Product/Process Characteristic	Description
Particle Size	Control of particle size is often important. For example both intravenous and pulmonary products have strict size requirements. Reproducibility of the size distribution is also a key factor in a successful product.
Particle Wall Thickness	The thickness of the particle wall will have a dramatic effect on powder bulk density and aerodynamic properties, allowing manipulation of powder handling properties.
Co-spray Drying	It is possible to spray dry mixtures of compounds. For example a solution containing both a protein and a stabilising sugar can be spray dried to enhance protein stability in the particles. Alternatively a solution of one compound containing a suspension of a second can be spray dried to achieve microencapsulation.
Post Spray Drying Modification	Spray dried particles may be chemically modified to change their functional characteristics or surface properties.