Which of the following is antagonistic to vitamin-K in the synthesis of clotting factors ?

Options

A. Heparin
B. Antithrombin
C. Warfarin
D. Haemolysin

Answer

To determine which substance is antagonistic to vitamin K in the synthesis of clotting factors, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of Vitamin K**:
- Vitamin K is essential for the synthesis of certain clotting factors in the liver. These factors include prothrombin and factors VII, IX, and X, which are crucial for the blood coagulation process.

2. **Identify the Options**:
- The options provided are:
1. Heparin
2. Antithrombin
3. Warfarin
4. Hemolysis

3. **Analyze Each Option**:
- **Heparin**: This is an anticoagulant that works by activating antithrombin III, which inhibits thrombin and factor Xa. It does not directly antagonize vitamin K.
- **Antithrombin**: This is a protein that inhibits blood coagulation factors, but it does not have a direct antagonistic effect on vitamin K.
- **Warfarin**: This is a well-known anticoagulant that specifically inhibits the enzyme vitamin K epoxide reductase. This enzyme is necessary for the regeneration of active vitamin K, thereby reducing the synthesis of vitamin K-dependent clotting factors.
- **Hemolysis**: This refers to the destruction of red blood cells and is not related to the synthesis of clotting factors or vitamin K.

4. **Conclusion**:
- Among the options, warfarin is the only substance that directly antagonizes vitamin K, making it the correct answer.

### Final Answer:
The substance that is antagonistic to vitamin K in the synthesis of clotting factors is **Warfarin (Option 3)**.

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