Clinical experience with oral versus intravenous vitamin K for warfarin reversal.
BACKGROUND
Reversal of warfarin with plasma accounts for a large amount of fresh-frozen plasma transfused in the United States. The use of vitamin K is an alternate strategy.


METHODS
Records of vitamin K prescriptions for warfarin reversal were examined and recipients identified where data were available on dosage, route of administration (oral [PO] and intravenous [IV]) and the availability of both pre- and postadministration international normalized ratio(s) (INRs).


RESULTS
A total of 135 administration events were evaluated: 81 PO and 54 IV. The median (range) preadministration INRs were 5.8 (1.9-16.5) versus 5.0 (1.4-16.5; p=0.61) and the median (range) for the postadministration INRs were 2.4 (1.0-10.4) and 2.1 (1.2-8.2; p<0.01) for the PO and IV routes, respectively. The median (range) doses were 2.5(1-10) and 2.0(1-10) mg for PO and IV, respectively (p<0.01). A total of 44% of the IV vitamin K group achieved an INR of 2 or less within 12 hours versus 14% for the PO route (p<0.01). In multilinear regression the preadministration INR (r=0.14, p<0.01) and time after administration (r=-0.05, p<0.01) were independent variables influencing the postadministration INR but the dose administered (r=0.09, p=0.07) was not.


CONCLUSIONS
Vitamin K needs to be given IV if urgent partial correction (<12 hr) of warfarin is required. No influence of dose administered in the range 1 to 10 mg on the postadministration INR was observed.
From the Blood Bank and Department of Medicine, Roger Williams Hospital, Providence, Rhode Island.
Robert
R
Meehan
Maria
M
Tavares
Joseph
J
Sweeney
D061605:Administration, Intravenous; D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects / Q000037:antagonists & inhibitors; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010818:Practice Patterns, Physicians' / Q000639:trends; D012189:Retrospective Studies; D014812:Vitamin K / Q000008:administration & dosage* / Q000009:adverse effects; D014859:Warfarin / Q000008:administration & dosage / Q000009:adverse effects* / Q000037:antagonists & inhibitors*
D000925:Anticoagulants; D014812:Vitamin K; D014859:Warfarin