Abstract
<title>Abstract</title> <p> Background Augmented renal clearance (ARC) can increase vancomycin (VCM) clearance. Although Japanese guidelines recommend administering a VCM dose of 20 mg/kg every 12 h in patients with normal renal function, more frequent high-dose administration of VCM (15–20 mg/kg every 8 h) is recommended during ARC. However, knowledge regarding the pharmacokinetics of VCM during ARC in Japanese patients is insufficient. This report describes three ARC cases that exhibited variable responses to the recommended VCM dosing regimens. Case presentation Case 1 involved a male patient in his 50s whose urinary creatinine clearance (CrCl) during therapeutic drug monitoring (TDM) was 163.6 mL/min/1.73 m². The steady-state area under the time–concentration curve (AUC <sub>ss</sub> ) during TDM was 573.1 µg·h/mL for 20 mg/kg administered every 12 h, 664.8 µg·h/mL for 15 mg/kg administered every 8 h, and 859.7 µg·h/mL for 20 mg/kg administered every 8 h. Case 2 involved a male patient in his 40s whose urinary CrCl during TDM was 146.6 mL/min/1.73 m². The AUC <sub>ss</sub> values during TDM were 562.8 µg·h/mL for 20 mg/kg administered every 12 h, 633.5 µg·h/mL for 15 mg/kg administered every 8 h, and 844.2 µg·h/mL for 20 mg/kg administered every 8 h. Case 3 involved a male patient in his 30s whose urinary CrCl during TDM was 224.2 mL/min/1.73 m². The AUC <sub>ss</sub> values during TDM were 403.5 µg·h/mL for 20 mg/kg administered every 12 h, 453.9 µg·h/mL for 15 mg/kg administered every 8 h, and 605.2 µg·h/mL for 20 mg/kg administered every 8 h. Conclusions Among the patients with ARC, two with lower urinary CrCl had an AUC <sub>ss</sub> exceeding 600 µg·h/mL, which is a risk factor for nephrotoxicity, with VCM administered at 15–20 mg/kg every 8 h. Conversely, for patients with higher urinary CrCl, the AUC <sub>ss</sub> is expected to be approximately 400–600 µg·h/mL for VCM administered at 15–20 mg/kg every 8 h. Therefore, in Japanese patients with ARC, uniform VCM dosing at 15–20 mg/kg every 8 h may exceed the upper limit of the AUC <sub>ss</sub> , and the VCM dose may need to be tailored according to ARC severity in this patient population. </p>