Empiric vancomycin dosing in neonates: Relationship between initial dose and 24 h area under the curve/minimum inhibitory concentration ratio

Abstract

Background: Vancomycin is used for treating coagulase-negative staphylococcus infections in neonates. However, concerns about the appropriate empirical dosing required for optimal efficacy, still remain. Aim: To assess the relationship between the initial doses of vancomycin used in a Neonatal Intensive Care Unit (NICU) with the possibility of achieving therapeutic target of AUC024h/MIC > 400 µg/h/ mL. Methods: Retrospective and descriptive study carried out between February 2016 and March 2018. All neonates treated with vancomycin for suspected/proven Gram-positive infection and with at least one trough serum concentration level were included. Probability of target attainment (PTA) was evaluated through resampling of AUC and MIC values. Results: Final dataset included 38 patients and 49 trough vancomycin levels; 94.7% of these cases (n = 36) were confirmed Grampositive infections. The median AUC/MIC values for the trough values vancomycin < 10 µg/mL group and for the ≥ 10 µg/mL group were 327 (IQR 174-395) and 494 (IQR 318-631) respectively (p = 0.035). Current empirical dosing strategy has a 47.7% PTA (AUC/MIC > 400) when taking institutional MICs into account. Conclusions: It is not possible to assure achieving a AUC/MIC > 400 µg/h/mL when considering institutional sensibilities. Current empiric dosing strategies should be reconsidered and further investigation needs to be done to help determine the appropriate empirical dosing required for optimal efficacy in neonates.