The present invention relates to a method of ameliorating the drawbacks of anti-platelet drug named clopidogrel. The method of the present invention comprises administration of an (S)oxo-clopidogrel or its derivative of the Formula IIA in its free or pharmaceutically acceptable salt form for alleviating the symptoms of thrombosis or embolism by inhibiting blood platelet aggregation. Compositions for use in such methods are also provided.
