Modification in the pharmacokinetics of amikacin during development

The disposition kinetics of a single i.v. dose of amikacin was studied in 6 neonates (6-25 days old), 10 infants (4-18 months) and 8 young children (3-11 years). There was a progressive change in the distribution and elimination kinetics during development. The distribution coefficient of the antibiotic averaged of 0.429, 0.320 and 0.210 l/kg in the newborns, infants and young children, respectively and serum half-life (t1/2 beta) in these three groups averaged 2.812, 1.803 and 1.196 h, respectively. Significant differences in certain pharmacokinetic parameters were found between the values in paediatric patients and in adults receiving the same dose. A linear relationship was established between the distribution volume of the antibiotic and the weight of the patients, as defined by the following equation: Vdss (1) = 0.976 + 0.140 . TBW (kg); r = 0.954. The results suggest that a regimen of very frequent administrations should be employed in infants and young children in order to maintain a therapeutic level throughout treatment.