Chapter 43: Anticoagulants, Antiplatelets & Thrombolytics

Anticoagulants, Antiplatelets & Thrombolytics begins by distinguishing the pathophysiology of arterial thrombosis, driven by platelet adhesion and aggregation, versus venous thromboembolism (VTE) such as deep vein thrombosis (DVT) and pulmonary embolism (PE), which relies heavily on fibrin formation. The text extensively details the mechanism of action for parenteral anticoagulants like unfractionated heparin and low-molecular-weight heparins (LMWH) including enoxaparin, explaining how they bind to antithrombin III to inactivate thrombin and factor Xa. Critical nursing responsibilities regarding laboratory monitoring are emphasized, specifically the activated partial thromboplastin time (aPTT) for heparin and the prothrombin time (PT) and international normalized ratio (INR) for oral anticoagulants like warfarin. The summary explains the dietary impact of Vitamin K on warfarin efficacy, the risks of protein-binding interactions, and identifies protamine sulfate and phytonadione as respective antidotes for toxicity. Newer oral agents like direct thrombin inhibitors (dabigatran) and selective factor Xa inhibitors (rivaroxaban, apixaban) are contrasted regarding their lack of routine coagulation monitoring. The discussion shifts to antiplatelet drugs used for myocardial infarction and stroke prophylaxis, covering aspirin (cyclooxygenase inhibition), adenosine diphosphate (ADP) antagonists like clopidogrel, and glycoprotein IIb/IIIa receptor antagonists used during percutaneous coronary interventions. Finally, the chapter covers thrombolytics or clot busters like alteplase (tPA), describing their ability to convert plasminogen to plasmin to dissolve existing clots within a narrow therapeutic window to minimize tissue necrosis. The content concludes with comprehensive patient safety strategies, including bleeding precautions, assessing for hematuria or melena, and recognizing dangerous drug-herb interactions with supplements like ginkgo, garlic, and ginseng.