title: Effect of surface coating with magnesium stearate via mechanical dry powder coating approach on the aerosol performance of micronized drug powders from dry powder inhalers.
abstract: The objective of this study was to investigate the effect of particle surface coating with magnesium stearate on the aerosolization of dry powder inhaler formulations. Micronized salbutamol sulphate as a model drug was dry coated with magnesium stearate using a mechanofusion technique. The coating quality was characterized by X-ray photoelectron spectroscopy. Powder bulk and flow properties were assessed by bulk densities and shear cell measurements. The aerosol performance was studied by laser diffraction and supported by a twin-stage impinger. High degrees of coating coverage were achieved after mechanofusion, as measured by X-ray photoelectron spectroscopy. Concomitant significant increases occurred in powder bulk densities and in aerosol performance after coating. The apparent optimum performance corresponded with using 2% w/w magnesium stearate. In contrast, traditional blending resulted in no significant changes in either bulk or aerosolization behaviour compared to the untreated sample. It is believed that conventional low-shear blending provides insufficient energy levels to expose host micronized particle surfaces from agglomerates and to distribute guest coating material effectively for coating. A simple ultra-high-shear mechanical dry powder coating step was shown as highly effective in producing ultra-thin coatings on micronized powders and to substantially improve the powder aerosolization efficiency.
authors.affiliation: Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Melbourne, VIC, 3052, Australia. tonygoe1980@hotmail.com
authors.forename: Qi Tony
authors.initials: QT
authors.lastname: Zhou
authors.forename: Li
authors.initials: L
authors.lastname: Qu
authors.forename: Thomas
authors.initials: T
authors.lastname: Gengenbach
authors.forename: Ian
authors.initials: I
authors.lastname: Larson
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Stewart
authors.forename: David A V
authors.initials: DA
authors.lastname: Morton
mesh_terms: D000336:Aerosols; D058995:Dry Powder Inhalers; D010316:Particle Size; D056951:Photoelectron Spectroscopy; D011208:Powders; D013229:Stearic Acids / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D000336:Aerosols; D011208:Powders; D013229:Stearic Acids; C031183:stearic acid