Introduction To assure consistency of clinical outcomes, orally inhaled products must have consistent in vitro delivered dose and aerosol properties. Achieving this consistency has been challenging with MDIs, particularly those that combine multiple drugs. Co-Suspension™ delivery technology has been developed for in vitro drug-drug interaction-free delivery of multiple drugs from fixed-dose MDI combinations. This versatile technology suspends the micronised drugs with spray-dried phospholipid porous particles in hydrofluoroalkane propellant. The objective of this study was to determine whether BGF MDI, the triple Co-Suspension delivery technology formulation of BD/GP/FF, displays in vitro drug delivery comparable to its constituent single and dual drug formulations.

Methods Single, dual and triple therapy MDIs of BD, GP and FF were prepared by suspending each drug’s microcrystals with phospholipid porous particles in HFA propellant. In vitro drug delivery was assessed by comparing delivered dose uniformity and aerodynamic particle size distribution.

Results BD, GP and FF formed stable suspensions in the presence of phospholipid porous particles, despite differences in drug physicochemical properties and doses. A consistent and comparable delivered dose and aerodynamic particle size distribution was observed whether emitted from a single, dual or triple therapy MDI.

Conclusion The single, dual and triple drug MDI formulations demonstrated comparable aerosol characteristics which should enable patients to transition across the continuum of these MDI therapies without in vitro drug-drug interaction impacting drug delivery and clinical outcomes.