Previous in vitro aerosol experiments suggest the quantity of corticosteroid inhaled by asthma patients via metered-dose inhaler (MDI) can vary several fold depending on the valved holding chamber (VHC). We compared in vitro aerosol deposition from a fluticasone MDI (Flovent®, GlaxoSmithKline) to the same MDI in combination with an AeroChamber-Plus™ (Monaghan) VHC, the OptiChamber® (Respironics) VHC, and the OptiChamber®-Advantage (Respironics) VHC, in order to asses how these VHCs affect the respirable quantity of fluticasone inhaled from a MDI.
The respirable dose (aerosol particles 1-5 μm in size) of fluticasone was determined by sampling 5 runs of five 110 μg actuations from each configuration (MDI alone, MDI + AeroChamber-Plus™, MDI + OptiChamber®, MDI + OptiChamber®-Advantage) using a well-established in vitro cascade impactor method (USP-24;2000:1895-1912). Fluticasone aerosol was washed from individual impactor stages with 50% methanol and quantified via HPLC-UV. Differences among the primary outcome were determined using ANOVA.
Mean fluticasone respirable dose from AeroChamber-Plus™ (45.3 ± 1.8 μg/ actuation) and OptiChamber® (38.1 ± 8.7 μg/ actuation) were no different (p > 0.05) from the respirable dose produced by the MDI alone (46.7 ± 9.7 μg/ actuation). OptiChamber®-Advantage respirable dose (32.1 ± 1.6 μg/ actuation) was significantly less than that produced by either the AeroChamber-Plus™ or the MDI alone (p < 0.05) but not different from OptiChamber® (p > 0.05).
In vitro respirable dose of fluticasone aerosol from the OptiChamber®-Advantage VHC was 40-45% less than from the MDI alone or the AeroChamber-Plus™ VHC.
In asthmatics on fluticasone MDI needing a VHC, AeroChamber-Plus™ or OptiChamber® would be a better choice over OptiChamber®-Advantage since they do not change the respirable dose compared to MDI alone.
M.J. Asmus, Monaghan Medical Corporation, Grant monies.