title: Vitamin K dosing to reverse warfarin based on INR, route of administration, and home warfarin dose in the acute/critical care setting.
abstract: BACKGROUND
  Vitamin K is commonly used for reversal of anticoagulation of warfarin. However, the optimal dose and route of vitamin K that does not increase the duration of bridging therapy is unknown.
  
  
  OBJECTIVE
  To determine factors influencing the extent and rate of INR reversal with vitamin K in the acute/critical care setting.
  
  
  METHODS
  This was a chart review of 400 patients who received vitamin K for reversal of warfarin effects between February 2008 and November 2010. Data collected included international normalized ratios (INRs) 12 hours, 24 hours, and 48 hours prior to vitamin K administration; intravenous or oral vitamin K dose; and whether or not fresh frozen plasma (FFP) was administered.
  
  
  RESULTS
  Intravenous vitamin K reduced INR more rapidly than oral vitamin K (5.09, 1.91, 1.54, and 1.41 vs 5.67, 2.90, 2.14, and 1.58) at baseline, 12, 24, and 48 hours, respectively. The dose of vitamin K (p < 0.001), route of administration (p < 0.001), and baseline INR (p < 0.001) influenced subsequent INR values. The INR reduction was similar for intravenous vitamin K doses 2 mg or greater. Home warfarin dose did not affect INR responses to intravenous (p = 0.27) or oral vitamin K (p = 0.98). FFP did not influence INR values at 48 hours. Although longer anticoagulation bridge therapy seemed to be associated with higher vitamin K doses, the incidence (p = 0.63) and duration (p = 0.61) were not significant.
  
  
  CONCLUSIONS
  Vitamin K dose, route, and initial INR influence subsequent INR values. INR reduction is similar for intravenous vitamin K doses of 2 mg or greater. Preadministration of FFP does not alter INR values at 48 hours or more after vitamin K administration.
authors.affiliation: Midwestern College of Pharmacy Glendale, Glendale, AZ, USA.
authors.forename: Laura V
authors.initials: LV
authors.lastname: Tsu
authors.forename: J Erin
authors.initials: JE
authors.lastname: Dienes
authors.forename: William E
authors.initials: WE
authors.lastname: Dager
mesh_terms: D061605:Administration, Intravenous; D000284:Administration, Oral; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects / Q000037:antagonists & inhibitors*; D000933:Antifibrinolytic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D015331:Cohort Studies; D003422:Critical Care; D004305:Dose-Response Relationship, Drug; D005260:Female; D006699:Home Care Services; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D010949:Plasma; D012189:Retrospective Studies; D013997:Time Factors; D014812:Vitamin K / Q000008:administration & dosage / Q000627:therapeutic use*; D014859:Warfarin / Q000008:administration & dosage / Q000009:adverse effects / Q000037:antagonists & inhibitors*
chemical_list: D000925:Anticoagulants; D000933:Antifibrinolytic Agents; D014812:Vitamin K; D014859:Warfarin