Vorapaxar molecule, space-filled model. Vorapaxar (C29.H33.F.N2.O4) is a thrombin receptor (protease-activated receptor, PAR-1) antagonist based on the natural product himbacine. Vorapaxar is used for those with a history of myocardial infarction (heart attack) or those with peripheral arterial disease. It is an anti-platelet drug that does not interfere with thrombin activity. The atoms are colour-coded: carbon (grey), hydrogen (white), nitrogen (blue), oxygen (red), fluorine (green).