The delivery of aerosolized medication from pressurized metered-dose inhalers (pMDIs) by VHC with facemask that is often prescribed for infants and small children, is influenced by surface electrostatic charge. Our study attempted to examine medication delivery via VHC with facemask attached, using a model infant face (ADAM) based on a Laerdal head mannequin, modified to simulate natural facial texture.
VHCs manufactured from a transparent, electrostatic charge dissipative polymer (AeroChamber Max™ with child mask, Monaghan Medical Corp., Plattsburgh, NY [AC-MAX]) were compared with similar sized VHCs manufactured from non-conducting polymer (OptiChamber® Advantage with medium facemask, Respironics Inc., Cedar Grove, NJ [OPT-ADV]) [n=3-devices/group, 3-replicates/device]. The AC-MAX VHCs were tested out-of-the-package and pre-washed with detergent solution followed by rinsing. The OPTI-ADV VHCs were pre-washed but not rinsed to confer the maximum benefit of detergent coating as a means of reducing electrostatic charge. An electret filter was located immediately behind the lips of the model and breathing simulated at 155-ml tidal volume, 25-breaths/min with inspiration duration of 0.8-s. The facemask was applied with a pressure of 1.6-kg to the face, based on practice at a university pediatric asthma clinic. An acceptable facial seal was confirmed by comparing volumes from the inspiratory flow-time profile determined by a pneumotachograph located at the pMDI adapter of the VHC with that indicated by the breathing simulator. 2-actuations of fluticasone propionate ([FP], 125 μg/actuation, Flovent® HFA, GSK Inc., Canada) were delivered 10 to 12-s apart. The filter was removed from the model and assayed for FP content by HPLC-UV spectrophotometry.
TM via AC-MAX VHCs with no pre-treatment was 55.1 (2.29) μg (mean (95%CI)), comparable with 51.3 (3.29) μg with pre-treatment. TM via OPTI-ADV VHCs was 19.4 (4.76) μg.
The use of electrostatic charge dissipative materials for the VHC is more effective than pre-treatment of a non-conducting VHC by washing in ionic detergent.
Dosing may have to be adjusted to take into account the poorer efficiency of the non-conducting VHC.
J.P. Mitchell, Mark W. Nagel and Jolyon P. Mitchell