The Effects of the Early and Late Phases of Septic Shock on the Population Pharmacokinetics of Vancomycin.

Pathophysiologic changes in the early and late phases of septic shock affect the pharmacokinetic (PK) parameters, varying dose adjustments may be necessary. This study aimed to create the PK models of vancomycin in the early and late phases of septic shock and to describe the association between the area under the curve from 0 to 24 h (AUC_0-24) and acute kidney injury (AKI). The data from patients with septic shock receiving vancomycin was collected either prospectively or retrospectively. A nonlinear mixed-effects modeling approach was used to develop the PK models. A total of 208 septic shock patients were enrolled and classified into the early (n = 96) and the late phase (n = 112). A two-compartment PK model is the best base model for both phases of septic shock. The model that best predicted the clearance (CL) of both phases was the 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine equation, which was not indexed to body surface area (BSA). Albumin (ALB) was a covariate associated with vancomycin CL only in the late phase. The typical values of CL and volume of distribution (V_d) in the early phase were 1.71 L/h and 68.94 L. In the late phase, CL was 1.65 L/h, and V_d was 66.36 L. The AKI was observed in patients with a high simulated AUC_0-24. The population PK model of vancomycin in the early and late phases of septic shock has been established. The CKD-EPI not indexed to BSA predicts vancomycin CL in both phases. ALB was associated with CL in the late phase.