2001 OPEN FORUM Abstracts
ANEW VALVED HOLDING CHAMBER (VHC) WITH POSITIVE EXPIRATORY PRESSURE
Jolyon P. Mitchell,Sara-Lou Bates, Kimberly J. Wiersema, MarkW. Nagel, Robert W. Morton and Daniel K. Engelbreth Trudell Medical Aerosol Laboratory,London, Canada
Background:There is increasing interest in the application of positive expiratory pressuretherapy in conjunction with delivery of medication to maintain airway patencyfor patients with broncho-constrictive diseases, such as asthma and COPD. Valvedholding chambers (VHCs) permit patients with imperfect coordination to use metereddose inhalers (MDIs) effectively and minimize systemic absorption of drug depositedas coarse particles in the upper respiratory tract. We compared the in vitroperformance of a new VHC with positive expiratory pressure capability (AeroPEP?VHC, Monaghan Medical Corp., Plattsburgh, NY (n=5 devices)) with that of theAeroChamber Plus? VHC for the delivery of an anticholinergic formulation(Atrovent®: 18 µg/dose ipratropium bromide (IPR) ex actuator mouthpieceof the pMDI, Boehringer-Ingelheim Pharmaceuticals Inc.).
Methods: EachVHC was washed with an ionic detergent and drip-dried to minimize the influenceof electrostatic charge. Measurements of fine particle dose (FPD ? particles< 4.7 mm aerodynamic diameter) and total emitted dose (ED) were made withan Andersen 8-stage cascade impactor at 28.3 ± 0.5 l/min, representative ofinspiratory flow rates seen in adult patients. 5-doses were initially deliveredfrom a pre-primed and shaken pMDI canister at 45-s intervals directly into theinduction port of the impactor (5 replicates). The procedure was undertaken(1 measurement with each VHC), with the door position of the AeroPEP? VHC setat ?0? (minimum positive expiratory pressure), ?3? (mid-way) and ?6? (maximum).The stages of the impactor and the VHC were then assayed for IPR by HPLC ?UVspectrophotometry.
Results: mean± S.D
|AeroPEP?VHC (door position)||AeroChamberPlus? VHC|
|ED (mg)||13.4 ± 0.6||13.7 ± 0.3||13.3 ± 0.4||11.2 ± 0.7|
|FPD (mg)||9.4 ± 0.6||9.7 ± 0.3||9.3 ± 0.4||8.6 ± 0.6|
|FPF (%)||70.2 ± 1.7||70.8 ± 1.0||70.2 ± 1.4||76.3 ± 1.4|
Discussion: Thedoor position had no impact on any of the performance measures (1-way repeatedmeasures ANOVA, p ³ 0.39. The differences between ED and FPD for the AeroPEPªVHC (all door positions) and AeroChamber Plusª VHCs compared to equivalent valuesfor the AeroChamber Plusª VHCs were small (p ² 0.014) and within the normalrange of variability with these devices.
Conclusion: Thesemeasurements confirm that the performance of the AeroPEPª VHC on inhalationwas not affected by the presence of the positive expiratory pressure featurethat operates only when the patient exhales.