Blood Thinners Compared: Warfarin, DOACs, and Heparin
Compare warfarin, direct oral anticoagulants, and heparin products. Learn their differences in monitoring, reversal, and patient management for the PTCE exam.
Anticoagulant Classes for the PTCE
Anticoagulants (blood thinners) are high-alert medications that the PTCE tests thoroughly. Understanding the differences between drug classes, monitoring requirements, and reversal agents is essential for both the exam and patient safety.
Warfarin (Coumadin)
Mechanism: Inhibits vitamin K-dependent clotting factors (II, VII, IX, X). Monitoring: INR (International Normalized Ratio), target usually 2-3. Takes 3-5 days for full anticoagulant effect. Reversal: Vitamin K (phytonadione), fresh frozen plasma, or prothrombin complex concentrate (PCC) for emergencies. Numerous drug and food interactions (see CYP2C9 and vitamin K). Narrow therapeutic index.
Direct Oral Anticoagulants (DOACs)
- Apixaban (Eliquis) - Factor Xa inhibitor. Twice daily. Most commonly prescribed DOAC.
- Rivaroxaban (Xarelto) - Factor Xa inhibitor. Once or twice daily depending on indication. Take with food for doses above 10mg.
- Dabigatran (Pradaxa) - Direct thrombin inhibitor. Twice daily. Store in original bottle (moisture sensitive). Reversal agent: idarucizumab (Praxbind).
- Edoxaban (Savaysa) - Factor Xa inhibitor. Once daily.
Advantages over warfarin: No routine INR monitoring, fewer drug and food interactions, more predictable dosing. Reversal of Factor Xa inhibitors: andexanet alfa (Andexxa).
Heparin Products
- Unfractionated heparin (UFH) - IV or subcutaneous. Monitored by aPTT. Reversal: protamine sulfate. Risk of heparin-induced thrombocytopenia (HIT).
- Enoxaparin (Lovenox) - Low molecular weight heparin (LMWH). Subcutaneous injection. Dosed by weight. Anti-Xa levels monitored in obesity and renal impairment. Partial reversal with protamine.
Key Comparisons for the PTCE
Warfarin requires frequent monitoring but is reversible and inexpensive. DOACs offer convenience but cost more and have limited reversal options. Heparins are used acutely in hospitals. All are high-alert medications requiring careful handling.
Review anticoagulant comparisons with PTCB flashcards and practice identifying appropriate monitoring parameters.
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