Pharmacokinetics and therapeutic efficacy of amikacin given by intravenous drip infusion in cases of respiratory infection

In 8 patients with respiratory tract infection, the pharmacokinetics of amikacin, including its sputum level in one patient, were studied after a 60-minute intravenous infusion of 100 mg of amikacin. Also, therapeutic effects of amikacin combined with new cephems were evaluated in these patients. The concentrations of amikacin in serum and sputum were measured by fluorescence polarization immunoassay (FPIA) and bioassay, respectively. The serum concentration ranged from 6.10∼41.49μg/ml (mean±standard deviation [SD], 8.29±1.8) and was highest at the end of the infusion. After 30, 60, 120, 240 and 360 minutes, the serum concentration was 3.06∼4.66 (mean±SD, 5.24±1.2 μ/ml), 2.12∼5.41 (3.92±1.0), 1.02∼3.86 (2.87±0.9), 0.23∼2.11 (1.41±0.8) and 0.05∼1.46μg/ml (0.75±0.4), respectively. The half-life of amikacin was 2.20±0.79 h. The highest concentration of amikacin in sputum from one patient was 3.43μg/ml, which occurred 1 h after the end of the infusion. The maximum penetration rate of amikacin from serum to sputum was 37.7%. The therapeutic efficacy of amikacin combined with new cephems was excellent in 1 patient and good in 7 patients. No adverse reactions were observed during or after treatment. We conclude that the intravenous drip infusion of amikacin is useful and safe in the treatment of respiratory infections.