Bronchial secretion levels of amikacin.

Abstract

Amikacin was given to 14 noninfected men as three consecutive intramuscular injections (7.5 mg/kg) at 12-h intervals. Serum and bronchial secretion specimens were obtained at various times during flexible fiberoptic bronchoscopy after the final dose. Serum and bronchial secretion concentrations obtained between 1.5 and 2.0 h after the final dose ranged from 17 to 40 mug/ml and 2.3 to 8.4 mug/ml with a mean of 23.7 +/- 2.9 and 5.23 +/- 1.5 mug/ml, +/-1 standard error of the mean, respectively. The highest bronchial secretion concentration in each subject correlated with the highest serum concentration (r = 0.83, P < 0.001), and all concurrent serum and bronchial secretion concentrations demonstrated a significant correlation (r = 0.82, P < 0.001). Clearance occurred at the same rate (half-life serum = 2.84 h; half-life of bronchial secretion = 2.60 h, P > 0.5). The mean bronchial secretion concentration of the 15 specimens obtained more than 7 h after the final dose was less than 1.0 mug/ml, with a range from 0.3 to 1.6 mug/ml. It is concluded that amikacin may achieve minimal inhibitory concentrations for many gram-negative bacteria in the bronchial secretions of noninfected patients 1 to 2 h after the final dose. However, levels fall below the reported minimal inhibitory concentrations against negative bacteria 6 to 7 h after the final dose. Furthermore, bronchial secretion levels may never reach the minimal inhibitory concentration against Pseudomonas aeruginosa.