Spray drying is used to produce engineered, inhalable dry powders and is a critical tool for new drug developers. It enables production of powders with a tightly controlled range of particle sizes and solid-state properties. Formulators have control over the crystalline and amorphous character and radial distribution of components and particle morphology. This comes from understanding the impact of each material’s physicochemical properties and the kinetics of droplet drying.
Many key process inputs and variables must be considered when designing an inhaled formulation and the associated spray-drying process. Atomization, solution composition, solvent and excipient selection, and particle collection are some factors that have the largest influence on material properties. Since the particle size of the drug product is critical for inhaled therapies, optimizing these variables to manufacture particles of the targeted size, with appropriate aerodynamic properties, is a primary objective of respiratory programs. This article discusses these considerations and expands them into current applications.