Abstract.To ensure consistency of clinical outcomes, orally inhaled therapies must exhibit consistent delivered dose and aerosol properties at the time of manufacturing, throughout storage, and during various patient-use conditions. Achieving consistency across these scenarios has presented a significant challenge, especially for combination products that contain more than one drug. This study characterized the delivered dose and aerosol properties of glycopyrrolate/formoterol fumarate metered dose inhaler (GFF MDI; Bevespi Aerosphere™). GFF MDI, a fixed-dose combination (FDC) of a long-acting muscarinic antagonist, glycopyrrolate (18 μg, equivalent to glycopyrronium 14.4 μg), and a long-acting β 2 -agonist, formoterol fumarate (9.6 μg; equivalent to formoterol fumarate dihydrate 10 μg), is formulated using innovative co-suspension delivery technology, which suspends micronized drug crystals with spray-dried phospholipid porous particles in hydrofluoroalkane propellant. In this study, delivered dose uniformity was assessed through the labeled number of doses, and aerosol properties, such as percent fine particle fraction (FPF) and mass median aerodynamic diameter, were determined by cascade impaction. GFF MDI achieved reproducible dose delivery and an FPF greater than 55%, whether formulated and delivered as a monocomponent or dual FDC. The performance of GFF MDI was maintained across various manufacturing batches, under extended storage, and with variations in flow rate. Furthermore, unlike a GFF drug crystal-only suspension, drug delivery remained consistent for GFF MDI when simulated patient-handling errors were applied, such as reduced shake energy and delays between shaking and actuation. These results demonstrate that cosuspension delivery technology overcomes well-known sources of variability in MDI drug delivery.KEY WORDS: dose consistency; co-suspension delivery technology; respiratory drug delivery; metered dose inhaler (MDI); chronic obstructive pulmonary disease (COPD).

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