title: Adapting the Abbreviated Impactor Measurement (AIM) concept to make appropriate inhaler aerosol measurements to compare with clinical data: a scoping study with the "Alberta" idealized throat (AIT) inlet.
abstract: BACKGROUND
  The Abbreviated Impactor Measurement (AIM) concept simplifies determination of aerodynamic size metrics for inhaler quality control testing. A similar approach is needed to compare in vitro particle size distribution metrics with human respiratory tract (HRT) deposition.
  
  
  METHODS
  An abbreviated impactor based on the Andersen eight-stage cascade impactor (ACI) was developed having two size-fractionating stages with cut-points at 4.7 and 1.1 μm aerodynamic diameter at 28.3 L/min, to distinguish between coarse (CPM), fine (FPM), and extra-fine (EPM) mass fractions likely to deposit in the oropharynx, airways of the lungs, or be exhaled, respectively. In vitro data were determined for pressurized metered dose inhaler (pMDI)-delivered salbutamol (100 μg/actuation ex valve) with an "Alberta" idealized adult upper airway (throat) inlet (AIM-pHRT). Corresponding benchmark data for a full resolution Andersen eight-stage cascade impactor with "Alberta" idealized throat (ACI-AIT) and ACI-Ph.Eur./USP inlet were obtained with the same product.
  
  
  RESULTS
  Mass recoveries (μg/actuation; mean ± SD) were equivalent at 100.5 ± 0.7; 97.2 ± 4.9 and 101.5 ± 9.5 for the AIM-pHRT, ACI-AIT, and ACI-Ph.Eur./USP induction port, respectively [one-way analysis of variance (ANOVA), p=0.64]. Corresponding values of CPM were 59.2 ± 4.2; 58.4 ± 2.4, and 65.6 ± 5.8; the AIT captured larger particles more efficiently than the Ph.Eur./USP induction port, so that less large particle mass was apparent in the upper stages of the ACI-AIT (p ≤ 0.037). Equivalent values of FPM were similar regardless of inlet/abbreviation at 41.3 ± 4.2; 38.7 ± 3.0, and 35.9 ± 3.8 (p=0.054), and EPM measures (1.7 ± 0.3; 2.0 ± 0.5; 2.1 ± 0.3) were also comparable (p=0.32).
  
  
  CONCLUSIONS
  The AIT inlet significantly increased the capture of the coarse fraction compared with that collected by the Ph.Eur./USP induction port. Measures obtained using the AIM-pHRT apparatus were comparable with those obtained with the ACI-AIT.
authors.affiliation: Trudell Medical International, London, Canada. jmitchell@trudellmed.com
authors.forename: Jolyon
authors.initials: J
authors.lastname: Mitchell
authors.forename: Mark
authors.initials: M
authors.lastname: Copley
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Sizer
authors.forename: Theresa
authors.initials: T
authors.lastname: Russell
authors.forename: Derek
authors.initials: D
authors.lastname: Solomon
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000336:Aerosols; D000420:Albuterol / Q000008:administration & dosage*; D001993:Bronchodilator Agents / Q000008:administration & dosage; D004867:Equipment Design; D006801:Humans; D036501:Metered Dose Inhalers / Q000592:standards*; D008953:Models, Anatomic; D008954:Models, Biological; D010316:Particle Size; D011786:Quality Control; D012137:Respiratory System / Q000378:metabolism*; D013678:Technology, Pharmaceutical / Q000295:instrumentation
chemical_list: D000336:Aerosols; D001993:Bronchodilator Agents; D000420:Albuterol