Abstract

National treatment guidelines for invasive methicillin-resistant Staphylococcus aureus (MRSA) infections recommend targeting a vancomycin 24-hour area under the curve (AUC24)/MIC >400. The range of vancomycin trough concentrations that best predicts AUC24 >400 in neonates is not known. This understanding would help clarify target trough concentrations for neonates when treating MRSA. A retrospective chart review from a level III neonatal intensive care unit was performed to identify neonates treated with vancomycin over a 5-year period. Vancomycin concentrations and clinical covariates were utilized to develop a one-compartment population pharmacokinetic model and examine relationships between trough and AUC24 in study neonates. Monte Carlo simulations were performed to examine the effect of dose, post-menstrual age (PMA), and serum creatinine on trough and AUC24 achievement. A total of 1702 vancomycin concentrations from 249 neonates were available for analysis. The median [interquartile range] PMA was 39 wks [32-42 wks] and weight was 2.9 kg [1.6-3.7kg]. Vancomycin clearance was predicted by weight, PMA, and creatinine. At a trough of 10 mg/L, 89% of study neonates had an AUC24 >400. Monte Carlo simulations demonstrated that troughs ranging from 7-11 mg/L were highly predictive of an AUC24 >400 across a range of PMA, serum creatinine, and vancomycin doses. However, a trough =10 mg/L was not readily achieved in most simulated subgroups using routine starting doses. Higher starting doses frequently resulted in troughs >20 mg/L. A vancomycin trough of ~10 mg/L is likely adequate for most neonates with invasive MRSA infections based on AUC24 considerations. Due to pharmacokinetic and clinical heterogeneity in neonates, consistently achieving this target vancomycin exposure with routine starting doses will be difficult. More robust clinical dosing support tools are needed to help clinicians with dose individualization.

View details for DOI 10.1128/AAC.03620-14

View details for PubMedID 25136027