Particularities of deposition of two ICS-LABA fixed dose combination dry powder aerosol drugs in the airways of COPD patients

The aim of this study was to analyse the effect of breathing parameters, age, gender and disease status on the lung doses of the two ICS + LABA fixed combination dry powder drugs. Breathing parameters of 113 COPD patients were measured while inhaling through emptied NEXThaler® and Ellipta® inhalers and the corresponding lung doses were calculated. Lung dose of Foster® NEXThaler® was superior to the lung dose of Relvar® Ellipta® in around 85 % of the patients. The average value of the ratio of bronchiolar to bronchial deposition fractions was 5.0 for Foster® NEXThaler® and 2.6 for Relvar® Ellipta®. Lung dose was sensitive to the inhalation parameters, such as peak inhalation flow, inhaled volume and breath-hold time. For both studied drugs the dose to the lungs was relatively high for moderate PIF values, but it declined for low (<35 L/min) and high (>95 L/min) PIFs. The lung dose increased by the increase of the inhaled volume, but saturated over 1.0 L of inhaled air. Longer breath-hold time led to higher lung deposition, but the dependence was drug-specific. FEV₁ (%) and FEV₁/FVC (%) did not influence the lung dose significantly (p = 0.05). Exacerbating patients had lower lung doses (28.8 ± 5.8 % for Foster® NEXThaler® and 23.7 ± 3.8 % for Relvar® Ellipta®) than their non-exacerbating counterparts (33.7 ± 6.1 % for Foster® NEXThaler® and for 24.9 ± 3.9 % for Relvar® Ellipta®). The exact clinical consequences of the differences between the deposition distributions of the two drugs could be assessed only by systematic clinical trials.