The pharmacokinetics of amikacin in children.

The pharmacokinetic variables of amikacin were measured in 20 children and adolescents, 
four to 16 years of age. The mean plasma clearance of 
amikacin was 120 ml/minute/1.73 m2. The major route of elimination was 
renal (82%). Simultaneously measured inulin clearance showed that a majority (64%) 
of the drug filtered by the kidneys was excreted in the 
urine. The mean volume of distribution of amikacin was 32% of 
body weight; half-life during the final (pseudoequilibrium) phase averaged 1.6 hours. 
No significant accumulation of the drug was seen when four doses 
were given intravenously at 420 mg/m2 every 8 hours; the plasma 
concentration just before injection of the fourth dose averaged 2.4 plus 
or minus 1.1 microgram/ml. The mean plasma concentration at 60 to 
75 minutes after injection of the drug was 28.7 microg/ml with 
little interpatient variation (SD 3.5 microg/ml). When the dose was expressed 
in terms of milligrams per kilogram, it was found that children 
often needed 50 to 100% more of the drug, compared to 
adults, to achieve equivalent plasma concentrations; this larger requirement was primarily 
due to a higher clearance of amikacin in proportion to body 
weight. Dosages based on surface area, however, resulted in uniform requirements 
and predictable plasma concentrations in all patients studied. 