Discriminating Ability of Abbreviated Impactor Measurement Approach (AIM) to Detect Changes in Mass Median Aerodynamic Diameter (MMAD) of an Albuterol/Salbutamol pMDI Aerosol

This article reports on results from a two-lab, multiple impactor experiment evaluating the abbreviated impactor measurement (AIM) concept, conducted by the Cascade Impaction Working Group of the International Pharmaceutical Aerosol Consortium on Regulation and Science (IPAC-RS). The goal of this experiment was to expand understanding of the performance of an AIM-type apparatus based on the Andersen eight-stage non-viable cascade impactor (ACI) for the assessment of inhalation aerosols and sprays, compared with the full-resolution version of that impactor described in the pharmacopeial compendia. The experiment was conducted at two centers with a representative commercially available pressurized metered dose inhaler (pMDI) containing albuterol (salbutamol) as active pharmaceutical ingredient (API). Metrics of interest were total mass (TM) emitted from the inhaler, impactor-sized mass (ISM), as well as the ratio of large particle mass (LPM) to small particle mass (SPM). ISM and the LPM/SPM ratio together comprise the efficient data analysis (EDA) metrics. The results of the comparison demonstrated that in this study, the AIM approach had adequate discrimination to detect changes in the mass median aerodynamic diameter (MMAD) of the ACI-sampled aerodynamic particle size distribution (APSD), and therefore could be employed for routine product quality control (QC). As with any test method considered for inclusion in a regulatory filing, the transition from an ACI (used in development) to an appropriate AIM/EDA methodology (used in QC) should be evaluated and supported by data on a product-by-product basis.