Evaluation of various techniques for production of inhalable dry powders for pulmonary delivery of peptide and protein

Therapeutic protein and peptides have gained dramatic interest in the recent years for the chronic diseases, although there are specific limitations in the delivery route. Due to degradability and low absorption, they are usually administered through parenteral route. However, due to low patient compliance and side effects studies have moved towards less invasive drug delivery systems. Pulmonary drug administration is among the promising alternatives since studies proved acceptable bioavailability and stability of the such protein-based medicines. Moreover, there are different pulmonary administered drugs such as Pulmozyme®, Exubera® and Afrezza® which are FDA approved. The critical issue is the stabilization of proteins through developing desirable dry powder formulations. So that different drying techniques and stabilizing excipients are evaluated. Various drying methods such as spray drying, freeze drying and supercritical fluid are used to achieve inhaled protein and peptide powders with desirable properties. The current paper discusses the main drying methods for inhalation delivery of proteins and peptides. Additionally, it categorizes existing inhaled peptides and proteins according to preparation techniques and formulations. Recent advances in drying methods such as supercritical fluid assisted atomization introduced by hydrodynamic cavitation mixer (SAA-HCM) technique is further discussed.