Protease-Activated Receptor-1 antagonist 1 (Compound 13) is a protease-activated receptor-1 ( PAR-1 ) antagonist with the IC 50 of 3 nM by FLIPR technology. Protease-Activated Receptor-1 antagonist 1 can be used for the research of thrombotic cardiovascular, myocardial infarction, and peripheral arterial disease.