Kinetics of gentamycin in premature infants with a low birth weight during the first four days of postnatal life

: The authors investigated in a group of 19 premature neonates with a low birthweight (0.65-2.1 kg) during the first four days of postnatal life the pharmacokinetics of gentamycin after indicated administration of 2 mg/kg of the antibiotic by the i.v. route by a 30-minute infusion in 18-hour intervals. Serum concentrations of gentamycin were assessed by immunoassay 0.5 hours before administration and then 0.5, 5.5, 11.5 and 17.5 hours after the 5th infusion, i.e. in a steady state. The maximum serum concentrations detected 0.5 hours after the completed infusion exceeded 10 mg/l in 21% of the neonates, while the minimal concentrations of the antibiotic before the next administration were above 2 mg/l in 42% of the infants. The calculation of pharmacokinetic parameters according to the one-compartment model revealed considerable interindividual differences of all values. The authors consider particularly important the low clearance value of the antibiotic (30.24 +/- 14.55 ml/kg.hour-1) which may lead to cumulation of gentamycin and its toxic action. Gentamycin administration to premature neonates should be associated with monitoring of serum concentrations of the drug which would make individual adjustment of the dosage possible.