Which of the following anticoagulants has its therapeutic level monitored by INR?

Coumadin, known generically as warfarin, is the anticoagulant for which therapeutic levels are monitored by the International Normalized Ratio (INR). The INR is a standardized measure used to assess how well blood-thinning medications are working, specifically for warfarin. It provides a way to ensure that the blood's ability to clot is within the desired range—coagulation that is effective for preventing clots but not so high as to increase the risk of excessive bleeding.

The monitoring of INR is crucial when a patient is on warfarin, as various factors such as diet, other medications, or changes in health status can affect its anticoagulant effect. Thus, regular INR checks guide the dosing of warfarin to maintain a therapeutic level that minimizes the risk of clotting or bleeding complications.