Gentamicin pharmacokinetics in Thai neonates: recommendation for a dosing guideline.

A pharmacokinetic study of gentamicin was performed on 32 Thai neonates. After a single intravenous infusion of gentamicin at 2.5 mg/kg body weight, blood samples were collected at 0.5 and 12 hours. Serum gentamicin concentrations were determined with use of fluorescence polarizing immunoassay. None of the neonates with < 28 weeks post conceptional age (PCA), contrary to most of the more mature neonates, achieved the recommended therapeutic peak concentrations. The volume of distribution (Vd) and elimination half-life (T1/2) of gentamicin were found to reversely correlate with the PCA, with significantly larger Vd and longer T1/2 values observed among the premature neonates. Our findings were similar the results previously reported in Caucasians, and thus strongly indicated the necessity of gentamicin dosage adjustment among Thai neonates according to their PCA. A gentamicin dosing guideline for Thai neonates has been proposed, nonetheless, with higher doses and longer dosing intervals recommended among premature neonates.