Recent advances in dry powder inhalation formulations prepared by co-spray drying technology: a comprehensive review

Co-spray drying technology represents an increasingly important approach in preparing dry powder inhalation (DPI) formulations. Compared to conventional spray drying, co-spray drying typically yields particles characterized by improved aerosol performance and enhanced physicochemical stability. Despite its widespread application over the past decades, this technology remains under-represented in literature reviews. Therefore, we proposed to bridge the gap between co-spray drying and DPIs. In this review, we first elucidate the mechanism underlying co-spray drying as well as the critical process parameters impacting its effectiveness. We subsequently compile a list of commonly employed excipients utilized during the co-spray drying process. Thereafter, we summarize analytical techniques pivotal in evaluating DPIs performance, such as aerodynamic performance, solid state characterization, alongside relevant analyses pertaining to different drug molecules. Furthermore, this review provides a comprehensive overview of diverse applications of co-spray drying across various drug modalities, including small molecules, peptides, proteins, and gene therapy. More importantly, this technique has demonstrated significant potential in delivering biologics locally to treat pulmonary diseases. Additionally, we explore the growing significance and feasibility of integrating Artificial Intelligence and machine learning in developing DPIs prepared by co-spray drying, thereby substantially facilitating the formulation development of co-spray dried DPIs.