Drug-coarse carrier interaction

The coarse carrier particles blended with micronized drug form an ordered or interactive mixture (Fig. 8.11) (Hersey 1975) stabilized by adhesive Lifshitz—van der Waals and electrostatic forces (Podczeck 1998 Hickey et al. 1994). The shear forces exerted in the airflow of a DPI device must be greater than the adhesive forces in order to provide sufficient deaggregation and dispersion of the drug particles. Unfortunately, however, this process is more or less incomplete and disperses only a proportion of the agglomerated drug particles depending on the inhalation airflow (Zanen et al. 1992). 

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