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

Ann Intern Med. 2002 Aug 20;137(4):251-4. doi: 10.7326/0003-4819-137-4-200208200-00009.


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.

Design: Randomized, controlled trial.

Setting: Two teaching hospitals.

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

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

Measurements: 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]).

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

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Aged
  • Anticoagulants / adverse effects*
  • Blood Coagulation Disorders / chemically induced*
  • Blood Coagulation Disorders / drug therapy*
  • Female
  • Humans
  • Injections, Subcutaneous
  • International Normalized Ratio*
  • Male
  • Middle Aged
  • Risk Factors
  • Vitamin K / administration & dosage*
  • Warfarin / adverse effects*


  • Anticoagulants
  • Vitamin K
  • Warfarin