[Pharmacokinetic-therapeutic studies of ceftriaxone in premature and mature newborn infants].

Ceftriaxone a third generation Cephalosporine exhibits a high degree of antimicrobial activity against the most common pathogens causing life threatening infections in premature and newborn infants. Ceftriaxone was used therapeutically in 16 premature and newborn infants with proven or suspected bacterial infections. Pharmakokinetic investigations were performed during this therapeutic trial. 0.1 ml of blood was taken at 2, 6 and 10 hours after intravenous administration of 50 mg/kg BW Ceftriaxone administered as a single daily bolus injection. Again on day two and four 2 hours after readministration of the same dose, serum concentrations were determined by a biologic test method. With these five samples only, we were able to calculate all clinically relevant pharmakokinetic parameters. There was a high degree of agreement between the experimentally determined and the calculated parameters. Premature infants showed a lower Cmax (115 micrograms/ml) which corresponded to the higher volume of distribution of 44% in this age group. Newborn infants in contrast showed a Cmax of 129 micrograms/ml corresponding to a volume of distribution of 39%. The halflife of elimination was 10.4 and 9.6 hours resp. for premature and mature newborn infants. Cumulation of the drug was seen during the first two days of treatment. A steady state however ensued on day three in both age groups after which no further increase in maximum serum concentrations was seen. Our data suggest, that 50 mg/kg BW once daily given intravenously by bolus-injection or short infusion over 30 minutes constitutes sufficient therapy for serious bacterial infections in premature and newborn infants with susceptible organisms.(ABSTRACT TRUNCATED AT 250 WORDS)