Descriptors of irregular particle morphology and powder properties

The description of irregular particle morphology and powder properties may offer unique insights into the performance of materials intended for use in dry powder inhalers. A number of mathematically similar approaches have been used to study these phenomena, all based on evaluating data in terms of irregular oscillations around a mean value. The specific methods described are Fourier, fractal and chaos analysis, stochastic and percolation models. Data describing the morphology of disodium cromoglycate particles, the behaviour of lactose and sodium chloride powders and dispersion of Intal(R) (disodium cromoglycate/lactose blend) utilizing a Spinhaler(R) is presented to demonstrate the application of these approaches to dry powder inhaler systems. It is envisaged that these techniques may be used to characterize powders with a view to guiding formulation and that ultimately this may lead to a greater understanding of the nature and magnitude of performance variables. (C) 1997 Elsevier Science B.V.