Study to Evaluate the Safety and Pharmacokinetics of Inhaled Ciprofloxacin in Patients With Moderate to Severe Chronic Obstructive Pulmonary Disease (COPD)

32.5 mg ciprofloxacin betaine corresponding to 50 mg Ciprofloxacin PulmoSphere inhalation powder will be given as an initial single-dose inhalation (day 0).During the multiple-dose phase (day 2 to day 11), the same dose will be given twice daily, with a concluding single dose (on day 12)

48,75 mg ciprofloxacin betaine corresponding to 75 mg Ciprofloxacin PulmoSphere inhalation powder will be given as an initial single-dose inhalation (day 0).During the multiple-dose phase (day 2 to day 11), the same dose will be given twice daily, with a concluding single dose (on day 12)

Placebo inhalation powder will be given as an initial single-dose inhalation (day 0).During the multiple-dose phase (day 2 to day 11), placebo will be given twice daily, with a concluding single dose (on day 12)