Platelets and Purinergic receptors:
The major class of receptors present over platelets is the purinergic receptors. They are of three subtypes P2Y1, P2Y12 and P2X1. The first two are G-Protein coupled receptors and the last one is Adenosine gated ion channel receptor. ADP is the physiological activator of platelets that mediate its effects via these receptors. P2Y1 is Gq coupled that act through phospholipase c system and P2Y12 is Gαi coupled that act by adenyl cyclase system [4]. P2X1 acts via influx of calcium functionally they produce only conformational changes in the platelets along with synergistic action with other 2 receptors [5]. There are several drugs that target these receptors. P2Y12 is the major receptor involved in activation of GPIIb/IIIa receptors This is blocked by a group of drugs called non-thienopyridines namely elinogrel, ticagrelor and cangrelor [6]. Other than these there are various drugs that target various other pathways of platelet aggregation, one among them is the class called ADP inhibitors. They act by inhibiting ADP which is the physiological activator of platelets. The drugs include clopidogrel and prasugrel [6]. So, the purinergic receptors not only play an important role in physiological homeostasis of platelets but also serve as important drug targets for treating various life threatening and common diseases. These antiplatelet drugs are one of the most common drugs used in clinical practice. These antiplatelet drugs are used in prophylaxis of various hypercoagulable states including Myocardial infarction and atherosclerosis. Clopidogrel is used along with atorvastatin and aspirin as loading dose in Myocardial infarction. This strategy is known to reduce the development of reinfarction substantially and provides benefits in patients with MI undoubtedly [7].