The Advanced Integrated Respiratory (AIR) model: comparative analysis of salbutamol sulphate deposition from pMDI, DPI, and nebuliser versus the NGI

Purpose: In vitro respiratory models such as the Next Generation Impactor (NGI), remain the gold standard for aerodynamic particle size distribution (APSD) testing, however, they lack the anatomical complexity, limiting their ability to replicate in vivo deposition. To address this limitation, the Advanced Integrated Respiratory (AIR) model, a physiologically relevant benchtop system incorporating anatomically accurate silicone casts of the upper and lower airways, was used to assess deposition of salbutamol sulphate delivered via three clinically relevant platforms. Methods: Salbutamol sulphate was delivered using a pressurised metered-dose inhaler (pMDI), a dry powder inhaler (DPI), and a jet nebuliser. Deposition profiles obtained in the AIR model were benchmarked against the NGI. Results: Both systems showed consistent patterns for DPI and nebuliser aerosols, with highest deposition in the oropharyngeal and intrathoracic regions, respectively. In contrast, pMDI testing revealed important differences: the AIR model predicted markedly higher oropharyngeal retention and reduced intrathoracic delivery, aligning more closely with published in vivo scintigraphy studies than the NGI. Conclusion: These findings demonstrate that anatomically realistic models provide critical insights into deposition behaviour, particularly for propellant driven inhalers and underscore the value of integrating physiologically relevant platforms alongside conventional impactors in aerosol characterisation.