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±1.1 μg/ml. The mean plasma concentration at 60 to 75 minutes after injection of the drug was 28.7 μg/ml with little interpatient variation (SD 3.5 μg/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.
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health