Comparison of Measured Trough Values after Deriving the Initial Dose Setting of Vancomycin with a Conventional Computer Software and a Nomogram Based on the Revised Japanese 2016 Therapeutic Drug Monitoring Guidelines for Antimicrobial Agents

Background: Due to the relatively high renal toxicity of vancomycin injection (VCM), setting an initial dose that achieves a trough that ranges between 10 and 20 μg/mL on day 3 is important to ensure safety and minimize side-effects, especially for patients with low renal function. To address these issues, the revised 2016 Therapeutic Drug Monitoring (TDM) Guidelines for Antimicrobial Agents (GL2016) proposed the use of a renal function-based, estimate glomerular filtration rate (eGFR) nomogram for setting the dose of VCM in Japan. Methods: Our hospital introduced the use of the GL2016 in September 2016 for the patients administered VCM. After setting the initial VCM dose using 1) a conventional VCM analysis software and 2) the GL2016 eGFR nomogram, the measured trough values on day 3 were compared and evaluated in this study. Results: With the VCM analysis software, the mean measured trough value in the a-total group (n = 53) was 12.8 ± 4.7 μg/mL. With the eGFR nomogram, the mean measured trough value in the b-total group (n = 13) was 9.6 ± 4.6 μg/mL. However, when the different severities of renal function were compared, the mean measured trough value was more significantly lower in the b-1 group than in the a-1 group among subjects with G2 and above (eGFR ≥ 60 mL/min/1.73 m2), but it was similar between the a-2 group and the b-2 group among subjects with G3 and below (eGFR < 60 mL/min/1.73 m2). The proportion of subjects reaching the various trough ranges shows similar tendency. Conclusions: These data suggested that the measured trough value on day 3 was generally lower when the initial dose was established using the eGFR nomogram based on the GL2016, and this was especially prominent among patients with normal renal function. As for subjects with low renal function, the trough values were relatively high while ensuring safety.