Ciprofloxacin concentrations in lung tissue following a single 400 mg intravenous dose

Intravenous ciprofloxacin is frequently prescribed for the treatment of infections due to nosocomially acquired gram-negative organisms, including those originating in the respiratory tract. In this study, the concentrations of ciprofloxacin in serum and lung tissue were determined by HPLC in patients undergoing lung surgery. A total of 22 patients scheduled for lung surgery received a single 400 mg i.v. dose of ciprofloxacin administered as a 1 h infusion. A specimen of healthy lung tissue was obtained from resected lung from 18 of the patients for analysis of ciprofloxacin concentration during the following time intervals after infusion (one sample/patient): 0-2, 2-4, 4-8 and 8-12 h. Corresponding mean serum and tissue concentrations were 2.37 mg/L and 3.84 mg/kg (0-2 h), 1.18 mg/L and 1.92 mg/kg (2-4 h), 0.69 mg/L and 1.77 mg/kg (4-8 h), and 0.13 mg/L and 0.67 mg/kg (8-12 h). Ciprofloxacin distributed rapidly to lung tissue, as seen by the high concentrations in the lung tissue as early as 2 h after infusion. Concentrations in lung tissue were generally higher than those in serum (tissue:serum ratios ranged from 1.7 to 7.1). The mean tissue concentrations found in this study remained above the MIC for most susceptible organisms.