Summary
Due to environmental regulations the industry continues to reformulate existing drug products using the next generation propellants. The impact of this change is more prominent when considering suspension formulations as there are various factors that need to be considered as the physiochemical properties of the propellants change. This study provides suspension assessment of Salmeterol Xinafoate (SX), Glycopyrronium Bromide (GB) and Formoterol Fumarate Dihydrate (FFD) using static multiple light scattering technology. In particular, properties of migration rate, and dispersion have been assessed alongside comparison of SEM and in-situ propellant determined particle size with fresh and aged formulations.
The aged formulations for both propellants resulted in increased sedimentation rates across all APIs tested. The highest margin of increase for SX and FFD was observed in the HFA-134a formulations and the GB increased by the same amount for both propellants. The estimated particle size (hydrodynamic diameter) increased by approximately the same amount for all APIs in both propellants, where as the degree of dispersion was reduced for all APIs in HFA-134a and a mixture of effects was observed in the HFA-152a. The preliminary results indicate that reformulations of drug products with these APIs in HFA-152a will lead to equivalent or improved stability profiles.