[Pharmacokinetic and clinical studies on cefmenoxime in neonates and premature infants].

Cefmenoxime (CMX) was administered by intravenous bolus injection to a total of 23 neonates and premature babies with aged 1 to 26 days at a dose of 10 or 20 mg/kg and their plasma and urine concentrations and urinary recovery rates were determined up to 6 hours after administration. In addition, for the treatment of bacterial infections, diagnosed or suspected, or for the prophylaxis of bacterial infections, the drug was administered to a total of 27 neonates, premature babies and infants, with ages of 0 day to 3 months. It was possible to evaluate therapeutic efficacy and prophylactic efficacy in 15 cases and 7 cases, respectively. In these cases, side effects and bacteriological effects and, in some of them, changes in laboratory test values were also investigated. The obtained results are summarized below. 1. At a dose level of 10 mg/kg (n = 7), peak plasma concentrations at 5 minutes after administration, were 42.6 microns/ml in neonates with ages of 15 to 21 days and 45.9 microns/ml in those with ages of 22 to 28 days in a group of less than 2,500 g b.w. (birth weight), and 36.9 microns/ml in neonates with ages of 4-7 days and 38.9 microns/ml in those of 8-14 days in the other group of greater than of equal to 2,500 g b.w., indicating no large differences among the 4 subgroups (each of the above concentration values is either the value for an individual when only one neonates was involved or a mean value when 2 or more neonates were involved. The same applies hereinafter). Though 1 exceptional case showed a biphasic change, its cause is unknown. Half-lives in the above-mentioned 4 subgroups were 1.5, 1.6, 2.4 and 1.9 hours, respectively. The half-life of 2.4 hours in 1 patient with an age of 5 days of the greater than or equal to 2,500 g b.w. group was longer than in any of the other 3 subgroups. 2. At 20 mg/kg (n = 16) dosage level, mean peak plasma concentrations were 63.8 microns/ml in the infants of 0-3 days, 68.1 microns/ml in those of 8-14 days and 59.4 microns/ml in those of 15-21 days in the group of less than 2,500 g b.w., and 109.9 microns/ml in the neonates aged 8-14 days and 79.7 microns/ml in those of 15-21 days in the group greater than or equal to 2,500 g b.w.(ABSTRACT TRUNCATED AT 400 WORDS)