Pharmacokinetic approach for optimizing gentamicin use in neonates during the first week of life

INTRODUCTION: Gentamicin is an essential drug for the treatment of sepsis in neonates. The current work aims to optimize the use of gentamicin in neonates during the first week of life. MATERIALS AND METHODS: The study was done at King Abdul-Aziz university hospital. Seventy-three neonates who received gentamicin 4-5 mg/kg and dosing interval at 24-48 hr were enrolled. Peak and trough serum levels of gentamicin were determined by immunoassay. Pharmacokinetic parameters were estimated assuming one compartment model and first order elimination kinetic. Analysis of variance was used to test the difference between means using Statistical Package for the Social Sciences (SPSS) Version 13. RESULTS: About 73% of the patients attained peak gentamicin level within therapeutic range (6-12μg/ml), while 12% showed potentially toxic trough level (>2 μg /ml). The incidence of trough level was higher among patients receiving the drug every 24 hr. There was no clear correlation between high trough level and serum creatinine. High volume of distribution (Vd) of gentamicin (0.40-0.45) L/kg was observed. Neonates with proven sepsis showed higher mean Vd. Those with extremely low birth weight showed significantly longer half life of 11.5 h. Other neonates showed half life of (8-9) hr. CONCLUSIONS: Gentamicin dose of 4.5 mg/kg every 36 hr is recommended as simple empirical regimen during the 1(st) week of life for neonates with normal or LBW and every 48 hr for those with ELBW.