Penetration of ofloxacin into bronchial secretions

The penetration of ofloxacin into bronchial secretions was evaluated in 16 patients after administration of a single oral dose of ofloxacin 400mg. Bronchial secretions were aspirated at bronchoscopy after 1 to 6 hours and serum was collected simultaneously. Ofloxacin concentrations were measured by a microbiological assay method. Considerable individual variations in serum and bronchial aspirate concentrations were recorded: bronchial aspirate concentrations varied between 1.1 mg/L and 4.5 mg/L but exceeded 1.5 mg/L in 14 of 16 patients between 1 and 6 hours. The ratio between simultaneous mean bronchial aspirate and serum concentrations ranged between 0.53 in the second hour and 0.92 in the fourth hour. It is likely that inhibitory activity will be sustained over at least 6 hours against most potential respiratory pathogens including Haemophilus influenzae, Branhamella catarrhalis, Gram-negative bacilli, Staphylococcus aureus, Legionella pneumophila and Mycoplasma pneumoniae. Streptococcus pneumoniae and Pseudomonas aeruginosa may have minimal inhibitory concentration (MIC) values lower than ofloxacin concentrations achieved in bronchial secretions, although some isolates are less sensitive. Clinical studies should establish the relevance of pharmacokinetic data to respiratory infections caused by organisms of borderline susceptibility.