Effects of co-administration of ibuprofen-lysine on the pharmacokinetics of amikacin in preterm infants during the first days of life.

The aim of this study was to assess the effects of intravenous co-administration of ibuprofen-lysine on the pharmacokinetics of amikacin during the first days of life in preterm infants. The pharmacokinetics of amikacin were retrospectively calculated in a cohort of 73 neonates (gestational age <31 weeks) who received either ibuprofen-lysine or placebo following inclusion in the multicentre ibuprofen prophylaxis study. Assuming a one-compartment model with instantaneous input and first-order output, there was no significant difference in the median distribution volume (0.63 vs. 0.59 liters/kg), but the median serum half-life (16.4 vs. 12.4 h) of amikacin was significantly longer (p <0.02), and the clearance (0.36 vs. 0.6 ml/kg/min; p <0.005) of amikacin was significantly lower in infants who received ibuprofen-lysine. We conclude that the time interval between consecutive amikacin administrations should be prolonged, if ibuprofen-lysine is co-administered.