Effects of mechanical impaction on aerosol performance of particles with different surface roughness

The effect of mechanical impaction on the aerosol performance of pharmaceutical powders comprising smooth and rough-surfaced spherical particles was investigated. Bovine serum albumin (BSA) was chosen as a model drug and powders prepared using spray drying. Surface roughness and adhesion force properties of BSA were measured by atomic force microscopy. The aerosol performance of the powders was assessed by impaction using a customised throat model built with specific mitre joints (0, 15, 45 and 90°), coupled with a liquid impinger through a laser diffractometer. Results showed enhanced aerosol performance of BSA by mechanical impaction, with the effect increasing with the impaction angle and being more pronounced with corrugated BSA. This is attributed to the lower cohesion force between the corrugated particles, enabling them to de-agglomerate more readily on impaction. In conclusion, impaction causes significantly better deagglomeration in corrugated particles than smooth particles. A combination of mechanical impaction and rough surface will help maximise the aerosol performance of powders for inhalation drug delivery.

The use of mechanical impaction and corrugated particles was found to be effective in improving the amount of fine particles generated. Corrugated BSA exhibits the maximal de-agglomeration efficiency at 90° impaction compared to smooth BSA due to its reduced adhesive force and hence more readily dispersed into fine fragments upon impaction.Figure optionsDownload as PowerPoint slideHighlights
► Smooth and corrugated bovine serum albumin (BSA) were produced by spray drying.
► Lower cohesion force between corrugated particles than smooth particles.
► Mechanical impaction affects the aerosol performance (i.e. Fine Particle Fraction).
► Corrugated BSA produces higher FPF than smooth BSA at all impaction angles.
► Mechanical impaction together with rough surface maximise powder deagglomeration.