Oral vitamin K lowers the international normalized ratio more rapidly than subcutaneous vitamin K in the treatment of warfarin-associated coagulopathy. A randomized, controlled trial.
BACKGROUND
Excessive anticoagulation due to warfarin use is associated with hemorrhage. Subcutaneously administered vitamin K has not been evaluated for the treatment of warfarin-associated coagulopathy, yet it is widely used.


OBJECTIVE
To show that oral vitamin K is more effective than subcutaneous vitamin K in the treatment of warfarin-associated coagulopathy.


METHODS
Randomized, controlled trial.


METHODS
Two teaching hospitals.


METHODS
Patients with an international normalized ratio (INR) between 4.5 and 10.0.


METHODS
Warfarin therapy was withheld, and 1 mg of vitamin K was given orally or subcutaneously.


METHODS
The primary outcome measure was the INR on the day after administration of vitamin K. Secondary outcome measures were hemorrhage and thrombosis during a 1-month follow-up period.


RESULTS
15 of 26 patients receiving oral vitamin K and 6 of 25 patients receiving subcutaneous vitamin K had therapeutic INRs on the day after study drug administration (P = 0.015; odds ratio, 4.32 [95% CI, 1.13 to 17.44]).


CONCLUSIONS
Oral vitamin K lowers INR more rapidly than subcutaneous vitamin K in asymptomatic patients who have supratherapeutic INR values while receiving warfarin.
Crowther
Mark A
MA
St. Joseph's Hospital, 50 Charlton Avenue East, Hamilton, Ontario L8N 4A6, Canada. crowthrm@mcmaster.ca
Douketis
James D
JD
Schnurr
Terri
T
Steidl
Luigi
L
Mera
Valentina
V
Ultori
Carolina
C
Venco
Achille
A
Ageno
Walter
W
D000284:Administration, Oral; D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects*; D001778:Blood Coagulation Disorders / Q000139:chemically induced* / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D014812:Vitamin K / Q000008:administration & dosage*; D014859:Warfarin / Q000009:adverse effects*
D000925:Anticoagulants; D014812:Vitamin K; D014859:Warfarin