Reversal of
Vitamin-K Antagonists
Guidelines for Management for Nontherapeutic INR for
patient on Warfarin Therapy
Case AF อายุ 73 ปี
INR 7.30 PT 68.20 -> No bleeding
Off warfarin 2 วัน
Vitamin K 2 mg PO
Vitamin K1 (Phytomenadione)
2 mg / 0.2 ml
10 mg / 1 ml
 Oral route
 Intravenous route
 Subcutaneous route
 Intramuscular route
Reversal of Vitamin-K Antagonists
Pharmacokinetic of Vitamin K
IV


Do not use intravenously unless unavoidable.
Elevated INR with serious bleeding
Hold warfarin therapy and give vitamin K1 (10 mg by
slow intravenous (IV) infusion), supplemented with fresh
plasma or prothrombin complex concentrate, depending
on the urgency of the situation; recombinant factor VIIa
may be considered as alternative to prothrombin complex
concentrate; vitamin K1 can be repeated every 12 hrs.
 Life-threatening bleeding
Hold warfarin therapy and give prothrombin complex
concentrate supplemented with vitamin K1 (10 mg by
slow IV infusion); recombinant factor VIIa may be
considered as alternative to prothrombin complex
concentrate; repeat if necessary, depending on INR.
IV
INTRAVENOUS RATE OF ADMINISTRATION
If the intravenous route of administration is
considered unavoidable, the drug should not
exceed an administrative rate of 1
milligram/minute.
When vitamin K1 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 K1, 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.
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