Inhalation through two mini-spacer-like inhaler technique training devices: An in-vitro aerosol delivery comparative study

<bold>Introduction:</bold> Patients are recommended to inhale slowly (30 L/min) over 5 sec through pressurized metered dose inhalers (pMDIs)¹. Poor pMDI use is common among patients. Flo-Tone^® (FT) and Flo-Tone controlled resistance^® (FTCR) (Clement Clarke International, UK) are mini-spacer pMDI technique training devices with audible feedback to guide patients to a co-ordinated inhalation through pMDIs. <bold>Methods:</bold> 30 and 90 L/min inhalation flow rates over 2 and 5 sec were used to compare aerosol delivery of salbutamol from Ventolin Evohaler connected to FT and FTCR. The Next Generation Impactor (NGI) was used to evaluate the delivered dose (DD), fine particle fraction (FPF), mass median aerodynamic diameter (MMAD). Deposition on FT, FTCR and NGI’s induction port (IP) were also compared. <bold>Results:</bold> Comparing FT to FTCR, no significant differences in DD except at 90 L/min over 5 sec (88.2 vs 71.2 µg). The MMAD was significantly different at only 30 L/min over 5 sec (2.44 vs 3.0 µm) and 90 L/min over 2 sec (2.42 vs 2.17). The FPF was similar. FTCR retained less drug and resulted in less IP impaction. <bold>Conclusion:</bold> The FT and FTCR delivered comparable salbutamol doses and fine particles (≤5 µm) under optimal and suboptimal inhalation through pMDI. The FTCR was privileged with lower throat deposition. Ultimately, these devices are intended to improve and maintain patients’ correct pMDI use. References: 1. Laube, B., Janssens, H., de Jongh, F et al. (2011). Eur Respir J 37, 1308–1331. doi: 10.1183/09031936.00166410