Higher lung deposition with Respimat Soft Mist inhaler than HFA-MDI in COPD patients with poor technique

Aerosols delivered by Respimat Soft Mist Inhaler (SMI) are slower-moving and longer-lasting than those from pressurized metered-dose inhalers (pMDIs), improving the efficiency of pulmonary drug delivery to patients. In this four-way cross-over study, adults with chronic obstructive pulmonary disease (COPD) and with poor pMDI technique received radiolabelled Berodual (fenoterol hydrobromide 50 microg/ipratropium bromide 20 microg) via Respimat SMI or hydrofluoroalkane (HFA)-MDI (randomized order) on test days 1 and 2, with no inhaler technique training. The procedure was repeated on test days 3 and 4 after training. Deposition was measured by gamma scintigraphy. All 13 patients entered (9 males, mean age 62 years; FEV1 46% of predicted) inhaled too fast at screening (peak inspiratory flow rate [IF]: 69-161 L/min). Whole lung deposition was higher with Respimat SMI than with pMDI for untrained (37% of delivered dose vs 21% of metered dose) and trained patients (53% of delivered vs 21% of metered dose) (P(Sign-Test) = 0.15; P(ANOVA) < 0.05). Training also improved inhalation profiles (slower average and peak IF as well as longer breath-hold time). Drug delivery to the lungs with Respimat SMI is more efficient than with pMDI, even with poor inhaler technique. Teaching patients to hold their breath as well as to inhale slowly and deeply increased further lung deposition using Respimat SMI.