VHCs are prescribed for patients that have difficulty coordinating pressurized metered-dose inhaler (pMDI) use, frequently resulting in delayed inhalation following inhaler actuation. Our study introduced a realistic 2-second delay, comparing delivery of a beta-2 agonist via VHCs of similar size (n=5/group), one manufactured from cardboard (LiteAire™, Thayer Medical, Tucson, AZ –160-ml) the other from rigid polymer (AeroChamber Plus®, Monaghan Medical Corp., Syracuse, NY –150-ml).
The AeroChamber Plus® VHCs were pretreated by washing in water containing a mild ionic detergent, rinsed and drip-dried, as recommended prior to use. The LiteAire™ VHCs were assembled and used in accordance with manufacturer’s instructions. Each VHC was tested using an Andersen 8-stage impactor with USP Induction Port operated at 28.3±0.5 L/min, representative of flow rates seen with adult patients. A shutter that interfaced between the VHC mouthpiece and induction port entrance was used to simulate a 2-s delay interval between pMDI actuation and the onset of sampling. The shutter moved to allow flow from the VHC to the impactor only after the defined delay. 5-actuations of albuterol (Ratiopharm, Mississauga, Canada, 100 μg/dose albuterol base equivalent ex metering valve) were delivered from a pre-primed and shaken pMDI canister at 30-s intervals. The induction port and stages of the impactor were subsequently assayed for albuterol by HPLC-UV spectrophotometry. Benchmark measurements were also made with the pMDI alone.
Fine particle mass/actuation ((FPM) <4.7 μm aerodynamic diameter (mean (95% CI)) was 27.8 (4.2) μg (pMDI alone), 21.7 (5.0) μg (AeroChamber Plus® VHC) and 13.9 (4.2) μg (LiteAire™ VHC).
FPM(pMDI-alone) represents delivery with perfect inhaler technique. The AeroChamber Plus® VHC delivered nearly 80% FPM(pMDI-alone) with a 2-s delay, but the corresponding delivery via the LiteAire™ VHC was only 50% FPM(pMDI-alone).
Dosing may have to be adjusted to take into account the poorer efficiency of the cardboard VHC, considering the likelihood of imperfect coordination.
Dominic Coppolo, Employee All of the authors are employees of companies in the Trudell Medical Group. These companies manufacture the AeroChamber Plus® VHC