Pharmacokinetic Principles Favours Twice Daily Regimen (BID) of Gentamicin in Paediatric Patients

Abstract

Objectives: Gentamicin is frequently used for management of serious infections in paediatrics, debates exist about once daily (OD) regimen. This study was conducted to investigate the utility of twice daily regimen (BID) in view of pharmacokinetic principles.

Method: 26 patients (age 1month-12years) were enrolled. Serum gentamicin level was determined using an immunoassay; the peak levels were taken 30 min. after the end of infusion and the trough levels just before the next dose. Pharmacokinetic (PK) analysis was based on one compartment model, 1st order elimination and repeated short IV infusion.

Results: Only 44% of the patients showed adequate peak gentamicin levels (6-12μg/ml). Potentially toxic trough levels (>1μg/ml) were observed in two patients. Neonates (1-12month) showed a relatively higher mean gentamicin volume of distribution (Vd), 0.51 ± 0.18 L/Kg vs 0.37 ± 0.13 (p <0.05) in paediatric patients (1-12yr). Half-life in both groups were comparable (about 3h).

Conclusion: Paediatric patients showed high gentamicin Vd and short half-life, therefore BID regimen of 3.5-4mg/kg is more likely to provide peak and trough levels within normal range.