Correlation of a Vancomycin Pharmacokinetic Model and Trough Serum Concentrations in Pediatric Patients

Background: Vancomycin trough concentrations specific to pediatric patients have yet to be validated that achieve an area under the curve (AUC) over 24 hours to minimum inhibitory concentration (MIC) ratio >= 400. The primary objective of this study was to validate a pharmacokinetic model in a pediatric hospital and determine the correlation between a calculated AUC/MIC ratio and measured trough vancomycin concentration. Methods: A retrospective evaluation of patients aged 3 months to 18 years prescribed vancomycin at a pediatric hospital between January 2012 and June 2013. The correlation between patient-specific AUC/MIC and measured vancomycin trough concentration was assessed. Results: Forty pediatric patients with 40 vancomycin trough concentrations and documented Staphylococcus aureus cultures were included in the study. Median age was 8.5 (interquartile range, 2-14.3) years, median weight 28.7 (range, 14-50.2) kg, and mean baseline serum creatinine 0.51 +/- 0.3 mg/dL. The mean daily dose of vancomycin prescribed was 58 +/- 13.8 mg/kg/d. The mean vancomycin trough concentration was 11 +/- 5.5 mcg/mL, and the mean AUC/MIC was 534 +/- 373. No correlation was found between trough concentration and AUC/MIC (r(2) = 0.082, p = 0.07). Conclusions: This study validates the clinical applicability of a pharmacokinetic model for calculating vancomycin clearance to determine patient-specific AUC over 24 hours in pediatrics. Trough concentrations associated with proposed therapeutic AUC/MIC ratios were lower than reported in the adult population. Further research is needed to determine if AUC/MIC, trough concentration, or both is best for monitoring therapeutic efficacy of vancomycin in pediatrics.