Metabolic profiling of a novel antithrombotic compound, S002-333 and enantiomers: metabolic stability, species comparison and in vitro-in vivo extrapolation.

ABSTRACT

OBJECTIVE: The aim of this research work was to characterize the metabolism of S002-333, (2-(4'-methoxy-benzenesulfonyl)-2,3,4,9-tetrahydro-1H-pyrido (3,4-b) indole-3-carboxylic acid amide) and its enantiomers, S004-1032 (R-form) and S007-1558 (S-form) in pooled human liver microsomes (PHLM) and pooled liver microsomes (LM) of rat (RLM), rabbit (RABLM), dog (DLM) and monkey (MLM). Another objective of this study was to identify suitable surrogate species to humans for further development of lead candidates. METHOD: In vitro metabolic stability and metabolite identification of S002-333 and enantiomers were carried out in PHLM and LM of various species. The prediction of surrogate species and in vitro in vivo extrapolation were performed based upon the calculated in vitro intrinsic clearance (CLint ). RESULTS/CONCLUSION: The in vitro CLint values for S002-333, S004-1032 and S007-1558 were 0.027 ± 0.005, 0.025 ± 0.004 and 0.036 ± 0.005 ml/min/mg, respectively, in PHLM, indicating that S007-1558 was the most metabolically unstable of the three. The LM of other species showed similar results. A common surrogate species to humans for S002-333 and enantiomers was predicted as rabbit where the extrapolated hepatic clearance (CLH ) did not show a significant difference to the in vivo CLH values. However, none of the species closely mimic humans with respect to the proportion of major metabolites (M-1-M-4) formed in vitro. Likewise, the CLH values were also predicted in humans for S002-333 and enantiomers using various mathematical models. During analysis, there was no chiral inversion evident among the individual isomers throughout in vitro and in vivo experiments. In conclusion, the in vitro results indicate a prominent role of phase I metabolism in the degradation of S002-333 and enantiomers and predict rabbit as an alternative species to conduct further safety and efficacy studies. Copyright © 2016 John Wiley & Sons, Ltd.