title: Influence of particle size, air flow, and inhaler device on the dispersion of mannitol powders as aerosols.
abstract: OBJECTIVE
  To study the effect of particle size, air flow and inhaler type on the dispersion of spray dried mannitol powders into aerosols.
  
  
  METHODS
  Mannitol powders were prepared by spray drying. The solid state properties of the powders were determined by laser diffraction, X-ray powder diffraction, scanning electron microscopy, freeze fracture, Karl Fischer titration and gas pycnometry. The powders were dispersed using Rotahaler and Dinkihalerg, connected to a multistage liquid impinger at different air flows.
  
  
  RESULTS
  Three crystalline mannitol powders with primary particle size (MMD) 2.7, 5.0, 7.3 microm and a similar polydispersity were obtained. The particles were spherical with a density of 1.5 g/cm3 and a moisture content of 0.4 wt.%. At an air flow of 30 L/min all the powders were poorly dispersed by both inhalers. With the Rotahaler increasing the flow (60-120 L/min) increased the fine particle fraction (FPF) in the aerosols for the 2.7 microm powder, and decreased the FPF for the 7.3 microm powder; whereas the FPF for 5.0 microm powder was unaffected. With the Dinkihaler, all the powders were near complete dispersion at > or = 60 L/min.
  
  
  CONCLUSIONS
  The FPF in the mannitol powder aerosols was determined by an interplay of the particle size, air flow and inhaler design.
authors.affiliation: Department of Pharmacy, University of Sydney, NSW, Australia.
authors.forename: N Y
authors.initials: NY
authors.lastname: Chew
authors.forename: H K
authors.initials: HK
authors.lastname: Chan
mesh_terms: D000336:Aerosols; D055598:Chemical Phenomena; D002626:Chemistry, Pharmaceutical; D002627:Chemistry, Physical; D004234:Diuretics, Osmotic / Q000008:administration & dosage* / Q000737:chemistry; D008353:Mannitol / Q000008:administration & dosage* / Q000737:chemistry; D009330:Nebulizers and Vaporizers; D010316:Particle Size; D011208:Powders
chemical_list: D000336:Aerosols; D004234:Diuretics, Osmotic; D011208:Powders; D008353:Mannitol