title: The effect of actuator nozzle designs on the electrostatic charge generated in pressurised metered dose inhaler aerosols.
abstract: OBJECTIVE
  To investigate the influence of different actuator nozzle designs on aerosol electrostatic charges and aerosol performances for pressurised metered dose inhalers (pMDIs).
  
  
  METHODS
  Four actuator nozzle designs (flat, curved flat, cone and curved cone) were manufactured using insulating thermoplastics (PET and PTFE) and conducting metal (aluminium) materials. Aerosol electrostatic profiles of solution pMDI formulations containing propellant HFA 134a with different ethanol concentration and/or model drug beclomethasone dipropionate (BDP) were studied using a modified electrical low-pressure impactor (ELPI) for all actuator designs and materials. The mass of the deposited drug was analysed using high performance liquid chromatography (HPLC).
  
  
  RESULTS
  Both curved nozzle designs for insulating PET and PTFE actuators significantly influenced aerosol electrostatics and aerosol performance compared with conducting aluminium actuator, where reversed charge polarity and higher throat deposition were observed with pMDI formulation containing BDP. Results are likely due to the changes in plume geometry caused by the curved edge nozzle designs and the bipolar charging nature of insulating materials.
  
  
  CONCLUSIONS
  This study demonstrated that actuator nozzle designs could significantly influence the electrostatic charges profiles and aerosol drug deposition pattern of pMDI aerosols, especially when using insulating thermoplastic materials where bipolar charging is more dominant.
authors.affiliation: Respiratory Technology, Woolcock Institute of Medical Research and Discipline of Pharmacology, Sydney Medical School,, The University of Sydney, Sydney,, NSW, 2037, Australia.
authors.forename: Yang
authors.initials: Y
authors.lastname: Chen
authors.forename: Paul M
authors.initials: PM
authors.lastname: Young
authors.forename: David F
authors.initials: DF
authors.lastname: Fletcher
authors.forename: Hak Kim
authors.initials: HK
authors.lastname: Chan
authors.forename: Edward
authors.initials: E
authors.lastname: Long
authors.forename: David
authors.initials: D
authors.lastname: Lewis
authors.forename: Tanya
authors.initials: T
authors.lastname: Church
authors.forename: Daniela
authors.initials: D
authors.lastname: Traini
mesh_terms: D000335:Aerosol Propellants / Q000737:chemistry; D000336:Aerosols; D000535:Aluminum / Q000737:chemistry*; D001507:Beclomethasone / Q000008:administration & dosage; D004867:Equipment Design; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry; D036501:Metered Dose Inhalers; D011093:Polyethylene Terephthalates / Q000737:chemistry*; D011138:Polytetrafluoroethylene / Q000737:chemistry*; D055672:Static Electricity; D005466:Fluorocarbons
chemical_list: D000335:Aerosol Propellants; D000336:Aerosols; D000535:Aluminum; D001507:Beclomethasone; D006845:Hydrocarbons, Fluorinated; D011093:Polyethylene Terephthalates; D011138:Polytetrafluoroethylene; C094049:apaflurane; D005466:Fluorocarbons