Medical aerosols: Techniques for particle size evaluation

Methods for the in-vitro measurement of the particle size distribution of aerosols from medical aerosol delivery systems, including pressurized metered-dose inhalers (pMDIs), dry powder inhalers (DPIs) and nebulizers, are reviewed with emphasis on their applicability both for compendial testing and for simulation of patient use. The importance of real-time measurement techniques, particularly for routine quality control testing, is also discussed, despite the current lack of a means to obtain absolute measurements of drug mass with these systems.