Seeing the elevated INR the medical student wants to order vitamin K 10mg IM now to lower the INR and decrease the patient's risk of bleeding.

Do you agree or disagree with the student?

Recommendations* are:

INR elevated but < 5 with no bleeding - withhold next dose of warfarin [Coumadin®]. Consider re-starting warfarin [Coumadin®] at lower dose.

INR > 5.0 but < 9.0 with no bleeding - withhold next dose or two of warfarin [Coumadin®], consider a single low dose of oral vitamin K [Mephyton ®] (1.0 - 2.5 mg). A repeat dose can be given if the INR is still elevated at 24 hours

INR > 9 and no bleeding - a slightly higher dose of oral vitamin K [Mephyton ®] (3-5mg) should be given while withholding the warfarin [Coumadin®]. Repeat doses and duration of the warfarin-free period should be determined on repeat INRs.

If bleeding - give vitamin K [Aquamephyton®] 10mg by SLOW** IV infusion. Fresh frozen plasma may be given, esp if life threatening bleeding. Remember, although vitamin K is a specific antidote for warfarin [Coumadin®], it requires the liver to use the vitamin K and synthesize new vitamin K-dependent clotting factors (II, VII, IX, X) which may take from 12-24 hours. Fresh frozen plasma gives the patient the actual factors required to start the clotting process. If warfarin [Coumadin®] is to be continued after 'reversal' with vitamin K, heparin can be used to anti-coagulate the patient until the INR is within the desired therapeutic range again. Patients who have been 'reversed' with vitamin K are somewhat resistant to re-anticoagulation with warfarin [Coumadin®] for a period of time.

*These are recommendations since there have not been randomized clinical trials to assess the 'best' method to lower an elevated INR.

** SLOW IV infusion cannot be stressed enough. Rapid infusion or IV push of vitamin K [Aquamephyton®] can cause severe hypersensitivty reactions or anaphylaxis. This route of administration should be reserved for serious, life threatening bleeding or warfarin [Coumadin®] overdose (INR > 20.0). When this route is necessary, the rate of administration should NOT exceed 1 mg/minute and the dose should be diluted in 0.9% sodium chloride, D5%/Water, or D5%/Water in 0.9% Sodium chloride. Dilution and low administration may not prevent these above mentioned severe reactions.