[Pharmacokinetic, bacteriological and clinical studies of ceftizoxime in neonates].

Pharmacokinetic, bacteriological and clinical studies of ceftizoxime (CZX) were performed in neonates. 1. Serum concentrations and urinary excretion of CZX were investigated in 12 neonates ranging ages from 1 to 27 days (gestational age, 35-41 weeks; birth weight, 2,150-4,030 g) and 2 infants ranging ages from 55 to 57 days (gestational age, 39-40 weeks; birth weight, 2,320-2,650 g). Each of the subjects was given a single intravenous dose of 20 mg/kg by one shot. Serum concentrations of CZX in the neonates were 24.9-53.7 micrograms/ml at 1/4 hour after intravenous injection, with an average of 40.6 +/- 7.6 micrograms/ml. Serum half-lives of CZX were 1.32-4.75 hours and averaged 2.60 +/- 1.06 hours. Serum concentrations ranged from 2.01 to 14.6 micrograms/ml at 6 hours after injection with an average of 7.70 +/- 3.89 micrograms/ml. In the 2 infants, serum concentrations were 42.0 and 46.2 micrograms/ml at 1/4 hour (average: 44.1 +/- 3.0 micrograms/ml), and 2.91 and 5.04 micrograms/ml at 6 hours after injection (average: 3.98 +/- 1.51 micrograms/ml). Half-lives were 1.54 hours in 1 infant and 1.93 hours in the other (average: 1.74 +/- 0.28 hours). Furthermore, 6-hour urinary recovery rates were 28.5-71.7% (average: 49.3 +/- 12.8%) in the neonates and 42.1-55.5% (average: 48.8 +/- 9.5%) in the infants. The above results suggest that the following 3 points are accepted; 1) peak serum concentrations (at 1/4 hour) in neonates were similar to those in infants and older children irrespective of age (days after birth). 2) Serum half-lives of CZX in neonates shortly after birth were 4 or 5 times longer than those in older children, but decreased rapidly with the advance of day-ages. The half-life in neonates of 2 weeks of age or so became shorter to about twice the normal value in infants. Furthermore, half-lives of the drug in those at an age of the first half of infancy were similar to those in older children. 3) The urinary excretion rates tended to be somewhat low with neonates soon after birth, but became very similar to those in infants and older children at a relatively early stage.(ABSTRACT TRUNCATED AT 400 WORDS)