2002 OPEN FORUM Abstracts
COMPARISON OF PERFORMANCE OF TWO VALVED HOLDING CHAMBERS (VHCs) WITH DELAY BETWEEN METERED DOSE INHALER ACTUATION AND USE
P. Mitchell Ph.D, Sara-Lou Bates, Cathy C. Doyle B.Sc, and Mark W. Nagel
Trudell Medical Aerosol Laboratory, London, Canada
VHCs are recommended for use with pressurized metered-dose inhalers (pMDIs) for those patients who may delay the onset of inhalation after pMDI actuation. A draft Canadian (CAN/CSA) Standard on Spacers and Holding Chambers (expected publication, 2002) has recommended that in vitro performance testing be undertaken with a 2 s delay to simulate this behavior. We compared the performance of two similar sized VHCs (AeroChamber Plusª , Monaghan Medical Corp., Plattsburgh, NY and PrimeAire®, Thayer Medical, Tucson, AZ) (n = 4 devices/group) with a 2 s delay between actuation and sampling into an Andersen 8-stage cascade impactor equipped with USP Induction port. Each VHC was washed with an ionic detergent, rinsed and drip-dried to minimize the influence of electrostatic charge. The impactor was operated at 28.3 ± 0.5 L/min in accordance with <601> of the US Pharmacopeia, representative of the inspiratory flow rate range seen in adult patients. A purpose-built apparatus enabled the delay interval to be reproduced to within 0.1 s. 5-doses of fluticasone propionate (FP) (Flovent® 110, GSK Canada Inc.) were initially delivered from a pre-primed and shaken pMDI canister at 30-s intervals via the VHC into the induction port of the impactor. The induction port and stages of the impactor and the VHC were subsequently assayed for FP by HPLC UV spectrophotometry.
Measurements of fine particle dose (FPD particles < 4.7 mm aerodynamic diameter) and total emitted dose (TED) are summarized in the table. Fine particle fraction (FPF) is the ratio of FPD/TED, expressed as a percentage.
AeroChamber Plusª VHC
|TED (mg)||14.2 ± 1.8||31.2 ± 5.4|
|FPD (mg)||13.3 ± 1.9||30.1 ± 5.3|
|FPF (%)||93.6 ± 2.7||96.3 ± 0.6|
mean ± S.D
As expected, both types of VHC largely eliminated coarse particles, with similar values of FPF for this formulation (p = 0.10). However, both TED and FPD from the AeroChamber Plus? VHCs were greater than their equivalent values from the PrimeAire® VHCs [un-paired t-test, p< 0.001].
The introduction of
a delay to mimic the uncoordinated patient resulted in significantly reduced
output from the PrimeAire® VHC. The clinical
significance of these results remains to be explored.