We have quantified in vitro the influence of the facemask on the amount of drug delivered
(e.g., inhaled mass) by jet nebulizer and pressurized metered dose inhaler (pMDI) valved
holding chamber (VHC) combinations (non-detergent-coated and detergent-coated). Pediatric
breathing patterns were used with a breathing simulator, which was connected to a face onto
which each device was positioned. An inhaled mass filter interposed between the simulator
and the face captured the aerosolized drug. Budesonide inhalation suspension (0.25 mg) was
used with the jet nebulizers and fluticasone propionate (220 µg) pMDI with the VHCs. Maximal
drug delivery was measured using constant flow through each device. Breathing pattern
effects were assessed for sealed devices (no leaks) and with facemasks (possible leaks at the
facemask). Inhaled mass from both nebulizers and pMDI VHCs was affected by breathing
pattern, but compared to nebulizers the pMDI VHCs were significantly more variable and
sensitive to several factors. The influence of VHC conditioning combined with effects of
breathing pattern resulted in the inhaled mass ranging from 0.7 ± 0.5 to 53.3 ± 6.2%. Nebulizers
were less variable (9.6 ± 0.7 to 24.3 ± 3.1%). Detergent coating of VHC markedly increased
the inhaled mass and reproducibility of drug delivery (27.2 ± 1.4 to 53.3 ± 6.2%) for
pMDI VHC combinations, but these effects were lost in the presence of facemasks. Using pediatric
patterns of breathing, nebulizer/facemask combinations delivered 4.1 ± 0.8 to 19.3 ±
2.3% of the label dose while pMDI and detergent-coated VHC delivered 4.0 ± 1.6 to 28.6 ±
2.5%. Facemask seal is a key factor in drug delivery. Leaks around the facemask reduce drug
delivery and for pMDI VHCs can negate effects of detergent coating.
