Assessment of a cyclone-type spacer device for use in dry powder inhalation

Dry powder inhalers (DPIs) are used widely in asthma and chronic obstructive pulmonary disease therapies. However, the lung deposition from DPIs is highly variable and patients with poor lung function can struggle to achieve a sufficient inhalation rate. The aim of this study was to investigate whether a cyclone spacer device could improve the in vitro drug delivery performance of a commercial DPI. The aerosolization of a salbutamol sulphate/lactose blend was studied at 45 Lmin-1 and 60 Lmin-1 using the Cyclohaler (DPI), with and without a Perspex cyclone device which was manufactured in-house. Deposition of particles in the next generation impactor and within the devices was determined by high performance liquid chromatography, and aerosol emission was studied using laser diffraction analysis. The % emission from the DPI was unchanged by the addition of the cyclone at 45 Lmin-1 and 60 Lmin-1. Dose deposition in the cyclone was high at both flow rates, however the fine particle fractions (FPF) as a % of the doses emitted from the DPI were identical with and without the cyclone in place. Comparing the dose depositing in the impactor (equivalent to an inhaled dose), FPFs were substantially higher when the cyclone was employed (e.g. 92.2 ± 7.7% with cyclone vs. 27.9 ± 3.5% without cyclone at 45 Lmin-1). The mass median diameters of particles emitted from the cyclone were also dramatically decreased compared to the DPI alone. This work has shown the potential of employing a cyclone-type spacer to improve inhaled drug delivery.