Disclosed herein is the use the S-enantiomer of anti-platelet drug oxo-clopidogrel or the derivative of formula IIA in the manufacture of a medicament for alleviating inter-individual platelet response variability and metabolic loading in humans in the treatment of thrombosis or embolism. Compositions for use in such methods comprising an (S)-oxo-clopidogrel or its derivative of the Formula IIA or a pharmaceutically acceptable salt thereof are also provided.
