Warfarin . Which type of inhibitors is it
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Here is a clear, textbook-confirmed answer:
Warfarin - Type of Inhibitor
Warfarin is a Vitamin K Epoxide Reductase (VKOR) inhibitor.
Mechanism
Warfarin blocks the enzyme Vitamin K epoxide reductase complex subunit 1 (VKORC1), which is responsible for recycling (regenerating) active Vitamin K (the reduced form, Vitamin KH₂). Without this recycling, there is insufficient active Vitamin K to support the carboxylation (activation) of clotting factors.
What it inhibits (downstream effect)
By blocking Vitamin K recycling, warfarin indirectly inhibits the synthesis of Vitamin K-dependent clotting factors:
- Factor II (Prothrombin)
- Factor VII
- Factor IX
- Factor X
- Protein C and Protein S (natural anticoagulants)
From Tietz Textbook of Laboratory Medicine: "Warfarin is administered as a racemic mixture of R- and S-enantiomers, with S-warfarin being the more potent inhibitor of vitamin K epoxide reductase (VKOR) in the vitamin K cycle."
Key Classification Points
| Feature | Detail |
|---|---|
| Drug class | Coumarin anticoagulant |
| Enzyme inhibited | Vitamin K Epoxide Reductase (VKORC1) |
| Type of inhibitor | Competitive / enzyme inhibitor (specifically VKOR inhibitor) |
| Result | Reduced active Vitamin K → reduced synthesis of factors II, VII, IX, X, Protein C & S |
| Reversal | Vitamin K administration |
Comparison with Heparin (commonly tested)
- Warfarin - inhibits Vitamin K cycling (VKOR inhibitor) → reduces clotting factor synthesis
- Heparin - activates Antithrombin III (a serine protease inhibitor) → directly inactivates thrombin (IIa) and Factor Xa
So in short: Warfarin = Vitamin K Epoxide Reductase (VKOR) inhibitor.
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