Investigating The Potential Of An Airflow-Indicating Miniature Spacer to Manage Human Factor Barriers To Effective Metered Dose Inhaler Use.

S Hakim, R Bruin, D Murnane

Pressurized metered dose inhalers (pMDIs) qualify as ‘old technologies’ with the device rapidly approaching its 60th anniversary. Despite their popularity, pMDIs are associated with several difficulties, including extensive throat deposition and the requirement to coordinate actuation and inhalation. The Flo-Tone is a miniaturized spacer which aims to promote coordination by providing an aural stimulus to patients of inhalation. The aim of this work was to investigate aerosolization of two suspension pMDIs when combined with the Flo-Tone. Aerosolization was studied using the next generation impactor at 30 or 60 Lmin-1 for salbutamol sulphate (SS – Ventolin Evohaler) and fluticasone propionate (FP – Flixotide Evohaler) products. Poor co-ordination was simulated for FP by delaying initiation of airflow through the NGI for 0.5 – 1.0 s after actuation. Throat deposition was reduced at both flow rates (e.g. SS 23.0 ± 4.1 % to 11.9 ± 4.3 % at 30 Lmin-1) for both formulations (e.g. FP 78.9 ± 3.9 % (poor coordination) to 15.73 ± 2.09 %). The fine particle fractions (FPF %ED) were similar for FP with (34.4 ± 2.5 %) and without the spacer (37.9 ± 3.1 %). It was found that the FPF %ED for SS increased when the airflow rate was increased from 30 to 60 Lmin-1(46.1 ± 2.4 % vs. 60.8 ± 2.3 %), however using the Flo-Tone overcame this effect. An airflow-indicating spacer may offer benefits by improving coordination, but was also effective at minimizing ballistic in vitro deposition, albeit with potential dependence on formulation identity.

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