Abstract
There is increasing interest in the use of so-called ‘extrafine’ aerosols to target the small airways in the management of asthma and COPD. Using previously presented deposition data, we assessed whether submicron (<1μm) particles can improve central and deep lung deposition. Our data show instead that particles in the range 1–3μm are much more relevant in this respect. Based on this finding the Symbicort Turbuhaler, Seretide Diskus, Rolenium Elpenhaler and Foster (Fostair) NEXThaler ICS/LABA combination DPIs were tested in vitro as a function of the pressure drop (2, 4 and 6kPa) across the inhaler. Obtained fine particle fractions (FPFs) <5μm (as percent of label claim) were divided into subfractions <1, 1–3 and 3–5μm. Differences of up to a factor of 4 were found between the best (Turbuhaler) and worst performing DPI (Elpenhaler), particularly for the FPF in the size range 1–3μm. The NEXThaler, described as delivering ‘extrafine’ particles, did not appear to be superior in this size range. The marked differences in amount and size distribution of the aerosols between the devices in this study must cause significant differences in the total lung dose and drug distribution over the airways.
Highlights
Asthma and chronic obstructive pulmonary disease (COPD) are characterized by airflow obstruction and chronic inflammation of the respiratory airways
To make a comparative evaluation regarding the most favorable size distribution for total and deep lung deposition possible, we tested four Inhaled corticosteroids (ICSs)-long acting beta2-agonist (LABA) combination dry powder inhaler (DPI) under precisely the same conditions (2, 4 and 6 kPa) and used the same data presentation for all devices by computing mass fractions of the delivered aerosols in the size ranges < 1, 1–3 and 3–5 lm. This is breaking with a tradition according to which only mass median aerodynamic diameter (MMAD) of delivered aerosols are given
The steep increase in the fraction exhaled with decreasing particle diameter for submicron particles shown in Fig. 3 suggests that particles
Summary
Asthma and chronic obstructive pulmonary disease (COPD) are characterized by airflow obstruction and chronic inflammation of the respiratory airways. Inhaled corticosteroids (ICSs) are the cornerstone of asthma and, to a lesser degree, COPD therapy because of their long-term efficacy and safety [1] but optimal effects may be expected when an ICS is administered in combination with a long acting beta2-agonist (LABA) [2]. This has resulted in an increasing number of ICS/LABA inhalers becoming available. The origin of this idea may have q Foster/FostairÒ NEXThalerÒ, SymbicortÒ TurbuhalerÒ, SeretideÒ DiskusÒ, and RoleniumÒ ElpenhalerÒ are registered trademarks of the manufacturer
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