Cefazolin-Associated INR Elevation: A Case Report

Purpose To describe a case of significantly elevated international normalized ratio (INR) in a patient on apixaban receiving treatment with intravenous cefazolin in the setting of coronavirus disease 2019 (COVID-19) infection and malnutrition. A 74-year-old male patient on apixaban receiving cefazolin for osteomyelitis in the setting of COVID-19 and poor nutritional intake presented with internal jugular tunneled catheter site bleeding and an INR of greater than 22.5. Laboratory abnormalities and bleeding concerns were successfully managed with vitamin K and changing antimicrobial therapy from cefazolin to daptomycin. Follow-up labs one week later demonstrated a sustained improvement in coagulopathy. Conclusion INR prolongation believed to be secondary to cefazolin can be effectively managed with administration of vitamin K and conversion of antimicrobial therapy to an alternative agent.