Multidose pharmacokinetics of vancomycin were studied in 15 infants with 
gestational age less than 36 weeks and suspected or confirmed Staphylococcus 
epidermidis infections. Postconceptional age (PCA) at the time of the study 
ranged from 26 to 44 weeks. Vancomycin individual doses ranged from 6.7 to 10.6 
mg/kg and were infused over 60 min. Five postinfusion samples were obtained in 
13 infants, while 4 samples were obtained in 2 patients. Vancomycin 
pharmacokinetic parameters were determined by fitting the data to a 
two-compartment model using a weighted least-squares nonlinear regression 
method. Mean vancomycin body clearance (CL), volume of distribution (Vdss) and 
terminal elimination half-life were 1.37 ml/min, 0.58 liters and 5.6 h, 
respectively. When standardized for patient weight, the CL and Vdss values were 
1.07 ml/min/kg and 0.48 liters/kg, respectively. The CL (ml/min/kg) was strongly 
inversely correlated with the serum creatinine (r = -0.82), while a weaker but 
significant association was noted with PCA (r = 0.41). These data suggest that 
in sick infants, in addition to the PCA, serum creatinine should be considered 
when determining the initial vancomycin dosing regimen.