Background: Previous in vitro aerosol deposition experiments indicate that the corticosteroid respirable dose from a metered-dose inhaler (MDI) can vary by threefold depending on the specific valved holding chamber (VHC) MDI combination.
Objective: We compared in vitro aerosol deposition from a fluticasone propionate MDI (Flovent, GlaxoSmithKline, Research Triangle Park, NC) to that of the same MDI used in combination with two VHCs (EasiVent, Dey, Napa, Ca; and AeroChamber-Plus, Monaghan Medical Corp, Plattsburgh, NY) to evaluate how these VHCs affect the respirable dose of fluticasone.
Methods: The respirable dose (aerosol particles 1 to 5 microm in size) of fluticasone was determined by sampling 5 x 110-microg actuations from each configuration (MDI alone, MDI plus AeroChamber-Plus, and MDI plus EasiVent) in multiples of ten using a well established, in vitro cascade impactor method. Fluticasone aerosol was washed from individual impactor stages with 50% methanol and quantified via ultraviolet high-pressure liquid chromatography. Differences among outcomes were determined using analysis of variance.
Results: Mean respirable dose from AeroChamber-Plus (47.9 +/- 6.9 microg/actuation) was not different (P > 0.05) from that produced by the MDI alone (50.3 +/- 2.2 microg/actuation). EasiVent respirable dose (27.0 +/- 3.6 microg/actuation) was less than that produced by either the AeroChamber-Plus or the MDI alone (P < 0.001).
Conclusions: VHCs do not display equivalent in vitro performance with a fluticasone MDI. If a patient needs a VHC, clinicians should use available in vitro performance information to aid in selecting the best device.