Spray freeze drying: Emerging applications in drug delivery.

Spray freeze drying is relatively a recent drying technique involving heterogeneous set of steps which includes droplet formation, freezing, and sublimation. It has proven benefits over other drying methods in terms of producing products with improved structural integrity, superior quality, and better shelf stability. With such merits, spray freeze drying has found numerous applications in the field of drug delivery. Spray freeze drying yields particles of sizes and densities that show higher stability in the lungs, nasal mucosa, intestine, and skin, as compared to other drying technologies. These particles also possess the vital trait of sustained release and specificity through various delivery routes as compared to conventional drying techniques. This drives the market for commercialization of spray freeze dried drugs. The focus of this paper is on manufacturing approaches of spray freeze dried powders, with emphasis on its application in drug delivery systems. An overview of other applications of spray freeze drying is also presented.