Aerodynamic Particle Size Distribution -MDI
The aerodynamic particle size distribution (APSD) of the drug leaving an inhaler device can define the manner and location in which an aerosol deposits in the respiratory tract during inhalation. If the particle size is too large and the drug won’t reach the lungs, too small it will be exhaled, Aerodynamic particle size distribution is therefore a vital test for the efficacy of an inhaler.
This characteristic of the aerosol is often used in judging inhaler performance and is particularly relevant in the development of inhalation formulations during research, production, quality assurance and equivalency testing.
The results of characterisations using cascade impaction techniques are additionally used for the determination of fine particle fraction or fine particle dose which may be correlated to the dose or fraction of the drug that penetrates to the lung during inhalation by a patient (in vitro-in vivo correlation).