A comparison of the efficacy and rate of response to oral and intravenous Vitamin K in reversal of over-anticoagulation with warfarin

The role of oral Vitamin K administration in the reversal of anticoagulatio n is not yet clear because of a paucity of data on the early effects of tre atment, apparent differences in efficacy between preparations and a lack of data comparing oral with intravenous administration. We have compared the effects on the International Normalized Ratio (INR) and activities of the V itamin K-dependent clotting factors II, VII, IX and X at 4 h and 24 h after administration of three oral Vitamin K preparations and of intravenous Vit amin K in 64 anticoagulated patients who required non-urgent partial correc tion of anticoagulation, Our data confirm that correction of anticoagulatio n is more rapid after intravenous administration of Vitamin K than after or al administration of similar or larger doses. At 24 h, satisfactory correct ion of INR can be achieved using low-dose Vitamin K given by either the int ravenous or oral route. Our data, and that from previous studies, suggest t hat there may be differences in efficacy between orally administered produc ts. Administration of Vitamin K by either route was accompanied by changes in the activities of the Vitamin K-dependent clotting factors that reflecte d their respective biological half-lives. In the 24 h after treatment, the relationship between the INR and the individual Vitamin K-dependent clottin g factors was similar to that described previously in stable anticoagulated patients. We conclude that the reversal of anticoagulation with warfarin i s achieved more rapidly by intravenous administration of Vitamin K. Satisfa ctory, but slower, reversal of anticoagulation can be effected using oral V itamin K, but there may be differences in efficacy between the products tes ted in our study.