Evaluation of gentamicin therapy in newborns at a community hospital and development of simple dosing guidelines

This study evaluated dosing and pharmacokinetics of gentamicin in neonates at a 600-bed community hospital. Pharmacokinetic data were used to predict steady-state gentamicin drug concentration measurements (DCMs) that the original and five simple alternative dosing regimens (2.5 mg/kg q16h, 2.5 mg/kg q18h, 3 mg/kg q24h, 3.5 mg/kg q24h, and 4 mg/kg q24h) would produce. Fifty infants with DCMs were divided into three groups based on gestational age and two weight groups to examine differences in pharmacokinetics, Gentamicin t1/2 was 8.1 (± 3.4) hours, V was 0.54 (± 0.20) L/kg, k was 0.10 (± 0.04) hours-1, and CL was 0.05 (± 0.02) L/h/kg. The percent (n = 50) of infants with DCMs in a therapeutic range-defined as peak concentrations of 4 to 8 mg/L and trough concentrations less than 2 mg/L-were 46%, 59%, 74%, 78%, 64%, and 32% for the original 2.5 mg/kg q16h, 2.5 mg/kg q18h, 3 mg/kg q24h, 3.5 mg/kg q24h, and 4 mg/kg q24h dosing methods, respectively.