Answer
The INR shows how long blood takes to clot and helps the anticoagulation service keep phenindione's effect within the intended range.
Sources for this answer
- Dindevan 25mg Tablets / Phenindione 25mg Tablets — Current selected SmPCemc · Summary of Product Characteristics
- NHSNHS · NHS medicine guidance
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.