[Pharmacokinetic and clinical evaluations on ceftriaxone in neonates and premature infants]

Ceftriaxone (CTRX) was clinically evaluated and its pharmacokinetics studied in neonates and premature infants, and the results obtained are summarized as follows. 1. Average blood levels of CTRX after intravenous administration of 10 mg/kg in 3 neonates with birth weights of 2,500 g or more were 45.32 mcg/ml at 15 minutes, 28.91 mcg/ml at 1 hour, 15.76 mcg/ml at 6 hours, and 16.28 mcg/ml at 12 hours, and the half-life was 9.93 hours. The half-life in a newly born premature infant (less than 1 day) was 28.90 hours, and in a premature infant 6 days old it was 12.90 hours. 2. Average blood levels after intravenous administration of 20 mg/kg to 2 neonates aged 0 and 3 days with birth weights of 2,500 g or more, were 129.7 mcg/ml at 15 minutes, 60.94 mcg/ml at 1 hour, 32.04 mcg/ml at 6 hours, and 24.23 mcg/ml at 12 hours, and the half-life was 8.95 hours. The half-life in a newly born premature infant (less than 1 day) was 20.70 hours. 3. Urinary recovery rates of CTRX in 12 hours after intravenous administration of 10 or 20 mg/kg to 6 neonates aged 0 to 3 days (including premature infants) ranged from 13.8 to 50.6%. 4. Clinical efficacies of CTRX were excellent or good in 3 of 4 neonates including infants suspected of having infections (efficacy rate: 75%). 5. As a side effect, diarrhea was noted in 1 case.