[Pharmacokinetics and clinical studies on flomoxef in neonates and premature infants. A study of flomoxef in the perinatal collaboration research group]

Abstract

We investigated pharmacokinetics and clinical effects of flomoxef sodium (6315-S, FMOX) in neonates and premature infants. These results are summarized as follows: 1. Pharmacokinetics (1) Plasma concentration (Ct) and half-lives (T1/2) were determined upon after intravenous one-shot injection (i.v.) of FMOX to neonates of different day-age groups (0-3 (n = 25), 4-7 (n = 18), 8-28 (n = 32) days of birth). At a dose of 10 mg/kg. i.v., mean C30 (30 minutes concentration) values were 21.2, 21.8 and 21.3 micrograms/ml, respectively, in the different groups mentioned above, and the mean T1/2 values were 3.37, 1.85 and 1.63 hours. At 20 mg/kg i.v., mean C15 (15 minutes concentration) values were 54.4, 51.4 and 50.7 micrograms/ml, and mean T1/2's were 2.99, 2.32 and 1.79 hours, respectively. At a dose of 40 mg/kg i.v., mean C15 values were 104.0, 95.9 and 99.2 micrograms/ml, and the mean T1/2's were 3.40, 1.20 and 1.80 hours, respectively. (2) Plasma concentrations and T1/2 after intravenous one-shot injection of FMOX in premature infants in group (0-3 (n = 14), 4-7 (n = 10), 8-28 (n = 13) days of birth). Mean C15's at doses of 10, 20 and 40 mg/kg in the different groups of infants were 24.0, 28.6, 21.7 and 54.0, 54.6, 55.5 and 98.2, 93.0, 106.0 micrograms/ml, and T1/2's were 4.10, 2.53, 2.57 and 4.28, 2.27, 3.02 and 4.66, 2.86, 2.09 hours, respectively. Mean Cmax values were clearly dose dependent, and mean T1/2 values tended to be longer in premature infants compared to neonates. (3) Urinary recovery rate of FMOX after intravenous injection in neonates and premature infants. Mean urinary recovery rates of FMOX in the first 6 hours after i.v. (one-shot) at doses of 10, 20 and 40 mg/kg to neonates and premature infants were 38.9-62.8% in the neonates and 30.7-61.5% in the premature infants. (4) Plasma concentrations and urinary recovery rates upon 1 hour drip infusion of 20 mg/kg in the neonate groups (or the premature infant groups) as follows: Mean C50 values were 31.0, 32.7 and 23.4 micrograms/ml, and T1/2 were 2.94, 3.68 and 2.25 hours, respectively. The recovery rates were 35.2-52.9% in the first 6 hours after administration. 2. Clinical studies The number of clinically evaluable cases in the FMOX treatment of premature infants was 199, in which the causative pathogens were identified in 71 cases (A group) and not identified in 128 cases (B group).(ABSTRACT TRUNCATED AT 400 WORDS)