Clinical and laboratory studies with amikacin in newborns, infants, and children

Pharmacokinetics of amikacin in critically ill neonatal foals treated for presumed or confirmed sepsis

Fourteen foals less than four days of age were treated with the aminoglycoside, amikacin sulphate, and either penicillin or ampicillin for septicaemia, pneumonia, and/or failure of passive immunoglobulin transfer. Serum amikacin concentrations were determined at three times during an 8 or 12 h dosing interval. A 7.0 mg/kg bodyweight dose of amikacin every 8 h was appropriate. Prematurity did not influence mortality. All seven premature foals survived, whereas four of the seven full term foals died. Uraemia in three foals was caused by urinary bladder rupture; amikacin-induced nephrotoxicity was not recognised by clinical chemistries (elevations in serum creatinine or blood urea nitrogen concentrations) or post-mortem findings.

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.

Pharmacokinetics of amikacin in children with normal and impaired renal function

The pharmacokinetics of the antibiotic amikacin sulfate were studied in eight children with normal renal function and in ten children with varying degrees of renal impairment. All patients received a single i.v. dose of 7.5 mg/kg of the antibiotic. Amikacin follows a two-compartment open-kinetic model. The serum half-life, which in children with normal renal function has an average value of 1 hour, reached values of 14 hours in children with severe renal impairment. A lineal relationship is established between the beta constant and the creatinine clearance (Clcr) according to the equation beta = 0.001 + 0.005.Clcr, with r = 0,818. From thie equation, the dosage interval is modified to maintain the serum concentrations of the antibiotic within the therapeutic interval.

Amikacin in gram-negative paediatric infections

Amikacin was used in the treatment of various Gram-negative infections in sixty-six children ranging in age from two days to thirteen years. Over 72% of the infections treated were classified as severe and the remainder were moderate. Among infections in which the site of origin was the urinary or gastro-intestinal tract, amikacin achieved thirty-eight (95%) complete or partial cures in forty patients. In respiratory tract infections, amikacin completely or partially cured six (75%) out of eight patients. The remaining eighteen infections involved skin, soft tissue and other miscellaneous categories in which amikacin therapy resulted in seventeen (94%) complete or partial cures. Overall, amikacin achieved fifty-four complete cures and seven clinical or bacteriological cures in sixty-six patients, which represents an 82% complete cure rate and 10% partial cure rate for all the patients in the study.