Selecting an accessory device with a metered-dose inhaler: Variable influence of accessory devices on fine particle dose, throat deposition, and drugdelivery with asynchronous actuation from a metered-dose inhaler

Accessory devices reduce common problems with metered-dose inhalers (MDIs), namely high oropharyngeal deposition of aerosol and incoordination between actuation and inhalation by the patient. The objective of this study was t o systematically compare the performance of various accessory devices in vi tro. MDIs were tested alone or in combination with four spacers (Toilet pap er roll, Ellipse, Optihaler, Myst Assist) and five holding chambers (Aeroch amber, Optichamber, Aerosol Cloud Enhancer, Medispacer, and Inspirease). An Anderson cascade impactor was used to measure aerosol mass median aerodyna mic diameter (MMAD) and fine particle dose (MMAD < 4.7 mum). In separate ex periments, the influence of asynchronous MDI actuation on drug delivery was determined with a simulated spontaneous breathing model. Compared with the MDI alone, all of the accessory devices reduced aerosol MMAD and increased lung-throat ratio (fine particle dose/throat impaction; p < 0.05 for both parameters). The fine particle dose of albuterol was 40% higher with the El lipse (p < 0.01), was equivalent with the Toilet Paper Roll, Aerochamber, O ptichamber, and Medispacer, and was 33-56% lower with the Optihaler, Myst A ssist, Aerosol Cloud Enhancer, and Inspirease (p < 0.03). MDI actuation in synchrony with inspiration produced highest drug delivery; when MDI actuati on occurred I-sec before inspiration or during exhalation, decrease in drug delivery with holding chambers (10-40% reduction) was less than that with spacers (40-90% reduction). Accessory device selection is complicated by va riability in performance between devices, and in the performance of each de vice in different clinical settings. In vitro characterization of a MDI and accessory device could guide appropriate device selection in various clini cal settings.