Increased oral bioavailability of ciprofloxacin in cystic fibrosis patients.

The altered pharmacokinetic properties of, e.g., aminoglycosides in cystic fibrosis patients have to be considered when pulmonary exacerbations are treated. Since reported data on ciprofloxacin, a fluorinated quinolone, are conflicting, we compared intravenous and oral administration in cystic fibrosis patients when treating them for mild symptoms of pulmonary infection. All of the patients were colonized with Pseudomonas species. Ciprofloxacin was administered orally (15 mg/kg of body weight) or intravenously (6 mg/kg) twice a day for at least 10 days during separate treatment periods. Five healthy volunteers received single intravenous and oral doses. Pharmacokinetic evaluations were performed at first dose and at steady state. The results showed that cystic fibrosis patients have increased oral bioavailability of ciprofloxacin (80% in cystic fibrosis patients versus 57% in volunteers) and increased total clearance (688 ml/min in CF patients versus 528 ml/min in volunteers). Our data indicate that the pharmacokinetic properties of ciprofloxacin are altered in cystic fibrosis patients with mild symptoms of pulmonary exacerbations and that the changes most probably are due to cystic fibrosis per se or to the impact of chronic infection.