The current standard method for aerosol performance testing within the pharmaceutical industry is the Next Generation Impactor (NGI)(1, 2). During product development, there has been an increasing demand for higher throughput in analytical development and it has been observed that inhalation product performance testing with the NGI is a bottleneck in achieving rapid results. An alternative for the NGI is the Fast Screening Impactor (FSI), which shortens by about half the time the aerosol analysis by reducing amount of data generated; however, it is still time consuming and laborious. Another alternative for the two previous methods is the single aerosol mass spectrometry (SPAMS), which was initially developed for environmental and pollution studies(3) and is capable of detection of micrometer-sized target particles of low concentration(4). A new application for this technique is the analysis of dry powder formulations in pharmaceutical development.
For the present studies DPIs containing indacaterol maleate as the active pharmaceutical ingredient (API) with the excipient lactose in different dosage strength were chosen, in order to evaluate potential comparability between the two impaction methods (FSI, NGI) and SPAMS technique which can be further use as a fast screening method. The FPM and aerodynamic particle size distribution (APSD) profiles of different dosage strengths of API were compared with use of these three methods. By using of a simple mathematical calculation it was demonstrated that the SPAMS 3.0 could produce FPM data that can be consistently related to the results of independent NGI or FSI analyses. It was also shown that SPAMS results show internal consistency (good repeatability and reproducibility 5% RSD) and can be obtained in a shorter time of analysis (1-2 hours instead of 12-24 hours in case of impactors) compared to other techniques.