A competitive antagonist at P2Y1 receptors (KB = 100 nM). Selective over P2X1 (IC50 = 1.15 μM), P2X3 (IC50 = 12.9 μM), P2X2, P2X4, P2Y2, P2Y4 and P2Y6 receptors. Inhibits the upregulation of NTPDase1 by ATPγS.