Seady-state plasma and intrapulmonary concentrations of levofloxacin and ciprofloxacin in healthy adult subjects

Study objective: To determine the steady-state plasma, epithelial Lining fluid (ELF), and alveolar macrophage (AM) concentrations of levofloxacin and ciprofloxacin. Design: Multiple-dose, open-label, randomized pharmacokinetic study. Participants: Thirty-six healthy, nonsmoking adult subjects were randomized either to oral levofloxacin, 500 or 750 mg once daily for five doses, or ciprofloxacin, 500 mg q12h for nine doses, Interventions: Venipuncture, bronchoscopy, and BAL were performed in each subject at 4 h, 12 h, or 24 h after the last administered dose of antibiotic. Measurement and results: Mean plasma concentrations of levofloxacin and ciprofloxacin were similar to those previously reported. For once-daily dosing of levofloxacin, 500 mg, the mean (+/- SD) steady-state concentrations at 4 h, 12 h, and 24 h in ELF were 9.9 +/- 2.7 mug/mL, 6.5 +/- 2.5 mug/mL, and 0.7 +/- 0.4 mug/mL, respectively, AM concentrations were 97.9 +/- 80.0 mug/mL, 36.7 +/- 23.4 mug/mL, and 13.8 +/- 16.0 mug/mL, respectively. For levofloxacin, 750 mg, the mean steady-state concentrations in ELF were 22.1 +/- 14.9 mug/mL, 9.2 +/- 5.3 mug/mL, and 1.5 +/- 0.8 mug/mL, respectively; AM concentrations were 105.1 +/- 65.5 mug/mL, 36.2 +/- 26.1 mug/mL, and 15.1 +/- 2.0 mug/mL;, respectively. The concentrations of ciprofloxacin at 4 h and 12 h in ELF were 1.9 +/- 0.9 mug/mL and 0.4 +/- 0.1 mug/mL, respectively; AM concentrations were 34.9 +/- 23.2 mug/mL, and 6.8 +/- 5.9 mug/mL, respectively. The differences in the ELF concentrations of the two levofloxacin groups vs those of the ciprofloxacin group were significant (p < 0.05) at each sampling time. Conclusions: Levofloxacin was more extensively distributed into intrapulmonary compartments than ciprofloxacin and achieved significantly higher steady-state concentrations in plasma and ELF during the 24 h after drug administration.