Chapter 28: Coagulation Modifier Drugs – Anticoagulants & Antiplatelets

Coagulation modifiers are categorized into four primary classes: Anticoagulants, which inhibit clotting factor action to prevent new clot formation or expansion, include unfractionated heparin (which utilizes antithrombin III and is monitored by aPTT) and warfarin (an oral vitamin K antagonist monitored by INR/PT). Newer anticoagulants like low-molecular-weight heparins (LMWHs) and novel oral anticoagulants (NOACs), such as direct thrombin inhibitors (e.g., dabigatran) and selective factor Xa inhibitors (e.g., fondaparinux), often offer therapeutic effects without the need for intensive lab monitoring. Antiplatelet drugs, including acetylsalicylic acid (Aspirin) and clopidogrel, target platelet adhesion and aggregation to prevent platelet plug formation. For emergency treatment, thrombolytic drugs (e.g., alteplase) actively dissolve existing clots by converting plasminogen to plasmin. Finally, antifibrinolytic drugs (e.g., tranexamic acid, desmopressin) promote coagulation by preventing the lysis of fibrin. Throughout the chapter, emphasis is placed on the high-alert nature of these medications, the importance of monitoring for bleeding (the primary adverse effect), required laboratory tests (aPTT, PT, INR), specific contraindications (such as heparin-induced thrombocytopenia or LMWH use with an epidural catheter), and the use of specific antidotes, such as protamine sulfate for heparin overdose and vitamin K for warfarin overdose.