title: In vitro tests for aerosol deposition. III: effect of inhaler insertion angle on aerosol deposition.
abstract: BACKGROUND
  Inhaler orientation with respect to a patient's mouth may be an important variable determining the efficiency of aerosol lung delivery. The effect of insertion angle on regional deposition was evaluated for a series of inhalers using concurrent in vitro and computational fluid dynamics (CFD) analysis.
  
  
  METHODS
  Geometrically realistic physical mouth-throat (MT) and upper tracheobronchial (TB) models were constructed to connect different inhalers at a series of insertion angles relative to the horizontal plane of the model. These models were used to assess albuterol sulfate deposition from the Novolizer(®) dry powder inhaler (DPI), Proventil(®) HFA pressurized metered dose inhaler (MDI), and Respimat(®) Soft Mist™ Inhaler (SMI) following the actuation of a single dose. Drug deposition from Novolizer DPI was studied for Salbulin(®) and an experimental "drug only" formulation. Albuterol sulfate was recovered and quantified from the device and the MT and TB regions.
  
  
  RESULTS
  Significant differences in MT and total lung dose (TLD) of albuterol sulfate deposition were not observed for Salbulin Novolizer DPI and Respimat SMI inserted at different angles. In contrast, drug-only Novolizer DPI and Proventil HFA MDI showed a significant difference in MT and TLD deposition using different insertion angles. For drug-only Novolizer DPI and Proventil HFA MDI, the lowest and the highest MT depositions were observed at +10° and -20°, respectively; for Respimat SMI and Salbulin Novolizer DPI, these angles were -10° and +10°, and +20° and -20°, respectively. CFD simulations were in agreement with the experimental results and illustrated shifts in local particle deposition associated with changes in insertion angle.
  
  
  CONCLUSIONS
  The effect of inhaler orientation at the inhaler-mouth interface on MT aerosol deposition appeared to be dependent on velocity, aerosol size, and formulation. These findings not only demonstrate the need for patient education on correct inhaler orientation, but provide important new methods for those designing new inhalers.
authors.affiliation: Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: Renish R
authors.initials: RR
authors.lastname: Delvadia
authors.forename: P Worth
authors.initials: PW
authors.lastname: Longest
authors.forename: Michael
authors.initials: M
authors.lastname: Hindle
authors.forename: Peter R
authors.initials: PR
authors.lastname: Byron
mesh_terms: D000336:Aerosols; D000420:Albuterol / Q000008:administration & dosage / Q000493:pharmacokinetics*; D016503:Drug Delivery Systems; D058995:Dry Powder Inhalers; D004867:Equipment Design; D006801:Humans; D057446:Hydrodynamics; D008168:Lung / Q000378:metabolism*; D036501:Metered Dose Inhalers; D008953:Models, Anatomic; D009330:Nebulizers and Vaporizers; D010316:Particle Size; D014018:Tissue Distribution
chemical_list: D000336:Aerosols; D000420:Albuterol