The Science Journal of the American Association for Respiratory Care

2004 OPEN FORUM Abstracts

IMPROVED PERFORMANCE FROM A VALVED HOLDING CHAMBER (VHC) WITH BODY MANUFACTURED FROM A TRANSPARENT, BUT ELECTROSTATIC CHARGE DISSIPATIVE POLYMER

Jolyon P. Mitchell Ph.D, Kimberly J. Wiersema B.A., Cathy C. Doyle B.Sc, and Mark W. Nagel HB.Sc Trudell Medical Aerosol Laboratory, London, Canada

Particle deposition caused by electrostatic attraction to the walls of VHCs made from non-conducting polymer can significantly reduce pressurized metered dose inhaler (pMDI) medication delivery, especially at first use (1). This study explored the potential for improved performance with a new VHC with body manufactured from a transparent custom charge dissipative polymer (AeroChamber Max™, Monaghan Medical Corp., Plattsburgh, NY), compared with a conventional transparent, but non-conducting VHC (ProChamber™, Respironics Inc., Cedar Grove, NJ). Before testing, both groups of devices (n=3/group) were pre-washed in ionic detergent following each manufacturer’s instructions. Fine particle mass/actuation (FPM), based on particles < 4.7 µm aerodynamic diameter, was determined by Andersen 8-stage cascade impactor at 28.3 L/min ± 5% in accordance with <601> of the US Pharmacopeia. A 2-s delay was introduced between pMDI actuation and sampling via the impactor to simulate use by poorly coordinated patients. 15-actuations of Combivent® (Boehringer-Ingelheim (Canada) Ltd., Mississauga, ON (18 µg ipratropium bromide (IPR) + 90 µg albuterol base equivalent (ALB)) were delivered at 30-s intervals from a pre-primed canister. This formulation carried a significant electrostatic charge (+170 ± 80 pC (mean ± SD)), based on 5 separate actuations from a single pMDI into a Faraday cup electrometer. Values of FPM (mean ± SD) are summarized in the Table

VHC type FPM (µg) Mass Retained by VHC (µg)
ALB IPR ALB IPR
AeroChamber Max™ 41.4 ± 1.7 8.9 ± 0.5 15.5 ± 2.9 4.1 ± 0.3
ProChamber™ 18.1 ± 4.0 3.6 ± 0.8 37.8 ± 3.9 9.5 ± 0.9

FPM from the AeroChamber Max™ VHCs was significantly greater than that from the ProChamber™ VHCs (un-paired t-test, p < 0.001), and was associated with decreased retention of both ALB and IPR by the VHC by the former chamber (p ≤ 0.001). The use of charge dissipative materials is more effective than pre-washing a non-conducting device for the delivery of this formulation, and is likely to lead to a better therapeutic outcome for the uncoordinated patient prescribed a VHC.

(1) Piérart, F., Wildhaber, J.H., Vrancken, I. et al., Eur. Respir J. 1999;13:673-678.

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