N-[[(5S)-2-Oxo-3-[4-(3-oxo-4-morpholinyl)phenyl]-5-oxazolidinyl]methyl]-acetamide-d4 is the isotope labelled analog of N-[[(5S)-2-Oxo-3-[4-(3-oxo-4-morpholinyl)phenyl]-5-oxazolidinyl]methyl]-acetamide. N-[[(5S)-2-Oxo-3-[4-(3-oxo-4-morpholinyl)phenyl]-5-oxazolidinyl]methyl]-acetamide is an impurity of Rivaroxaban (R538000), which is a novel antithrombotic agent. A highly potent and selective, direct FXa inhibitor.