Kinetics and dose calculations of ampicillin and gentamicin given as continuous intravenous infusion during parenteral nutrition in 88 newborn infants.

Ampicillin and gentamicin were administered continuously intravenously to 88 newborn infants using individually calculated dosages. For infants with a mean value of plasma clearance of the antibiotics, it was calculated that the serum ampicillin and gentamicin concentrations would be between 35-55 and 3-5 micrograms/ml, respectively, using the dosages for intermittent treatment. These dosages are therefore recommended as fixed dosages for continuous intravenous infusion initiated by a bolus dosage. Serum gentamicin concentration should be assayed about three half-lives after start of infusion and the dosage adjusted for values outside 3-5 micrograms/ml.