Ursodeoxycholic acid-d4 (UDCA-d4) is intended for use as an internal standard for the quantification of UDCA (Item No. 15121) by GC- or LC-MS. UDCA is a secondary bile acid formed via epimerization of chenodeoxycholic acid (CDCA; ). UDCA is also a metabolite of lithocholic acid (LCA; ) in human liver microsomes. It inhibits taurocholic acid uptake in HeLa cells expressing recombinant sodium/taurocholate cotransporting polypeptide (NTCP) with an IC50 value of 3.6 μM. UDCA (50 μM) inhibits apoptosis induced by deoxycholic acid (DCA; Item Nos. 20756 | 18231) or ethanol in primary rat hepatocytes. Dietary administration of UDCA blocks DCA-induced increases in the number of TUNEL-positive hepatocytes in rats. Formulations containing UDCA have been used in the treatment of primary biliary cirrhosis.
