Elevated INR in a COVID-19 patient after concomitant administration of favipiravir and warfarin: A case report.

WHAT IS KNOWN AND OBJECTIVE: Favipiravir is a promising treatment candidate for managing coronavirus disease 2019 (COVID-19). Warfarin has many drug interactions, but no interactions with favipiravir have been reported. CASE SUMMARY: Our patient was taking warfarin for deep vein thrombosis. The international normalized ratio (INR) was stable (1.65 to 2.0); however, it increased to 4.63 after administering favipiravir. The patient had no other factors justifying this change. WHAT IS NEW AND CONCLUSION: Favipiravir and warfarin might have previously unidentified drug interactions that elevated the INR. Therefore, INR must be closely monitored when they are concomitantly administered in COVID-19 patients.

Relationship between hemoglobin levels and vancomycin clearance in patients with sepsis.

PURPOSE: It is important to accurately estimate accurate vancomycin (VCM) clearance (CLvcm) for appropriate VCM dosing in the treatment of patients with sepsis. However, the pathophysiology of sepsis can make CLvcm prediction less accurate. Clearance of hydrophilic antibiotics is disturbed by organ dysfunction, and hemoglobin levels are negatively correlated with sequential organ function assessment scores. We investigated whether hemoglobin levels are associated with CLvcm in sepsis patients. METHODS: We performed a retrospective cohort study of patients treated with VCM in the Emergency and Critical Care Center of Nihon University Itabashi Hospital between 2005 and 2015. We enrolled 72 patients after exclusion of patients who received renal replacement therapy or surgery, had a change in hemoglobin levels more than 2 g/dL or received an erythrocyte infusion during the interval between initial VCM administration and measurement of initial trough levels, had a serum baseline creatinine level of ≥ 2 mg/dL, or were under 18 years old. RESULTS: Enrolled patients consisted of 13 non-sepsis patients and 59 sepsis patients. In sepsis patients, although CLvcm was correlated with CrCl in HGB ≥ 9 group as well as in non-sepsis patients, its correlation was not observed in HGB < 9 group. Hemoglobin levels were correlated with CLvcm in sepsis patients but not in non-sepsis patient. Multiple linear regression analysis also indicated that lower CLvcm was associated with lower hemoglobin and CrCl. CONCLUSION: Lower hemoglobin levels influence a relationship between CLvcm and CrCl in sepsis patients. We propose that VCM dosing should be adjusted for hemoglobin levels in sepsis patients.