The purpose of this study was to formulate a dry powder for inhalation containing a combination treatment for eradication of Pseudomonas aeruginosa bacterial biofilms. Dry powders containing an antibiotic (ciprofloxacin hydrochloride, CH) and nutrient dispersion compound (glutamic acid, GA) at a ratio determined to eliminate the biofilms were generated by spray drying. Leucine was added to the spray dried formulation to aid powder flowability. A central composite design of experiments was performed to determine the effects of solution and processing parameters on powder yield and aerodynamic properties. Combinations of CH and GA eradicated bacterial biofilms at lower antibiotic concentrations compared to CH alone. Spray dried powders were produced with yields up to 43% and mass mean aerodynamic diameters (MMAD) in the respirable range. Powder yield was primarily affected by variables that determine cyclone efficiency, i.e. atomizer and solution flow rates and solution concentration; while MMAD was mainly determined by solution concentration. Fine particle fractions (FPF)<4.46μm and <2.82μm of the powders ranged from 56 to 70% and 35 to 46%, respectively. This study demonstrates that dry powder aerosols containing high concentrations of a combination treatment effective against P. aeruginosa biofilms could be developed with high yield, aerodynamic properties appropriate for inhalation, and no loss of potency.
Keywords: Central composite design; Ciprofloxacin; Fine particle fraction; Mass median aerodynamic diameter; Pseudomonas aeruginosa; Spray drying.
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