Blood level of which clotting factor declines most rapidly after the initiation of warfarin therapy
Correct Answer: Factor VII
Description: WARFARIN(oral anticoagulant) Mech of action:- They act indirectly by interfering with the synthesis of vit K dependent clotting factors in liver. They apparently behave as competitive antagonists of vit K and lower the plasma levels of functional clotting factors in a dose-dependent manner. In fact, they inhibit the enzyme vit K epoxidereductase (VKOR) and interfere with regeneration of the active hydroquinone form of vit K. which acts as a cofactor for the enzyme g-glutamyl carboxylase that carries out the final step of g carboxylating glutamate residues of prothrombin and factors VII, IX and X. Factor VII has the shoest plasma t 1/2 (6 hr), its level falls first when warfarin is given, followed by factor IX (t 1/2 24 hr), factor X (t 1/2 40 hr) and prothrombin (t 1/2 60 hr). Though the synthesis of clotting factors diminishes within 2-4 hours of warfarin administration, anticoagulant effect develops gradually over the next 1-3 days as the levels of the clotting factors already present in plasma decline progressively. Ref:- kd tripathi; pg num:-620,621
Category:
Pharmacology
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now