Conclusions
Similar to preclinical experiments, total asundexian-derived radioactivity is cleared quantitatively predominantly via feces. Excretion occurs mainly via amide hydrolysis and as the unchanged drug.
Methods
The mass balance, biotransformation, and excretion pathways of asundexian were investigated in six healthy volunteers (single oral dose of 25 mg [14C]asundexian) and in BDC rats (intravenous [14C]asundexian 1 mg/kg).
Results
Overall recovery of radioactivity was 101% for humans (samples collected up to 14 days after dosing), and 97.9% for BDC rats (samples collected in the 24 h after dosing). Radioactivity was mainly excreted into feces in humans (80.3%) and into bile/feces in BDC rats (> 94%). The predominant clearance pathways in humans were amide hydrolysis to metabolite M1 (47%) and non-labeled M9 with subsequent N-acetylation to M10; oxidative biotransformation was a minor pathway (13%). In rats, hydrolysis of the terminal amide to M2 was the predominant pathway. In human plasma, asundexian accounted for 61.0% of total drug-related area under the plasma concentration-time curve (AUC); M10 was the major metabolite (16.4% of the total drug-related AUC). Excretion of unmetabolized drug was a significant clearance pathway in both species (human, ~ 37%; BDC rat, ~ 24%). The near-complete bioavailability of asundexian suggests negligible limitations on absorption and first-pass metabolism. Comparison with radiochromatograms from incubations with human or rat hepatocytes indicated consistency across species and a good overall in vitro/in vivo correlation. Conclusions: Similar to preclinical experiments, total asundexian-derived radioactivity is cleared quantitatively predominantly via feces. Excretion occurs mainly via amide hydrolysis and as the unchanged drug.