Isolation of an unknown metabolite of the non-steroidal anti-inflammatory drug etodolac and its identification as 5-hydroxy etodolac.

ABSTRACT

The non-steroidal anti-inflammatory drug etodolac is extensively metabolized in the liver. Renal elimination of etodolac mainly as glucuronide and its other phase I and phase II metabolites is the primary route of excretion. High-performance liquid chromatography assays of human urine after application of etodolac indicated the existence of a further monohydroxylated metabolite (metabolite X) that was identified as 5-hydroxy etodolac. For the identification, electrospray ionization mass spectrometry (ESI-MS) as well as 1H-nuclear magnetic resonance (1H-NMR) and 13C-NMR spectroscopy have been used.