title: Introduction of the electrical next generation impactor (eNGI) and investigation of its capabilities for the study of pressurized metered dose inhalers.
abstract: OBJECTIVE
  To introduce the design of the electrical next generation impactor (eNGI), and validate its proposed function as a method of electrostatic characterization for pressurized metered dose inhaler (pMDI) formulations.
  
  
  METHODS
  Flixotide (fluticasone propionate), ventolin (salbutamol sulphate), and qvar (beclomethasone dipropionate) were used as model pMDIs in this study. At an airflow rate of 30 l/min, five individual actuations of each pMDI were introduced into the electrical low-pressure impactor (ELPI), Next Generation Impactor (NGI), and the eNGI. Charge profiles for each actuation were measured by the ELPI and eNGI, while mass profiles were recorded by the all three impactors.
  
  
  RESULTS
  The difference in estimated mass median aerodynamic diameters and geometric standard deviations for all pMDIs using the NGI and eNGI were not found to be statistically significant (p<0.05). The mean charge profiles from the ELPI and eNGI overlap well between 0.54 and 6.61 microm (flixotide and ventolin), and between 0.615 and 11.72 microm (qvar), where the majority of the impacted doses were collected.
  
  
  CONCLUSIONS
  For the analysis of pMDIs, the eNGI is comparable to the NGI in measuring particle size distribution, while still being comparable to the ELPI in measuring charge distribution.
authors.affiliation: Advanced Drug Delivery Group, Faculty of Pharmacy (A15), University of Sydney, Sydney, New South Wales, 2006, Australia.
authors.forename: Susan
authors.initials: S
authors.lastname: Hoe
authors.forename: Paul M
authors.initials: PM
authors.lastname: Young
authors.forename: Hak-Kim
authors.initials: HK
authors.lastname: Chan
authors.forename: Daniela
authors.initials: D
authors.lastname: Traini
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols; D000420:Albuterol / Q000737:chemistry; D000730:Androstadienes / Q000737:chemistry; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage / Q000737:chemistry*; D001507:Beclomethasone / Q000737:chemistry; D004867:Equipment Design; D000068298:Fluticasone; D036501:Metered Dose Inhalers; D010316:Particle Size; D011312:Pressure; D015203:Reproducibility of Results; D055672:Static Electricity; D013678:Technology, Pharmaceutical / Q000295:instrumentation*
chemical_list: D000336:Aerosols; D000730:Androstadienes; D018927:Anti-Asthmatic Agents; D000068298:Fluticasone; D001507:Beclomethasone; D000420:Albuterol