Characterization of novel spray-dried polymeric particles for controlled pulmonary drug delivery

Numerous studies have addressed the controlled pulmonary drug delivery properties of colloidal particles. However, only scant information on the potential of spray-drying for submicron particle preparation is available. By exploiting the advantages of spray-drying, the characteristics of submicron particles can be optimized to meet the requirements necessary for lung application. Submicron particles were prepared from organic poly(d,l-lactide-co-glycolide) (PLGA) solutions, and composite particles were spray-dried from aqueous PLGA nanosuspensions. The feed concentration, as well as the spray-mesh diameter influenced the resulting particle sizes. Nanoparticles were virtually unaffected after spray-drying. The aerodynamic characteristics of both particle species revealed aerosol particle sizes suitable for deposition in the deep lungs (≤4μm). While the entrapped drug was released within ~90min from the composite particles, extensive drug retardation (~480min) was observed for PLGA particles spray-dried from organic solution. These results suggest that nanospray-drying is a convenient method to prepare submicron, controlled drug delivery vehicles useful for pulmonary application potentially allowing access to alveolar tissue.