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

@entity1 @entity8933 @entity8934
Pharmacokinetic, bacteriological and clinical studies of @entity8933 ( @entity8934 ) were performed in neonates. 1. Serum concentrations and urinary excretion of @entity8934 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 @entity1 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 @entity8934 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 @entity8934 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 @entity1 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 @entity1 . 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 @entity1 and older @entity1 irrespective of age (days after birth). 2) Serum half-lives of @entity8934 in neonates shortly after birth were 4 or 5 times longer than those in older @entity1 , 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 @entity1 . Furthermore, half-lives of the drug in those at an age of the first half of infancy were similar to those in older @entity1 . 3) The urinary excretion rates tended to be somewhat low with neonates soon after birth, but became very similar to those in @entity1 and older @entity1 at a relatively early stage.(ABSTRACT TRUNCATED AT 400 WORDS)
