Identify the drug whose effectiveness is closely monitored by means of the International Normalised Ratio.

Identify the drug whose effectiveness is closely monitored by means of the International Normalised Ratio.

• A. Dabigatran
• B. Heparin
• C. Rivaroxaban
• D. Warfarin

Answer: (D)

INR is used to gauge the effect of anticoagulants that interfere with vitamin K–dependent clotting factors, most notably warfarin. Warfarin reduces the production of factors II, VII, IX, and X (and regulatory proteins C and S), which slows clotting. The International Normalised Ratio provides a standardized way to express how long the blood takes to clot (PT) so clinicians can keep anticoagulation within a safe, effective range and adjust the dose as needed. Because warfarin responses vary with diet, medications, and individual metabolism, regular INR testing is essential to maintain stroke prevention while minimizing bleeding risk. Other anticoagulants—dabigatran and rivaroxaban—have more predictable effects and do not require routine INR monitoring, and heparin is typically monitored with aPTT or anti-Xa levels rather than INR.

INR is used to gauge the effect of anticoagulants that interfere with vitamin K–dependent clotting factors, most notably warfarin. Warfarin reduces the production of factors II, VII, IX, and X (and regulatory proteins C and S), which slows clotting. The International Normalised Ratio provides a standardized way to express how long the blood takes to clot (PT) so clinicians can keep anticoagulation within a safe, effective range and adjust the dose as needed. Because warfarin responses vary with diet, medications, and individual metabolism, regular INR testing is essential to maintain stroke prevention while minimizing bleeding risk. Other anticoagulants—dabigatran and rivaroxaban—have more predictable effects and do not require routine INR monitoring, and heparin is typically monitored with aPTT or anti-Xa levels rather than INR.