Which medication is a vitamin K antagonist that may increase ocular bleeding risk?

Which medication is a vitamin K antagonist that may increase ocular bleeding risk?

• A. Plavix
• B. NSAIDs
• C. Aspirin
• D. Warfarin

Answer: (D)

Warfarin is a vitamin K antagonist that reduces the production of vitamin K–dependent clotting factors II, VII, IX, and X (as well as proteins C and S) by inhibiting vitamin K–reductase. This decreases the blood’s clotting ability and increases bleeding risk, including in ocular tissues. The other medications work through different mechanisms: antiplatelet agents like clopidogrel (Plavix) and aspirin, as well as NSAIDs, impair platelet function or COX activity but do not inhibit vitamin K–dependent factor synthesis. Therefore, the medication that may increase ocular bleeding risk specifically through vitamin K antagonism is warfarin.

Warfarin is a vitamin K antagonist that reduces the production of vitamin K–dependent clotting factors II, VII, IX, and X (as well as proteins C and S) by inhibiting vitamin K–reductase. This decreases the blood’s clotting ability and increases bleeding risk, including in ocular tissues. The other medications work through different mechanisms: antiplatelet agents like clopidogrel (Plavix) and aspirin, as well as NSAIDs, impair platelet function or COX activity but do not inhibit vitamin K–dependent factor synthesis. Therefore, the medication that may increase ocular bleeding risk specifically through vitamin K antagonism is warfarin.