours and metabolite can be detected in the urine after 2 to 4 days.