IN-VITRO PERFORMANCE OF 3 COMBINATIONS OF SPACERS AND PRESSURIZED METERED-DOSE INHALERS FOR TREATMENT IN CHILDREN

The performance of pressurized metered dose inhalers (pMDIs) and space rs in correct dose recommendations is important, but limited informati on on dose delivery and fine-particle dose from different combinations of spacers and pMDIs is available. In this study, three combinations of spacers and pMDIs were investigated: NebuChamber(R) and AeroChamber (R) with budesonide pMDI and Babyhaler(R) with fluticasone propionate pMDI. Doses were withdrawn onto a filter either with a breathing simul ator (dose to ventilator) or with constant flow (maximal dose). The fi ne-particle dose was assessed with a cascade impactor (Andersen Sample r). The effect of repeated use and cleaning of the spacers on the pass ive fallout of aerosol within the spacers was determined by evacuating the dose on a filter 2, 5, 10 and 30 s after actuating the spray. The drugs were quantified by liquid chromatography. The NebuChamber deliv ered the highest doses, both maximal dose and dose to ventilator. The recovered doses (mean+/-SD) were 55+/-6% and 51+/-2%, respectively, of the delivered dose from the pMDI. The corresponding results for the B abyhaler mere 41+/-7% and 24+/-4% and for the Aerochamber 27+/-3% and 17+/-3%. The passive fallout of aerosol, determined as half-life (t1/2 ) was around similar to 30 s for the NebuChamber, 9-15 s for the Babyh aler and similar to 10 s for the AeroChamber. The present study confir ms that there are significant differences in dose output from differen t combinations of pressurized metered dose inhalers and spacers, with the NebuChamber giving the highest dose, both as delivered dose and in droplets <4.7 mu m. Interactions with the spacer material, dead space in the inspiratory line and entrainment of air during inhalation due to inefficient valve control could account for these differences.