The distribution of ciprofloxacin and its metabolites in human plasma, pulmonary and bronchial tissues.

The disposition of ciprofloxacin and its pharmacologically active metabolites (sulfociprofloxacin, oxociprofloxacin, and desethylenciprofloxacin) in plasma, lung and bronchial tissues was studied in 24 patients undergoing a partial or total resection of the lung. The patients were divided into four groups, a control group and groups in which ciprofloxacin (200 mg) was given i.v. 1, 2 and 3 h before surgery. The concentrations of ciprofloxacin and its metabolites were determined by high performance liquid chromatography (HPLC). Ciprofloxacin concentrations in lung tissue were four times and in bronchial tissue twice those in plasma (p less than 0.01). The individual tissue concentrations of ciprofloxacin correlated with the individual plasma concentrations (r = 0.95 for lung; r = 0.94 for bronchi; p less than 0.001). Metabolite concentrations in both tissues and plasma were 10- to 100-fold lower than the concentrations of ciprofloxacin. These data suggest that the concentrations of the parent compound are essential for the therapeutic efficacy of ciprofloxacin.