A pear shaped non-electrostatic spacer, composed of steel with a volume of 250 ml and equipped with a facemask containing integrated inlet and outlet valves for inspiration and expiration, was compared with three plastic spacers. The plastic spacers were primed with repeated puffs from a budesonide pressurised metered dose inhaler (p-MDI) to minimise the electrostatic charge on the plastic. The procedure prolonged the half life (tm12) of the aerosol in the Nebuhaler from nine to 32 seconds. A normal cleaning procedure reduced the aerosol t/2 back to baseline.The t/ of the aerosol in the metal spacer was 27 seconds and independent of the use of p-MDI. In vitro the maximum dose of budesonide from a p-MDI, expressed as a percentage of the nominal dose, was 56% from the non-electrostatic spacer, 61% from the Nebuhaler, 450/0 from the Babyhaler, and 30% from the AeroChamber. In 124 children, age 6 months to 6 years, suspected to have asthma the non-electrostatic spacer delivered a mean total dose of budesonide aerosol of 39% of the nominal dose, which was significantly higher than the Babyhaler (28%), the Nebuhaler (21%), and the AeroChamber (19%). These differences were most pronounced in children younger than 4 years. The improved dose delivery from the small volume non-electrostatic spacer is probably related to the non-electrostatic spacer material and the valves which assured unidirectional airflow from the spacer without adding any dead space in the inspiratory channel. The non-electrostatic spacer should improve the cost effectiveness of aerosol treatment and, as the counteracting effects of priming and recharging ofthe plastic from cleaning are avoided, should deliver a more reliable dose. (Arch Dis Child 1995; 73: 226-230)
aaPressurized metered dose inhalers (pMDIs) with spacers adapted for use in young children have gained wide popularity. To provide optimal drug delivery, spacer design is critical [1]. The spacer causes important changes in the output in terms of total dose, as well as in terms of small-droplet mass. The mass of drug in small droplets of less than approximately 5 µm is traditionally considered to be the dose fraction most likely to reflect the dose available to the lungs [2]. Effects, side-effects and cost-effectiveness are mainly related to the lung dose [3,4] and are, therefore, strictly dependent on the combination of pMDI and spacer. The unity of pMDI plus spacer should consequently be stressed, and it would be desirable to relate dose recommendations to the output from the pMDI and spacer rather than simply to the nominal dose of the pMDI. However, until recently only limited information has been available on the small-droplet mass provided by different combinations of pMDI and spacer for young children.The aim of the present study was to compare the delivered dose, as well as the output in small droplets, from three spacers developed for the treatment of young children: NebuChamber® ("Non-electrostatic metal spacer") Babyhaler® and AeroChamber®. Materials and methods Overall designIn this study, which is divided into three parts, three combinations of spacers and pMDIs were investigated (NebuChamber and AeroChamber with budesonide pMDI and Babyhaler with fluticasone propionate pMDI): 1) doses were withdrawn onto a filter either with a breathing simulator (dose to ventilator) or with constant flow (maximal dose); 2) the fine-particle dose was assessed with a cascade impactor (Andersen Sampler); and 3) the effect of repeated use and cleaning of the spacers on the passive 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 SpacersIn figure 1, schematic drawings are shown with arrows indicating the inhalation and exhalation paths. Dead space, discussed below, is a volume in the inspiratory line, common to both inhalation and exhalation. The drug-containing aerosol trapped in this volume will be lost during In vitro performance of three combinations of spacers and pressurized metered dose inhalers for treatment in children. E. Berg, J. Madsen, H. Bisgaard. ERS Journals Ltd 1998.ABSTRACT: The performance of pressurized metered dose inhalers (pMDIs) and spacers in correct dose recommendations is important, but limited information 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® and AeroChamber® with budesonide pMDI and Babyhaler® with fluticasone propionate pMDI. Doses were withdrawn onto a filter either with a breathing simulator (dose to ventilator) or with constant flow (maximal dose). The fine-particle dose was assessed with a cascade impactor (Andersen Sampler). The effect of repeated use an...
We have quantified in vitro the influence of the facemask on the amount of drug delivered (e.g., inhaled mass) by jet nebulizer and pressurized metered dose inhaler (pMDI) valved holding chamber (VHC) combinations (non-detergent-coated and detergent-coated). Pediatric breathing patterns were used with a breathing simulator, which was connected to a face onto which each device was positioned. An inhaled mass filter interposed between the simulator and the face captured the aerosolized drug. Budesonide inhalation suspension (0.25 mg) was used with the jet nebulizers and fluticasone propionate (220 microg) pMDI with the VHCs. Maximal drug delivery was measured using constant flow through each device. Breathing pattern effects were assessed for sealed devices (no leaks) and with facemasks (possible leaks at the facemask). Inhaled mass from both nebulizers and pMDI VHCs was affected by breathing pattern, but compared to nebulizers the pMDI VHCs were significantly more variable and sensitive to several factors. The influence of VHC conditioning combined with effects of breathing pattern resulted in the inhaled mass ranging from 0.7 +/- 0.5 to 53.3 +/- 6.2%. Nebulizers were less variable (9.6 +/- 0.7 to 24.3 +/- 3.1%). Detergent coating of VHC markedly increased the inhaled mass and reproducibility of drug delivery (27.2 +/- 1.4 to 53.3 +/- 6.2%) for pMDI VHC combinations, but these effects were lost in the presence of facemasks. Using pediatric patterns of breathing, nebulizer/facemask combinations delivered 4.1 +/- 0.8 to 19.3 +/- 2.3% of the label dose while pMDI and detergent-coated VHC delivered 4.0 +/- 1.6 to 28.6 +/- 2.5%. Facemask seal is a key factor in drug delivery. Leaks around the facemask reduce drug delivery and for pMDI VHCs can negate effects of detergent coating.
Size distributions of droplets generated by nebulizers are difficult to determine because of evaporation after aerosolization. We describe a method whereby a Next Generation Pharmaceutical Impactor (NGI; MSP Corporation, Shoreview, MN) is refrigerated at 5 degrees C before connecting it to the nebulizer in order to ensure an environment inside the NGI at close to 100% relative humidity (RH). This, in turn, reduces droplet evaporation between the nebulizer and impaction. The method development was performed with a Pari LC Plus jet nebulizer operated at 2.0 bar, with the NGI set at a flow rate of 15 L/min and with salbutamol 5.0 mg/mL as the test solution. The droplet size distributions were expressed in terms of mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD). Variation in test conditions showed that the NGI should be cooled for at least 90 min, that nebulization should be started within 5 min after removal from the refrigerator, and that coating of collecting cups to prevent "bouncing" is not necessary. Variation of ambient temperature and humidity had no relevant effect on results. MMAD and GSD results showed that refrigeration of the NGI resulted in droplet size distributions that are likely to reflect those originally delivered at the mouthpiece by the nebulizer. The method was shown to be robust, accurate with recovery of test solutions exceeding 99%, reproducible, and to be suitable for use with a wide range of commercially available nebulizers.
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