Targeted Pulmonary Delivery of Ciprofloxacin via Chitosan Nanoparticles for the Treatment of Lower Respiratory Tract Infections

Introduction: Lower respiratory tract infections (LRTIs) remain a leading global health challenge, especially with the rise of multidrug-resistant (MDR) pathogens. Ciprofloxacin, although effective, has limitations when administered systemically. Chitosan, a biocompatible polymer, provides a promising platform for nanoparticle-based pulmonary delivery. Methods Nanoparticles were synthesized via ionic gelation using chitosan and sodium tripolyphosphate. twelve formulations varying in polymer and cross-linker concentrations were characterized for yield, entrapment efficiency, particle size, zeta potential, and in vitro drug release. Antimicrobial efficacy was tested against Staphylococcus aureus and Escherichia coli . Results Batch 7 consistently outperformed all others, showing the highest entrapment efficiency (89.4%), smallest particle size (185 nm), and maximum zeta potential (+ 41.1 mV). In vitro drug release of Batch 7 demonstrated sustained release up to 12 h with the highest cumulative release (85.3%), significantly exceeding other formulations. Antimicrobial testing confirmed superior inhibition zones (27 mm against S. aureus and 37 mm against E. coli ), validating its enhanced therapeutic activity. Discussion Among 12 formulations, Batch 7 emerged as the most optimized CIPRO-CSNP, combining superior physicochemical stability with strong antibacterial efficacy. Conclusion The findings highlight the potential of chitosan nanoparticles as an advanced pulmonary delivery system for combating resistant respiratory infections.