Article ID: 2024.3034
The issues with pressurized metered-dose inhaler (pMDI) used for inhalation therapy in respiratory diseases include the misalignment of spray timing and inhalation, which can lead to medication adhering in the oral cavity and potential side effects. Spacers allow the aerosolized medication to linger in the chamber, enabling the patient to inhale at their own timing, thus eliminating the need for synchronization of spraying and inhalation. However, the adherence of medication to the spacer’s interior can reduce the amount of medication that can be inhaled. In this study, we used a system combining an inhalation simulator and an aerodynamic particle sizer (APS) to replicate patients inhalation patterns and measure the amount of aerosolized medication and particle size distribution, investigating the impact of spacers on aerosolized particles. By using a spacer, the inhalation speed and volume do not affect the process, allowing approximately 80% of the aerosolized medication to be inhaled under appropriate conditions. However, at slower inhalation speeds, the influence of the one-way valve was observed, indicating that it is necessary to select a spacer that matches the inhalation speed. Additionally, the amount of medication available for inhalation decreased with prolonged retention time after spraying, suggesting that patients should be instructed to begin inhalation promptly after spraying.
