Apixaban, a direct oral anticoagulant (DOAC), differs from warfarin in which of the following pharmacological properties?

• A Apixaban requires regular INR monitoring and has a narrow therapeutic index like warfarin
• B Apixaban inhibits vitamin K epoxide reductase (VKOR), preventing activation of clotting factors II, VII, IX, and X
• C Apixaban directly inhibits activated factor Xa without requiring antithrombin as a cofactor, has predictable pharmacokinetics, and does not require routine coagulation monitoring ✓
• D Apixaban directly binds thrombin (factor IIa) in a reversible manner and is excreted entirely by the kidneys

Explanation

Apixaban is a direct, reversible factor Xa inhibitor — it binds activated factor Xa directly without needing antithrombin as a cofactor (unlike heparin). This results in predictable pharmacokinetics with fixed dosing and no need for routine coagulation monitoring. Warfarin works via VKOR inhibition reducing vitamin K-dependent factors. Direct thrombin (factor IIa) inhibition is the mechanism of dabigatran, not apixaban. Apixaban is primarily excreted by hepatic/biliary route (not purely renal), making it useful in mild-moderate renal impairment.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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