Pharmacokinetics and sputum penetration of ciprofloxacin in patients with cystic fibrosis.

Levels of ciprofloxacin in serum and sputum were studied for eight patients with cystic fibrosis who were infected with Pseudomonas aeruginosa. Patients were studied in a steady state on a dosage of 500 mg every 8 h. Peak levels in serum ranged from 1.27 to 5.6 mg/liter (mean, 3.16 +/- 1.27), and absorption was rapid, the time to peak concentration ranging from 0.5 to 3.0 h (mean, 1.5 +/- 0.9). The antibiotic penetrated sputum well, achieving areas under the curve of approximately 46% of those obtained in serum.