A prospective observational study of vancomycin trough levels using two different dosing regimens in over 200 neonates found that vancomycin trough levels of less than 10 mg/L were quite common (70% of trough levels were below this level). These suboptimal levels were associated with lower birth weight, lower gestational age and lower post-menstrual age. Other important points emphasized in this article are:
1. In neonates the optimal trough targets are unknown (the current recommendation of trough level greater than 10 mg/L is based on adult regimens).
2. In adults, trough concentrations are a surrogate for the real measure of interest, which is the ratio of the area under the curve 0-24 / minimal inhibitory concentration (goal is to have this ratio at 400 or higher). However, the optimal parameter for vancomycin efficacy in neonates is unknown.