Epithelial Profiling of Antibiotic Controlled Release Respiratory Formulations

Release profiles of two ciprofloxacin hydrochloride formulations for the treatment of respiratory infection were evaluated using different in vitro methodologies and characterised for aerosol performance and toxicity. Spray-dried ciprofloxacin and ciprofloxacin spray-dried with polyvinyl alcohol as a controlled release (CR) agent at a 50:50 w/w ratio were formulated and physico-chemically characterised. Aerosol performances were assessed in vitro using a liquid impinger. Drug release was performed using a modified Franz cell and a validated air interface Calu-3-modified twin stage impinger (TSI). Ciprofloxacin toxicity was also established in vitro. Both formulations had a similar size distribution, while CR ciprofloxacin had superior aerosol performance and stability. The release profiles showed the CR formulation to have a higher transport rate compared to ciprofloxacin alone in the cell model. Contrary results were observed using the diffusion cell. Results suggest that the air interface cell model provides a more physiologically relevant model than the modified Franz cell. Toxicity analysis showed that the lung epithelial cells could tolerate a wide range of ciprofloxacin concentrations. This study establishes that the in vitro modified TSI air interface Calu-3 model is capable of evaluating the fate of inhaled powder formulations.