A Study of the Effect of Jet Milling Process with or without Pre-treatment on Aerosolisation Characteristics of FITC-Dextran Particles

Moawia M. Al-Tabakha, Adi I. Arida


In vitro aerosolisation studies from a Spinhaler into the Andersen Cascade Impactor (ACI) of fluorescein isothiocyanate (FITC) -Dextran M. Wt. 4,400 (model drug) produced by different techniques were carried out. Three techniques, namely; micronisation, freeze-drying followed by micronisation and spray-drying followed by micronisation, were used to produce FITC-Dextran samples of similar particle sizes (Volume Median Diameter (VMD) =5.7μm) which, yet, differ in their surface characteristic. The measured Specific Surface Areas (SSAs) of FITC-Dextran were different, which indicated different surface characteristics. Wadell’s shape factor was calculated to provide measurement for the particles’ shape. Device retention after aerosolisation was similar for the three formulations as it was high, which is a characteristic of Spinhaler. However, the dispersion of each of the aerosolised blends were distinctly different from the others, as it was noticed that the micronised FITC-Dextran performed better than the remaining samples. The results were explained on the basis that porous particles of the micronised FITC-Dextran, as indicated by the SSA and the use of electron microscope, are light in weight, and therefore would have lower inertia; allowing them by this to remain longer in the airstream before impaction.


FITC-Dextran; Dry powders for inhalation; Surface characteristics; Wadell’s factor; Spinhaler; Andersen Cascade Impactor

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