Kinetic parameters of amikacin in cystic fibrosis children.

35 kinetic studies have been performed, in nine CF children three to 15 years old; six kinetic studies were performed in four non-CF children, one to 12 years old. The dosage was 5 to 12.5 mg/kg, i.v. during 0.5 to 1.0 h, three to four times per day. Amikacin concentrations were measured in the plasma of all children, and in the sputum of CF-patients, by fluorescent polarization (TDX Abbott). The pharmacokinetic parameters in the plasma did not differ significantly in both groups of patients. In CF children t1/2 = 0.94 h (SD = 0.25 h), Vd (area) = 0.257 l/kg (SD = 0.06 l/kg), total body clearance = 130.7 ml/min/1.73 m2 (SD = 32.4 ml/min/1.73 m2). In non-CF children t1/2 = 0.83 h (SD = 0.15 h), Vd (area) = 0.265 l/kg (SD = 0.04 l/kg) and clearance = 155 ml/min/1.73 m2 (SD = 17.4 ml/min/1.73 m2). The parameters were not affected by the dosage of amikacin. The peak plasma concentrations ranged from 19 to 43.8 mg/l. Amikacin peak level in the sputum of CF children never reached the average MIC (4 mg/l) of Pseudomonas aeruginosa strains isolated in these patients. Amikacin concentration in the sputum reached its highest value about 2 h after the completion of i.v. infusion and was directly related to the peak plasma concentration. According to these parameters, the best dosage regimen appeared to be 7.5 to 8 mg/kg or 225 to 240 mg/m2 administered intravenously in 1.0 h, three times per day.