[Pharmacokinetic and clinical evaluations of ceftriaxone in neonates and premature infants].

Following a one shot injection with ceftriaxone (CTRX) 10 mg/kg or 20 mg/kg into 23 neonates (1 to 24 days old) including premature infants, plasma levels of CTRX were measured up to 12 hours post-dose in some cases and up to 72 hours post-dose in others and also urinary levels and urinary recovery rates were determined up to 12 hours post-dose. Furthermore, clinical, bacteriological and infection-prophylactic effects of CTRX were evaluated by the intravenous administration with the mean dose of CTRX of 47.7 mg/kg once daily or half the dose twice daily for 9 days on the average into 46 infants (0 to 6 months old) including neonates and premature infants; i.e., 21 cases with actual or suspected bacterial infections for the evaluation of clinical and bacteriological effects and 25 without bacterial infection for the evaluation of prophylactic effects against bacterial infection. The safety of CTRX was evaluated in 53 cases including 7 which were omitted from the efficacy evaluation due to adverse reactions and also in some cases from clinical laboratory parameters. The following is a summary of the results obtained: 1. Following the administration with CTRX 10 mg/kg into each of the neonates 6, 12, 13 and 21 days old (the 21 old one was premature), plasma levels of CTRX in these subjects reached their peaks at 5 minutes post-dose at levels of 59.38, 53.13, 37.50 and 50.00 micrograms/ml, respectively. The peak levels were similar to each other with an exception of the rather low level in the 13 day-old neonate. The plasma half-life times of CTRX in these subjects were 9.762, 7.775, 7.330 and 8.149 hours, respectively: The younger the infant the longer the half-life tended to be except the premature cases. Similarly, the younger the infant the larger the AUC was except for the premature case with the AUC values of 511.169, 324.714, 236.346 and 326.825 micrograms.hr/ml, respectively. The Vds were 0.709, 1.004, 1.316 and 0.696 liters, respectively, and the value for 13 day-old neonate was the largest. Urinary levels of CTRX reached between 42.00 and 298.30 micrograms/ml at some time within 12 hours post-dose in any cases. Urinary recovery rates in 12 hours post-dose were 79.98, 52.00, 56.82 and 60.14%, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)