PT  - JOURNAL ARTICLE
AU  - Toshiaki Makino
AU  - Nobuhiro Ohtake
AU  - Akito Watanabe
AU  - Naoko Tsuchiya
AU  - Sachiko Imamura
AU  - Seiichi Iizuka
AU  - Makoto Inoue
AU  - Hajime Mizukami
TI  - Down-Regulation of a Hepatic Transporter Multidrug Resistance-Associated Protein 2 Is Involved in Alteration of Pharmacokinetics of Glycyrrhizin and Its Metabolites in a Rat Model of Chronic Liver Injury
AID  - 10.1124/dmd.108.021089
DP  - 2008 Jul 01
TA  - Drug Metabolism and Disposition
PG  - 1438--1443
VI  - 36
IP  - 7
4099  - http://dmd.aspetjournals.org/content/36/7/1438.short
4100  - http://dmd.aspetjournals.org/content/36/7/1438.full
SO  - Drug Metab Dispos2008 Jul 01; 36
AB  - Glycyrrhizin (GL) has been used to treat chronic hepatitis in Japan and Europe. It is thought to induce pseudoaldosteronism via inhibition of type 2 11β-hydroxysteroid dehydrogenase (11β-HSD2) by glycyrrhetinic acid (GA), a major metabolite of GL. A previous clinical study suggested that 3-monoglucuronyl-glycyrrhetinic acid (3MGA), another metabolite of GL, might play a more important role in the pathogenesis of pseudoaldosteronism. The present study evaluates the pharmacokinetics of GL and its metabolites in rats with chronic liver injury induced by a choline-deficient l-amino acid-defined (CDAA) diet to clarify the relationship between 3MGA and pseudoaldosteronism. In rats fed a CDAA diet, plasma concentrations and urinary eliminations of GL and 3MGA were markedly higher than in the rats fed the control diet; the plasma concentration of GA was unaffected when GL was orally administered. Immunohistochemical analysis revealed the suppression of levels of multidrug resistance-associated protein (Mrp) 2 and its localization in the hepatic tissue of rats fed a CDAA diet. When 3MGA was i.v. injected in rats fed a CDAA diet or injected in Mrp2-dysfunctional Eisai hyperbilirubinemic rats, plasma concentrations of 3MGA were higher, and biliary excretion of 3MGA was lower than in each control group. The results suggested that 3MGA would be excreted to bile via hepatic Mrp2 and that its dysfunction would reduce 3MGA clearance. 3MGA accumulated by liver fibrosis resulted in the increased excretion through renal tubule and might be strongly related to the pathogenesis of pseudoaldosteronism because 11β-HSD2 is expressed in renal tubular epithelial cells. The American Society for Pharmacology and Experimental Therapeutics