Monitoring of gentamicin blood level in one-week-of-life neonates admitted to a special care nursery ward

Aims:Gentamicin is routinely used in neonates as an empirical antibiotic for suspected sepsis at a dose of 4.0 mg/kg, either 24 or 36 hourly based on premenstrual age. Regularly, therapeutic drug monitoring is performed. This study was conducted to determine gentamicin blood level in one-week-of-life neonates on 4 mg/kg treatment.Methods:Neonates who received gentamicin in a special care nursery ward were identified from the records retrospectively. The included subjects were neonates between 3 and 7 days old treated with gentamicin for at least three days. Admission diagnoses, dosing protocol (including dosage, the timing of the doses, and timing of blood samples) and measured gentamicin trough and peak levels were recorded.Results:A total of 290 neonates met the inclusion criteria (male: 57.6%). Over 30% of the subjects treated with gentamicin experienced potential toxicity with trough levels above 1.0 μg/mL, and 15.9% of them had sub efficacy of the drug (peak level below 5 μg/mL). Six neonates had trough levels above 2.0 μg/mL. The percentage of potential toxicity was higher in subjects with presumed sepsis, in those with bodyweight between 2.5-2.99 kg and with 24-hour dosing interval.Conclusions:We propose a trough-only monitoring protocol in non-critically ill neonates, as the practice of monitoring pre and post often necessitate additional blood sampling. The decision of not determining the peak levels routinely can be based on the outcome that gentamicin dosage of 4.0 mg/kg likely provides peak levels in desired range without any added risk of toxicity.