INR above therapeutic range but less than 5 with no significant bleeding:
-Lower warfarin dose or omit dose
-Monitor more frequently
-Resume at lower dose when INR therapeutic
INR equal to or greater than 5 but less than 9 with no significant bleeding:
-Omit next 1 or 2 warfarin doses
-Monitor more frequently and resume at lower dose when INR in therapeutic range.
-Alternatively, omit dose and give vitamin K (5 mg or less ORALLY), particularly if at increased risk of bleeding.
-If more rapid reversal is required because the patient requires urgent surgery, vitamin K (2 to 4 mg ORALLY) can be given with the expectation that a reduction of the INR will occur in 24 hours.
-If the INR is still high, additional vitamin K (1 to 2 mg ORALLY) can be given.
INR 9 or greater with no significant bleeding:
-Hold warfarin therapy and give higher dose of vitamin K1 (5 to 10 mg ORALLY) with the expectation that the INR will be reduced substantially in 24-48 hrs.
-Monitor more frequently and use additional vitamin K if necessary.
-Resume therapy at lower dose when INR therapeutic.
Elevated INR with serious bleeding:
-Hold warfarin therapy and give vitamin K (10 mg by slow intravenous (IV) infusion), supplemented with fresh plasma, depending on the urgency of the situation
-Recombinant factor VIIa may be considered
-Vitamin K can be repeated every 12 hrs.
Life-threatening bleeding:
-Hold warfarin therapy and give vitamin K (10 mg by slow IV infusion);
-Recombinant factor VIIa may be considered
-Repeat if necessary, depending on INR.
-When vitamin K is administered to lower INRs, it should be administered at a dose that will lower the INR into a safe range quickly, without it being subtherapeutic, causing warfarin resistance, or exposing the patient to anaphylaxis risk.
-Low doses and slow infusion rates of vitamin K are recommended. If continuing warfarin therapy is indicated after high doses of vitamin K, then heparin or low molecular weight heparin can be given until the effects of vitamin K1 have been reversed and the patient becomes responsive to warfarin therapy
Intravenous Route of Administration :
-If the intravenous route of administration is considered unavoidable, the drug should not exceed an administrative rate of 1 milligram/minute. Preferably the drug should be diluted in 50-100 mL of 5% Dextrose and infused over 30 minutes.
Parenteral Route of Administration:
Severe reactions, including fatalities, have occurred during and immediately after intravenous injection of vitamin K, even when precautions have been taken to dilute the drug and to avoid rapid infusion. These reactions have also been reported following intramuscular administration. Typically these severe reactions have resembled hypersensitivity or anaphylaxis, including shock and cardiac and/or respiratory arrest. Some patients exhibited these severe reactions when they received vitamin K for the first time. Therefore the intravenous and intramuscular routes should be restricted to those situations where the subcutaneous route is not feasible and the serious risk involved is considered justified.