Anticoagulants
Anticoagulants are medications that inhibit blood clot formation, thereby preventing excessive coagulation in blood vessels. They are used in conditions where clot formation can lead to serious complications, such as stroke, deep vein thrombosis (DVT), and pulmonary embolism (PE).
Classification
- 1. Heparins
- Unfractionated Heparin (UFH)
- Low Molecular Weight Heparins (LMWHs): Enoxaparin, Dalteparin
- 2. Vitamin K Antagonists (VKAs)
- Warfarin
- 3. Direct Oral Anticoagulants (DOACs)
- Direct Thrombin Inhibitor: Dabigatran
- Factor Xa Inhibitors: Rivaroxaban, Apixaban
- 4. Parenteral Direct Thrombin Inhibitors
- Argatroban, Bivalirudin
Pharmacodynamics (Mechanism of Action)
- Heparins (UFH & LMWHs)
- Enhance antithrombin III activity, leading to thrombin (Factor IIa) and Factor Xa inhibition.
- Prevents clot formation by blocking fibrin generation.
- Vitamin K Antagonists (Warfarin)
- Inhibits vitamin K-dependent clotting factors (II, VII, IX, and X).
- Delayed onset as it prevents new clotting factors from forming.
- Direct Oral Anticoagulants (DOACs)
- Dabigatran (Direct Thrombin Inhibitor): Binds to thrombin, blocking fibrin formation.
- Rivaroxaban, Apixaban (Factor Xa Inhibitors): Directly inhibit Factor Xa, interrupting the coagulation cascade.
- Parenteral Direct Thrombin Inhibitors (Argatroban, Bivalirudin)
- Directly inhibit thrombin, preventing fibrinogen conversion to fibrin.
- Used in heparin-induced thrombocytopenia (HIT).