Consistent aerodynamic performance and content uniformity of mometasone-magnesium stearate co-processed aerosols for...

Pressurized metered-dose inhalers (pMDIs) are a common technology for delivering respiratory medications, but the stability of suspended formulations remains a significant challenge. Physical instability can lead to dosing inaccuracies and reduced therapeutic effectiveness. While various stabilization strategies exist, these may entail high costs, complex processing and/or high excipient loading. This study evaluated the impact of magnesium stearate (MgSt) incorporation on delivered dose content uniformity and aerodynamic performance of mometasone-based pMDI suspensions. Different processing strategies were investigated: physical blending of MgSt with raw mometasone, physical blending of MgSt with spray-dried mometasone and co-spray drying of mometasone and MgSt. In all formulations, the mometasone:MgSt ratio was maintained at 99:1. Spray drying preserved the crystalline structure of mometasone and yielded small microparticles, similar in size and with a relatively narrow particle size distribution to the raw material. Raw mometasone, either alone or physically mixed with MgSt, failed to achieve acceptable delivered dose uniformity. In contrast, pure spray-dried mometasone, either alone or physically mixed with MgSt, showed improved results. The co-processed formulation demonstrated the highest emitted dose consistency, with delivered doses ranging between 90 and 100% of the nominal dose, thus remaining within typical regulatory limits. Additionally, co-processed formulations demonstrated adequate aerodynamic behavior, achieving an emitted fraction of 95% and a fine particle fraction of around 30%, comparable to commercially available pMDIs. Aerodynamic performance as well as dose emitted consistency was not importantly affected after six-months-storage. Overall, these findings confirm that spray-drying co-processing with MgSt effectively improves mometasone suspension performance.