Abstract
Lower respiratory tract infections caused by Pseudomonas aeruginosa are a global concern. Patients with chronic lung diseases such as cystic fibrosis and non-cystic fibrosis bronchiectasis often do not receive adequate antibiotic delivery through conventional routes. P. aeruginosa employs several mechanisms, including biofilm formation and efflux pumps to limit the accumulation of bactericidal drug concentrations. Direct drug delivery to the lung epithelial lining fluid can increase antibiotic concentration and reduce treatment failure rates. This review discusses current research and developments in inhaled antibiotic formulations for treating P. aeruginosa infections. Recent studies on particle engineering for the dry powder inhalers of antibiotics emphasized three fundamental principles of development: micro, nano, and nano-in-microparticles. Carrier-free microparticles showed potential for high-dose delivery but suffered from poor aerosolization, which could be improved through a drug-drug combination. Amino acids in a co-spray-dried system improved powders' aerodynamics and reduced moisture sensitivity while incorporating the chitosan/poly(lactic-co-glycolic acid) (PLGA)-modified release of the drug. Nano-in-microsystems, embedding lipid carriers, showed improved antibiofilm activity and controlled release. We also highlight emerging biologics, including antibacterial proteins/peptides, vaccines, bacteriophages, and probiotics. Research on antibiotics and biologics for inhalation suggests excellent safety profiles and encouraging efficacy for some formulations, including antimicrobial peptides and bacteriophage formulations. Further research on novel molecules and synergistic biologic combinations, supported by comprehensive animal lung safety investigations, will be required in future developments.