Background: A failure in incurred sample reanalysis (ISR) for N-desmethyltrimebutine (NDMT), during the analysis of a trimebutine-containing drug GIC-1001 Phase I study, led to the discovery of a never-before reported metabolite of trimebutine.
Results: A positive bias for NDMT during the ISR and post-reconstitution stability evaluations indicated the presence of an unstable metabolite of NDMT. Precursor ion scans performed on freshly extracted samples enabled the identification of this metabolite to be the NDMT glucuronide conjugate and its fragmentation pattern suggested that the glucuronide moiety was attached at the N-terminal of NDMT.
Conclusions: An acidification step was introduced in the extraction procedure to completely hydrolyze the glucuronide and measure the total NDMT in plasma, rendering this method a successful fit-for-purpose assay.