An observational study suggests that vitamin K may be a viable alternative to plasma for warfarin reversal. Published in the journal Transfusion, the study evaluated 135 patients who had been prescribed oral or intravenous vitamin K for warfarin reversal.
Warfarin is the most commonly prescribed anticoagulant in the United States, but often requires frequent monitoring to balance anticoagulation with the risk of bleeding. Coagulation is monitored using the international normalized ratio, or INR. A high INR indicates a high risk of bleeding. Patients with high INRs may require omission of a warfarin dose or more aggressive measures, including vitamin K therapy or plasma infusion.
Dr. Joseph Sweeney, who led the study noted:
“This represents the largest reported observational study with a wide range in pretreatment INRs for both oral and IV vitamin K.”
In this study, researchers found substantial variation in the doses of vitamin K prescribed, but dosage did not affect post-administration INR. In addition, they found that vitamin K was more often administered orally than intravenousl, even among patients who were bleeding or required imminent invasive procedures, where urgent reversal seemed appropriate. This trend may have been due to concerns about the risk of anaphylaxis associated with IV delivery.
Again, here is Dr. Sweeney:
“Patients receiving IV vitamin K showed a more rapid response to the medication: 44% of patients who received IV medication achieved an INR of less than or equal to 2 within 12 hours, while only 14% of patients who received oral medication achieved this reversal. However, after 48 hours, there was no significant difference between the portion of patients who achieved an INR of less than or equal to 1.5.”
Dr. Ravindra Sarode, who authored an editorial accompanying the study, added:
“This retrospective study alleviates the fear of anaphylaxis that was associated with intravenous vitamin K administration in the past. In fact, at our institution in last 12 years we have not seen a single documented case of anaphylaxis after thousands of doses of intravenous vitamin K use. This has significantly decreased the use plasma for warfarin reversal, in fact, in last 2-3 years I do not recall use of plasma for warfarin reversal in our place.”
We’ll be back on March 30th with another edition of Transfusion News. Thanks for joining us.