Objective : To compare the peak and trough gentamicin concentrations in neonates after a once (ODD) vs. twice daily dosing (TDD) to establish the appropriate dosage for Thai neonates.
Material and Method : Neonates of gestational age > 34 weeks, or body weight > 2000 g, suspected of having bacterial infection were randomized to receive gentamicin intravenously, either 5 mg/kg every 24 hours or 2.5 mg/kg every 12 hours. The peak and trough serum gentamicin levels (SGLs) were measured. Serum creatinine cued nephrotoxicity.
Results : Neonates were evaluated and baseline characteristics between the groups were compared. The ODD and TDD group had a mean gentamicin peak and trough concentration of 10.1 + 3.0 vs. 7.8 + 2.0 μg/ml (p < 0.05) and 1.6 + 1.1 vs. 2.6 + 1.2 μg/ml (p < 0.05), respectively. The peak SGL of > 4 μg/ml was achieved in 100% vs. 96% of the ODD vs. TDD group, respectively. SGL troughs > 2 μg/ml were detected less
often in the ODD group (22% vs. 68%; p < 0.05). Abnormal change in serum creatinine was not observed in either group.
Conclusion : A once dialy dose of gentamicin 5 mg/kg achieved a significantly higher peak SGL and safer trough than a twice-daily dose of 2.5 mg/kg albeit about a quarter of the ODD group had high troughs. A single daily dose of gentamicin 3.5-4 mg/kg/d in Thai neonates should be tested.