[Pharmacokinetics and clinical evaluation of ceftriaxone in neonates]

A parenteral cephem antibiotic ceftriaxone (CTRX) was studied for its pharmacokinetic features and clinical efficacy and safety in various infections in neonates including premature infants at 11 institutions associated with Japan Perinatal Infection Research Group. The following results obtained are summarized as follows. 1. Following single intravenous bolus injections with 10 and 20 mg/kg of CTRX, serum levels of the drug at 30 minutes post-dose 36-42 micrograms/ml and 46-76 micrograms/ml, respectively, and those at 12 hours post-dose were 10-14 micrograms/ml and 13-21 micrograms/ml, respectively, in a total of 105 neonates. Serum levels detected were on very gentle descending curves. 2. Half-lives (T 1/2) of the drug in serum were significantly prolonged in 0-3 day age groups of both mature and premature infants: it was especially long in premature infants with age of 0-3 days; i.e., 17.1 hours. There was no difference in T 1/2 between the 4-7 day and 8-28 day age groups. 3. Urinary excretion rates were 20-30% in the first 6 hours post-dose and 30-40% in 12 hours post-dose, in 80 neonates examined. 4. Clinical efficacy: Clinical efficacies were evaluated in 112 of 168 enrolled excluding infants with 90 days of age or older, who were treated for prophylaxis and unevaluable cases. The safety was evaluated in 161 of the 168. (1) Demographic background of the 112 cases: The 112 cases were composed of 89 neonates with ages of 28 days or younger, 21 premature infants, 57 males and 55 females. The drug was given to 102 of the cases by intravenous bolus injection, with 81 cases administered twice a day and 97 cases receiving 10-50 mg/kg a day. (2) Efficacy rate in the 112 cases: In 60 cases for whom causative pathogens were identified the efficacy rate was 90.0% in total (excellent: 31/60; good: 23/60); efficacy rates of 87.5% were obtained in 8 cases with purulent meningitis and 90.9% in 11 with septicemia. In 52 with causative pathogen not identified, the efficacy rate was 96.2% in total (excellent: 21/52; good: 29/52). (3) Adverse reaction: Adverse reactions were noted in 14 of the 161 cases where the safety was evaluated (8.7%). These reactions included diarrhea in 11, vomiting in 2 and exanthema in 1. Abnormalities in laboratory test values were observed in 25 of the 152 cases (16.4%). They included eosinophilia in 14, elevated GOT in 4 and thrombocytosis in 3 etc.(ABSTRACT TRUNCATED AT 250 WORDS)