Which statement about dabigatran's mechanism is true?

Which statement about dabigatran's mechanism is true?

• A. Directly binds to thrombin (Factor IIa)
• B. Inhibits Factor Xa
• C. Inhibits vitamin K epoxide reductase
• D. Inhibits platelet aggregation

Answer: (A)

Dabigatran works by directly inhibiting thrombin, the enzyme known as Factor IIa. It binds to thrombin’s active site, preventing it from converting fibrinogen to fibrin and from propagating the coagulation cascade. This direct blockade of thrombin is what reduces clot formation and thrombin-mediated amplification. This mechanism is different from drugs that inhibit Factor Xa, which stop the cascade one step earlier by blocking Factor Xa. It’s also not a vitamin K antagonist like warfarin, which works by reducing the synthesis of multiple vitamin K–dependent clotting factors. And it’s not primarily an antiplatelet agent, whose main action is on platelets rather than the coagulation factors. In emergencies, dabigatran can be reversed with idarucizumab, a specific antibody fragment that neutralizes the drug.

Dabigatran works by directly inhibiting thrombin, the enzyme known as Factor IIa. It binds to thrombin’s active site, preventing it from converting fibrinogen to fibrin and from propagating the coagulation cascade. This direct blockade of thrombin is what reduces clot formation and thrombin-mediated amplification.

This mechanism is different from drugs that inhibit Factor Xa, which stop the cascade one step earlier by blocking Factor Xa. It’s also not a vitamin K antagonist like warfarin, which works by reducing the synthesis of multiple vitamin K–dependent clotting factors. And it’s not primarily an antiplatelet agent, whose main action is on platelets rather than the coagulation factors. In emergencies, dabigatran can be reversed with idarucizumab, a specific antibody fragment that neutralizes the drug.