The Science Journal of the American Association for Respiratory Care

2000 OPEN FORUM Abstracts

DELIVERY OF ALBUTEROL/IPRATROPIUM BROMIDE VIA A SMALL VOLUME VALVED HOLDING CHAMBER (VHC)

Jolyon P. Mitchell, Sara-Lou Bates, Kimberly J. Wiersema, Mark W. Nagel, Robert W. Morton and James N. Schmidt Trudell Medical Aerosol Laboratory, London, Canada

Background: Valved holding chambers (VHCs) permit patients with imperfect coordination to use metered dose inhalers (MDIs) effectively and minimize systemic absorption of drug deposited as coarse particles in the upper respiratory tract. We compared the in vitro performance of a 149 ml small volume VHC (AeroChamber?-Plus VHC (AC+), Monaghan Medical Corp., Plattsburgh, NY (n=5 devices)) with that of the pMDI alone for the delivery of a combination b-agonist/anticholinergic formulation (Combivent®: 103 mg/dose salbutamol (albuterol) sulfate (SAL) + 18 mg/dose ipratropium bromide (IPR) ex actuator mouthpiece of the pMDI, Boehringer-Ingelheim Pharmaceuticals Inc.).

Methods: Each VHC was washed with an ionic detergent and drip-dried prior to test to minimize the influence of electrostatic charge. Measurements of fine particle dose (FPD - particles < 4.7 mm aerodynamic diameter) and total emitted dose (ED) were made with an Andersen 8-stage cascade impactor at 28.3 ± 0.5 l/min, representative of inspiratory flow rates seen in adult patients. 5-doses were initially delivered from a pre-primed and shaken pMDI canister at 45-s intervals directly into the induction port of the impactor (5 replicates). The procedure was repeated (1 measurement with each VHC), with the pMDI inserted into the VHC adapter. The stages of the impactor and the VHC were then assayed for SAL and IPR as separate components by HPLC -UV spectrophotometry.

Results: mean ± S.D

IPR SAL
pMDI alone pMDI with AC+ pMDI alone pMDI with AC+
ED (% label claim dose) 86.0 ± 2.0 51.0 ± 5.0 86.1 ± 1.5 59.7 ± 4.1
FPD (% label claim dose) 35.0 ± 2.0 47.0 ± 4.5 46.2 ± 2.7 56.2 ± 3.6
FPF (%) 40.8 ± 2.8 90.5 ± 1.3 53.6 ± 2.9 94.1 ± 1.6

Discussion: ED of both IPR and SAL components was decreased by the presence of the VHC [un-paired t-test, p < 0.001]. However, FPD of both components was increased compared with the pMDI alone [p < 0.004], and the fine particle fraction (FPF) of either component delivered by the VHC was close to 90% of ED. Conclusion: The VHC markedly reduced the portion of the dose from either component of Combivent® contained as coarse particles. At the same time, FPD was better than that available from the pMDI alone. The AC+ VHC greatly reduced the proportion of the dose delivered as coarse particles > 5 mm aerodynamic diameter that have little therapeutic benefit to patients with chronic lung disease.

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