Methods: The wet decantation process used to remove the surface carrier fines carried out nine time for both lactose and mannitol carriers. Addition of 2%, 4% and 8% lactose fines to decanted lactose. Additionally, mannitol fines of 4%, 8% and 16% added to decanted mannitol. In vitro deposition carried out for those treated carriers after mixing with salbutamol sulphate using a Next Generation Impactor (NGI). The treated carriers with fines characterized by scanning electron microscope, Brunauer Emmet and Teller specific surface area determination, differential scanning calorimetry, X-ray powder diffraction and water vapour sorption in comparison with the treated carrier without added fines.

Results: For decanted mannitol and decanted lactose carriers, there were significant increase in fine particle fraction (FPFs). This probably by reducing drug-carrier adhesion and allowing easy detachment of the drugs from the carrier surface. Although this addition of fines could not revert the FPFS to the original value of the untreated carriers, which may indicate that they were not equal to the original fines removed by wet decantation. Added carrier fines exhibit another shape, surface area and energetic charge than the inherent fines.

Conclusions: Addition of micronized carriers to decanted carriers found to increase significantly the dispersion of the drug and subsequently the FPF in the in vitro deposition test.