Reply

Abstract

We appreciate the comments of Hahn and Vinks and their active interest in the optimization of vancomycin dosing practices in children. The authors share results from a recent investigation into the complex relationship between pediatric vancomycin dosing, trough attainment and AUC, which we commend. We agree that the target vancomycin trough for an individual child that predicts AUC > 400 will vary based on age, size, maturation, kidney function, dosing interval, etc. More personalized approaches to vancomycin dosing including the use of individual Bayesian estimates of vancomycin clearance to predict AUC would be helpful to optimize target exposures in children. Unfortunately, this approach to predict AUC is not always available to providers, and the trough instead is used to guide dosing. Hahn and Vinks report that among 6 patients with trough concentrations in the 8–10 mcg/mL range, only 67% achieved the desired AUC >400, whereas our model and simulation analysis predicted that over 90% of children with troughs in this range would achieve the desired AUC. Although our study was only a simulation study, we urge the use of caution in drawing conclusions based on such a small sample of 6 subjects, especially given the wide range of age (1–17 years) and dose (45–102 mg/kg/day) used. Clearly, larger sample sizes are needed. We wish to reiterate, however, that the main conclusion to be derived both from our study and the work of Hahn and Vinks is that trough goals in the range of 15–20 mcg/mL are unnecessary for most children. Adam Frymoyer, MD Department of Pediatrics Stanford University Standford, CA Adam L. Hersh, MD, PhD Department of Pediatrics University of Utah Salt Lake City, UT