Identification of trimoprostil metabolites excreted in rat bile formed by oxidation and taurine conjugation

14C-Trimoprostil was administered iv and orally to male rats. Radioactivity was excreted mainly via the feces after both routes of drug administration. Bile duct-cannulated rats excreted an average of 76% of an iv dose in the bile within 6 hr after dosing. Four biliary metabolites were isolated by HPLC and identified by proton NMR spectroscopy and mass spectrometry. These metabolites were taurine conjugates of: trimoprostil (approximately 11% of dose), 5,6-dihydro-2,3-dinor trimoprostil (approximately 5% of dose), 3,4-dehydro trimoprostil (less than 5% of dose) and 5,6-dihydro-2,3,4,5-tetranor trimoprostil (less than 5% of dose).