Abstract
The versatility of the pulmonary delivery route has encouraged recent research efforts to deliver a plethora of materials through the lungs, including pharmaceutical drugs, proteins, peptides, and DNA, for systemic circulations in the form of dry-powder aerosols. Therapeutic agents delivered through the pulmonary route are typically targeted to the lung alveolar region, which presents a large surface area for rapid absorptions into the systemic circulation. As a result of the rapid advances in nanotechnology, the use of inhaled nanoparticles as therapeutic carriers has become a subject of very active research. This review article covers the various methods to prepare micron-size dry-powder aerosols of nanoparticle aggregates intended for inhaled delivery by means of spray drying, spray-freeze-drying, and controlled precipitation. The selection of the preparation method, as well as the adjuvants and excipients used to convert nanoparticulate suspensions into the dry-powder form, depends on the physicochemical properties of the therapeutic agents and their encapsulation materials. An effective deposition of the therapeutic nanoparticles in the targeted lung region is achieved by creating nano-aggregate aerosols with appropriate aerodynamic diameters.
