How to Manage High INRs in Warfarin Patients ?

Abbreviations: FFP=fresh frozen plasma; INR=international normalized ratio; IV=intravenous; PCC=prothrombin complex concentrate; PO=oral route

a. Depending on patient condition/indication for anticoagulation, if INR over-corrected, consider heparin or lowmolecular-weight heparin until INR therapeutic.

b. All cases, INR will need to be monitored frequently until it is back in the therapeutic range. Resume warfarin at an appropriately adjusted dose once the INR is back in the therapeutic range.
c. If INR <0.5 above therapeutic range, continue current dose and check INR within one to two weeks.
d. Intravenous vitamin K works faster than oral vitamin K, but is associated with anaphylactoid reaction in  3/10,000 patients.
Recommended administration: dilute in at least 50 mL of IV fluid and infuse over at least 20 min.
No proof this reduces reaction risk.Subcutaneous injection not recommended; effect is delayed and unpredictable.

References 
1. Holbrook A, Schulman S, Witt DM, et al. Evidence-based management of anticoagulant therapy: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest 2012;141(Suppl 2):e152S-84S. 
2. Ageno W, Gallus AS, Wittkowsky A, et al. Oral anticoagulant therapy: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest 2012;141(Suppl 2):e44S-88S. 
3. Ansell J, Hirsh J, Hylek E, et al. Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians evidence-based clinical practice guidelines (8th edition). Chest 2008;133(Suppl 6):160S-98S. 
4. Wilson SE, Watson HG, Crowther MA. Low-dose oral vitamin K therapy for the management of asymptomatic patients with elevated international normalized ratios: a brief review. CMAJ 2004;170:821-4.