Pharmacokinetics of amikacin in premature neonates at Pramongkutklao Hospital

Abstract

Introduction : Amikacin has wide inter and intra-patient pharmacokinetic variabilities. Nevertheless, the pharmacokinetics of amikacin in premature neonates has never been studied in Thailand.

Objective : To study the pharmacokinetics of amikacin in Thai premature neonates.

Setting : Pramongkutklao Hospital

Research design : A prospective study

Patients : Premature neonates with suspected infection at the Neonatal Intensive Care Unit, Pramongkutklao Hospital during the 8-month period.

Methods : Thirty-seven premature neonates, whose gestational age were under 30 weeks, 31-33 weeks and 34-36 weeks, were given amikacin as an empirical treatment by intravenous infusion for 30 minutes at the dose of 18 mg/kg every 48 hours, 16 mg/kg every 48 hours and 15 mg/kg every 24 hours, respectively. Peak concentration was measured at 30 minutes after complete infusion; the second concentration was measured at either 18^th hours or 36^th hours after administration depending on the dosing interval of each patient, while trough concentration was derived from calculation.

Results :  Mean peak concentration at steady state of neonates with gestational Conclusion age not greater than 30 weeks, 31-33 weeks and 34-36 weeks were 28.49±8.63, 24.22±5.99 and 24.91±5.73 ng/ml, respectively. While mean trough concentration at steady state of neonates with gestational age not greater than 30 weeks, 31-33 weeks and 34-36 weeks were 1.75 ± 1.32, 1.16 ± 2.13 and 2.21 ± 1.20 ng/ml, respectively. Mean peak and trough concentration were not significantly different among the groups (p > 0.05). Besides, the mean peak concentration of every group was within the desired therapeutic range (20-30 pg/ml) and mean trough concentration of every group were not greater than the desired range (2-5 pg/ml). Elimination rate constant and clearance of amikacin were significantly different among the groups and it was also in good proportional correlation with their gestational age (p < 0.05).

Conclusion : Pharmacokinetics parameters of amikacin in Thai premature neonates are similar to data previously published from other countries. The dosage regimen of amikacin used in premature neonates at Phramongkutklao Hospital were mostly within the range of peak and trough in therapeutic levels.