[Pharmacokinetic and clinical investigation of amoxicillin administered intravenously in the newborn ].

Neonatal antibiotherapy involves special requirements which justify carrying out a clinical and pharmacokinetic investigation of amoxicillin. Our study concerns 34 newborn babies prone to infection divided in 3 groups: 26 newborns at gestational age; 6 hypotrophic and slightly premature newborns (age: 34 at 37 weeks); 1 highly premature baby (28 weeks, 0,9 kg). After direct IV drip of 33 mg/kg, 4 plasma concentrations analyses at time 0,5 1, 3, 8 hours, as well as an analysis of the urine from 0 to 8 hours are carried out by method of disk diffusion in nutrient agar. The main pharmacokinetics parameters are the following: half-live elimination time: 5.l4 +/- 3.43 hours; volume of distribution: 1.38 +/- 1.13 l/kg; total clearance: 0.211 +/- 0.277 l/kg/h. There is no correlation between birth weight and the parameters studied. However in the case of hypotrophic baby the volume of distribution is higher than for the child born after full gestation and may be partly correlated with the weight at birth. The same holds for clearance (correlation index of 0.66 and 0.59 respectively). The extreme variability of the pharmacokinetics parameters for newborn babies leads the authors to recommend a minimum dose of 150 mg/kg per day spread over 3 or 4 injections per day.