Correction of excessive anticoagulation with low-dose oral vitamin K1.
BACKGROUND
Despite earlier acceptance of oral vitamin K1 (phytonadione) for the treatment of excessive anticoagulation, some recent guidelines do not recommend its use.


OBJECTIVE
To reevaluate the efficacy of oral vitamin K1 in correcting excessive anticoagulation.


METHODS
Case series.


METHODS
Anticoagulation clinics at two university medical centers.


METHODS
81 outpatients who had an international normalized ratio (INR) greater than 5.0 but did not have significant bleeding.


METHODS
Withholding 1 or 2 doses of warfarin, administering 2.5 mg of oral vitamin K1, measuring the INR after 24 to 48 hours, and adjusting the warfarin dose.


METHODS
INRs were obtained from a portable capillary fingerstick monitor or from an automated photooptical coagulometer.


RESULTS
In 68 of 71 patients (96%), oral vitamin K1 lowered the INR from between 5.0 and 10.0 to less than 5.0 without inducing resistance to further anticoagulation.


CONCLUSIONS
Withholding 1 or 2 doses of warfarin and administering 2.5 mg of oral vitamin K1 is a reliable, safe, and inexpensive way to rapidly correct excessive anticoagulation (INR > 5.0) in patients who do not have serious bleeding episodes and have an INR of less than 10.0.
Weibert
R T
RT
University of California, San Diego, USA.
Le
D T
DT
Kayser
S R
SR
Rapaport
S I
SI
D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014812:Vitamin K / Q000008:administration & dosage*
D000925:Anticoagulants; D014812:Vitamin K