Oral vitamin K lowers INR more rapidly than subcutaneous vitamin K in asymptomatic patients who have supratherapeutic INR values while receiving warfarin.

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

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.

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]).

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