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Archive for November 13th, 2009

Pharm Friday – Antiplatelet Agents Overview

Posted by medliorator on November 13, 2009

Another home run from our friends at Pharmamotion:



  • ADP Antagonists: thienopyridines act by inhibiting the ADP-dependent pathway of platelet activation. These drugs have no direct effect on prostaglandin metabolism.
    • Ticlopidine …is approved for secondary prevention of thrombotic strokes in patients intolerant of aspirin and for prevention of stent thrombosis in combination with aspirin.  adverse effects [include] neutropenia, thrombocytopenia and thrombotic thrombocytopenic purpura.
    • Clopidogrel is approved for prevention of atherosclerotic events following recent myocardial infarction, stroke or established peripheral arterial disease. It is also approved for use in acute coronary syndromes that are treated with either PCI  or coronary artery bypass grafting. It has a better safety profile than ticlopidine.
  • Aspirin: aspirin inhibits platelet cyclooxygenase, a key enzyme in thromboxane A2 (TXA2) generation. Thromboxane A2 triggers reactions that lead to platelet activation and aggregation, aspirin acts as a potent antiplatelet agent by inhibiting generation of this mediator. These effects last for the life of the anucleate platelet, approximately 7 to 10 days… indicated as prophylaxis against transient ischemic attacks, myocardial infarction and thromboembolic disorders. It is also used for the treatment of acute coronary syndromes
  • Phosphodiesterase inhibitors: Dipyridamole acts as vasodilator and antiplatelet agent. It inhibits adenosine uptake and cyclic GMP phosphodiesterase activity, this decreases platelet aggregability  …it is currently used in combination with aspirin or warfarin in the prophylaxis of thromboembolic disorders.  It is also used in stress testing for myocardial perfusion imaging.
  • GPIIb/IIIa inhibitors: used parenterally in patients with acute coronary syndromes…  the integrin GPIIb/IIIa antagonists prevent cross-linking of platelets… current indications include unstable angina that does not respond to conventional therapy in patients that undergo percutaneous coronary intervention.

Antiplatelet agents: mechanisms of action and general overview [Pharmamotion]

Posted in Cardiology, Pharmacology | 2 Comments »