The article describes a series of in vitro test methods that can be used to estimate the total and regional lung doses. The focus of the discussion is on research and development, with the view that the ability to estimate total and regional lung deposition is essential in the design of efficient orally inhaled products. In this context, a new filter-based apparatus that mimics both the aerodynamic particle size and flow rate dependencies of regional lung deposition will be described.
The filter-based apparatus is intended to alleviate the complexity and resource burden of cascade impactor-based in vitro/in silico methods used to estimate regional lung deposition. For both DPIs and pMDIs, the approach has been shown to provide direct measurement of regional deposition in good agreement with in vitro/in silico estimates made using an Alberta Idealized Throat (AIT), a Next Generation Impactor (NGI), and the Aerosol Research Laboratory of Alberta’s in-house regional deposition modeling software. The approach, therefore, has the potential to expedite research and development of novel orally inhaled products that aim to target the tracheobronchial or alveolar regions of the lungs, as well as comparisons of equivalence between innovator products and generics.