Effect of Interval Between Actuations of Albuterol Hydrofluoroalkane Pressurized Metered-Dose Inhalers on Their Aerosol Characteristics

Decreasing the interval between actuations from 60 to 30 and 15 s does not seem to affect the aerosol characteristics of ProAir and Ventolin. Although some changes were noticed for Proventil, the pMDI outperformed Ventolin that had the lowest fine-particle mass. The use of a valved holding chamber increased fine-particle mass, but introducing a 10-s delay between actuation and inhalation significantly reduced fine-particle mass.