Pharmacodynamic Properties of Antiplatelet Agents

Current Knowledge and Future Perspectives

Kallirroi I Kalantzi; Maria E Tsoumani; Ioannis A Goudevenos; Alexandros D Tselepis

Disclosures

Expert Rev Clin Pharmacol. 2012;5(3):319-336. 

In This Article

Abstract and Introduction

Abstract

Platelets play an important role in atherothrombotic disease. The currently available antiplatelet drugs target key steps of platelet activation including thromboxane A2 synthesis, ADP-mediated signaling, and glycoprotein IIb/IIIa-mediated platelet aggregation. The improvement of our understanding on the pharmacokinetic and pharmacodynamic characteristics of these drugs enables the tailoring of the most appropriate anti-thrombotic therapy to the individual patient and risk situation in the daily clinical practice. However, current antiplatelet therapies are associated with increased bleeding risk. Thus, further research on platelet functions may give rise to numerous new antiplatelet agents with high anti-thrombotic efficiency and low adverse hemorrhagic side effects.

Introduction

Platelet activation plays a dominant role in hemostasis, a physiologic process that prevents blood loss when the vascular endothelium is injured. However, platelets also play a critical role in the formation of pathogenic thrombi in patients with atherothrombotic disease. Indeed, the disruption of an atherosclerotic plaque promotes platelet adhesion to various subendothelial matrix proteins such as von Willebrand factor (vWF) and collagen via glycoprotein (GP) receptors on the platelet surface (GPIbα–GPIX–GPV for vWF, GPVI–FcRγ and integrin α2β1 for collagen).[1,2] Platelet adhesion results in platelet activation and secretion of various soluble agonists, including ADP, thromboxane A2 (TxA2) and thrombin. These agonists bind to distinct G-protein-coupled receptors on the platelet surface, and induce further platelet activation, secretion and platelet aggregation, which is the result of the fibrinogen binding to the activated platelet integrin receptor αIIbβ3 (GPIIb/IIIa).[3] The currently available antiplatelet agents target key steps leading to platelet activation, including TxA2 synthesis, ADP-mediated signaling and GPIIb/IIIa-mediated platelet aggregation. Furthermore, ongoing research concerns the development of specific antagonists targeting receptors of other platelet agonists such as thrombin and TxA2. The management of patients who are receiving antiplatelet drugs requires a clear understanding of the pharmacokinetics and pharmacodynamics of these drugs, as well as their possible interaction with other drugs that may influence their therapeutic efficacy. In the present review, we provide an overview of the pharmacodynamic properties of all antiplatelet drugs used in daily clinical practice and discuss future perspectives on new antiplatelet agents under development.

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