Document Type


Date of Original Version



Pharmacy Practice


Background: Supratherapeutic warfarin therapy can lead to major bleeding events if left uncorrected. The effects of warfarin can be reversed with exogenous vitamin K. Guidelines recommended use of vitamin K to reverse warfarin therapy based on INR level and presence of patient bleeding. The objective of this study is to examine and evaluate the appropriateness of vitamin K (phytonadione) use at the Providence VA Medical Center (PVAMC) when administered orally or intravenously for the purpose of reversing an elevated international normalized ratio (INR) caused by warfarin therapy. The primary outcome was the rate of adherence to the 2012 CHEST guidelines.

Methods: Study design: retrospective electronic chart review. Vit K administration deemed appropriated if INR was between 4.5 and 10 with evidence of bleeding or INR >10 with no evidence of bleeding or any warfarin-associated major bleeding. Inclusion criteria: admitted for any reason from January 1, 2017 – December 31, 2019 and active outpatient warfarin prescription at the time of vitamin K administration, and received vitamin K either orally or intravenously, at any dose or frequency. Patients were excluded if prescribed a DOAC (ie. apixaban, dabigatran, edoxaban, or rivaroxaban), received vitamin K alone for any reason other than for warfarin reversal such as perioperative use, hepatic disease (i.e. cirrhosis, hepatitis, etc.), or had a contraindication to vitamin K such as allergy or anaphylaxis. Descriptive statistics were employed.

Results: 152 individual vitamin k administrations were screened and 70 were included for data analysis. Twenty-seven percent of vitamin k administrations were found to be appropriate (n = 19). Ninety-four percent of patients were male. The most common warfarin indications were atrial fibrillation (78%) and venous thromboembolism (16%). Mean INR at the time of vit K administration was 4.9 overall and was higher in the appropriate vs inappropriate administration group (6 vs 4.4, respectively). Mean INR was higher for oral vs parenteral doses (5.2 vs 3.98, respectively). Major and minor bleeding rates were 58% and 21% in the appropriate administration group and 0% (n=0) and 31% (n=16) in the inappropriate group, respectively.

Conclusions: According to the 2012 CHEST guidelines, the majority of vitamin K doses administered and recorded for warfarin reversal at the PVAMC during the study period were found to be inappropriate. Strategies for improving appropriate use at this institution such as implementation of a vitamin K administration protocol and/or provider education should be explored. Further investigation is needed on vitamin K use in patients not prescribed warfarin for anticoagulation.