PURPOSE: This in vitro study evaluated the influence of different breathing patterns on the emitted dose of nebulized arformoterol. Breath simulation experiments used a PARI LC Plus® nebulizer in combination with the Dura-Neb 3000® portable aerosol system. Patterns were selected to mimic the ranges that might be observed in patients with chronic obstructive pulmonary disease (COPD).
METHODS: Four breathing patterns with different tidal volumes (300-650 mL), breath frequencies (10-15 breaths/min), peak inspiratory flow rates (0.25-1.00 L/sec), and inspiratory to expiratory time (I:E) ratios (1:07-1:3.6) were studied using the Active Servo Lung, ASL 5000™. The dose of arformoterol on the inspiratory and expiratory filters, and the residual amount contained in the nebulizer bowl after an 8-minute nebulization period were determined by HPLC. The results are expressed as a percentage of the nominal dose (15 μg).
RESULTS: The inspiratory filter dose increased with longer inspiratory phase of tidal breathing (ranging from 8% to 13%), while the expiratory filter dose remained similar (8-9%) for all 4 breathing patterns. The total emitted filter dose (inspiratory and expiratory combined) for all patterns was <16-21% of the nominal dose. The maximum possible emitted dose of arformoterol, as defined by the amount not retained in the nebulizer bowl, did not exceed 6.42 μg of the nominal 15-μg dose for any of the 4 breathing patterns.
CONCLUSION: These breath simulation experiments demonstrate that only a small proportion (<25%) of the nominal 15-μg arformoterol dose is emitted from the nebulizer apparatus with the 4 breathing patterns studied.
CLINICAL IMPLICATIONS: This study suggests that the emitted dose of arformoterol inhalation solution 15 μg in 2 mL would not be substantially impacted by different breathing patterns during nebulization.
DISCLOSURE: Andrea Bauer, No Product/Research Disclosure Information; Employee I am a full-time employee of Sepracor Inc.