How to decrease International Normalized Ratio (INR)?

From the Guidelines

To decrease INR, the most effective approach is to administer vitamin K1, typically 1-2.5 mg orally, which can rapidly lower the INR within 24 hours, as evidenced by a study published in the Journal of the American College of Cardiology 1.

Approaches to Decrease INR

• Temporarily stopping or reducing warfarin (Coumadin) dose as directed by the doctor
• Administering vitamin K1 (phytonadione) orally or intravenously, depending on the severity of the situation
• Using fresh frozen plasma, prothrombin complex concentrate, or recombinant factor VIIa in emergency cases with active bleeding

Considerations for Vitamin K1 Administration

• Oral administration is predictably effective and has the advantages of convenience and safety over parenteral routes
• The dose of vitamin K1 should be chosen to quickly lower the INR into a safe but not subtherapeutic range without causing resistance once warfarin is reinstated
• High doses of vitamin K1 (e.g., 10 mg) may lower the INR more than necessary and lead to warfarin resistance for up to a week

Importance of Medical Supervision

• Patients should avoid self-medicating with vitamin K supplements without medical supervision
• Regular INR monitoring is essential during any intervention to prevent overcorrection, which could increase clotting risk

Additional Considerations

• Dietary modifications can help moderately lower INR by increasing vitamin K intake through foods like leafy greens, broccoli, Brussels sprouts, and cabbage
• The choice of approach to decrease INR should be based on clinical judgment, taking into account the patient's individual risk factors and medical history, as well as the latest guidelines from reputable medical organizations, such as the American Heart Association 1.

From the FDA Drug Label

The following factors, alone or in combination, may be responsible for DECREASED PT/INR response: ENDOGENOUS FACTORS: edema hypothyroidism hereditary coumarin resistance nephrotic syndrome hyperlipemia EXOGENOUS FACTORS: Potential drug interactions with warfarin sodium tablets are listed below by drug class and by specific drugs Classes of Drugs also: diet high in vitamin K unreliable PT/INR determinations * Increased and decreased PT/INR responses have been reported † Vitamins† Specific Drugs Reported: alcohol* warfarin sodium underdosage phenytoin* aminoglutethimide cyclophosphamide* pravastatin* amobarbital dicloxacillin prednisone*

To decrease International Normalized Ratio (INR), consider the following key factors:

• Diet: Increase intake of foods high in vitamin K, such as leafy green vegetables.
• Medications: Certain medications, such as phenytoin, aminoglutethimide, and cyclophosphamide, may decrease INR.
• Underdosage: Ensure that the patient is not taking too little warfarin.
• Other factors: Consider other factors that may affect INR, such as edema, hypothyroidism, hereditary coumarin resistance, nephrotic syndrome, and hyperlipemia. It is essential to consult the patient's healthcare provider before making any changes to their medication or diet, as the management of INR requires careful monitoring and individualized care 2.

From the Research

Methods to Decrease International Normalized Ratio (INR)

• Withhold warfarin and recheck INR in 1 to 2 days for patients with an elevated INR and mild or no bleeding 3
• Add oral vitamin K supplementation if INR >5 3
• For major bleeding and elevated INR, hospital admission, vitamin K, fresh frozen plasma, and frequent monitoring are needed 3
• In emergent situations, hospitalization, clotting factor replacement, and vitamin K administered by slow intravenous infusion are required 3
• Adjusting a steady-state warfarin dose depends on the measured INR values and clinical factors, with most changes altering the total weekly dose by 5% to 20% 4
• Patients who have an elevated INR will need more frequent testing and may also require vitamin K1, such as 2.5 mg phytonadione by mouth for a nonbleeding patient with an INR of 9 4
• For patients initiating prednisone therapy, preemptive warfarin dose reduction may result in a non-significant reduction in supratherapeutic INR but increases the likelihood of subtherapeutic INR compared to INR monitoring with reactive warfarin dose adjustment 5
• Prothrombin complex concentrates (PCC) can be used for warfarin reversal, with PCC use associated with a significant reduction in all-cause mortality compared to fresh frozen plasma (FFP) 6
• PCC use is more likely to achieve normalization of INR and results in a shorter time to INR correction compared to FFP 6
• Administration of PCC with or without vitamin K seems to be more effective in rapidly correcting increased INR levels than vitamin K treatment without PCC 7