title: The influence of flow rate on the aerosol deposition profile and electrostatic charge of single and combination metered dose inhalers.
abstract: OBJECTIVE
  The capability of the electrostatic next generation impactor (eNGI) has been investigated as a tool capable of measuring the electrostatic charge of single (Flixotide; containing fluticasone propionate (FP)) and combination (Seretide; FP and salmeterol xinafoate (SX)) pressurised metered dose inhalers (pMDIs) at different flow rates.
  
  
  METHODS
  Aerosol mass distributions were investigated at 30, 60 and 90 l.min(-1) and simultaneous charge measurements recorded.
  
  
  RESULTS
  Analysis of the mass distribution data indicated a flow dependent relationship, where the aerosol performance (aerodynamic diameter <5 mum) of FP significantly increased between 30 l.min(-1) and 60 l.min(-1) for both formulations. No significant increase in SX was observed for Seretide with increased flow rate. Analysis of the charge distribution indicated both formulations to primarily charge negatively with a concurrent increase in charge with increased flow rate. Interestingly, the charge-tomass ratio remained relatively constant between 30 l.min(-1) and 60 l.min(-1) and increased at 90 l.min(-1), indicating that charging was majorly influenced at the highest flow rate.
  
  
  CONCLUSIONS
  This study has shown how the eNGI could be used as a simple Pharmacopeia based methodology for the evaluation of mass and charge profiles of single and combination pMDIs at a series of flow rates.
authors.affiliation: Advanced Drug Delivery Group, Faculty of Pharmacy, University of Sydney, Sydney, NSW, 2006, Australia.
authors.forename: Susan
authors.initials: S
authors.lastname: Hoe
authors.forename: Daniela
authors.initials: D
authors.lastname: Traini
authors.forename: Hak-Kim
authors.initials: HK
authors.lastname: Chan
authors.forename: Paul M
authors.initials: PM
authors.lastname: Young
mesh_terms: D000280:Administration, Inhalation; D000420:Albuterol / Q000031:analogs & derivatives / Q000494:pharmacology; D000730:Androstadienes / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004338:Drug Combinations; D000068298:Fluticasone; D000068297:Fluticasone-Salmeterol Drug Combination; D005541:Forced Expiratory Volume; D007700:Kinetics; D036501:Metered Dose Inhalers; D055672:Static Electricity
chemical_list: D000730:Androstadienes; D004338:Drug Combinations; D000068297:Fluticasone-Salmeterol Drug Combination; D000068298:Fluticasone; D000420:Albuterol