[Kinetics of tobramycin in newborn infants in intensive care]

Maximal and minimal tobramycin concentrations were studied in 16 preterm and 4 fullterm neonates on the last day of a four-day course of tobramycin (infusion of 2 mg/kg twice a day). Maximal concentrations were under 6 mg/l in all patients and minimal concentrations were above 2 mg/l in one-third of the preterm babies. Next, tobramycin pharmacokinetic parameters were studied in 4 fullterm and 4 preterm neonates following a first infusion of 2 mg/kg. Half-life was 4 hours in term babies and 7.75 hours in preterm babies. Mean clearance was 0.118 l/h/kg and 0.06 l/h/kg in fullterm and preterm babies respectively (significant difference). Our results show that the 2 mg/kg dosage is too low and that, in preterm neonates, the 12-hour interval between infusions is too short.