Dosing of Vancomycin in Neonates: On Target for the Therapeutic Range?

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BACKGROUND Achieving therapeutic vancomycin concentrations in neonates is an ongoing challenge. Initial dosage is primarily based on weight but can also include consideration of gestational age. Therapeutic drug monitoring limits the potential for toxicity, treatment failure, and the development of bacterial resistance. This study examined the frequency of achieving an appropriate therapeutic trough concentration based upon the initial dosage. METHODS A multicenter retrospective study of 626 neonates, birth weight >1500g (0-27 days) who received vancomycin between 01/2006 and 09/2011 was performed using a large electronic health database. For each patient, the first vancomycin trough level was used to determine whether vancomycin blood concentrations fell into the therapeutic range (defined as 10-20 μg/mL). Neonates without evaluable vancomycin trough levels, or renal impairment were excluded from analysis. Weights were converted to z-scores using Epi Info 7, which was limited to infants with a birth weight >1500 g, and statistical analysis was performed in Prism 6 (Graphpad). These data were not complete before December 5, 2012. RESULTS Evaluable trough and creatinine levels were available for 402 patients (64% male). 185 patients (46%) had a trough concentration outside therapeutic range, 32% (n=127) below 10 μg/mL, and 14% (n=58) above 20 μg/mL. There was no statistical difference between males and females by age, number of vancomycin doses given, weight, or trough levels. However, the dose of vancomycin administered was higher for males with a median of 47.0 mg/dose (95% confidence interval (CI), 38.0-60.0) than females with 45.0 mg/dose (95% CI,35.0-53.0); p <0.02. CONCLUSION This study demonstrates that the standard dosing regimens for vancomycin in neonates results in trough levels outside of therapeutic range nearly half of the time. These results highlight the need for more effective strategies in vancomycin dosing in neonates.


Presented at the 114th Annual Meeting of the American Society for Clinical Pharmacology and Therapeutics.