The use of Puffers (MDIs) as Aerosol Delivery Devices

JANA KESAVAN (1), Deborah Schepers (1), Jerold Bottiger (1)

US ARMY Edgewood Chemical Biological Center, Aberdeen Proving Ground

     Abstract Number: 361
     Last modified: May 10, 2010

Abstract
Metered dose inhalers (MDI), also known as puffers, are used to deliver aerosols for medicinal and aerosol research purposes. Puffers can be loaded with many materials such as: Polystyrene Latex (PSL) beads, sodium fluorescein, bacterial spores (alive and dead), viruses, proteins, and other materials.
This study was conducted to determine puffers’ potential usefulness as quantitative aerosol sources, for example, to calibrate instruments. The percentage delivery and inter- and intra-device consistency of the aerosol output delivered by puffers were determined. The output of the puffers was obtained using a variety of actuators and without an actuator. Each puffer's output was collected in a balloon with a 10 mL of solution appropriate for the collection material. The output was quantified by fluorometry or by plating and counting colony forming units (cfu). Puffer output without the actuator gave more consistent results; however, it is not practical to use this way to deliver aerosols to an instrument.
Newly made PSL and sodium fluorescein puffers without the actuator produced 100% of the calculated output and the amount decreased as the particles agglomerated and deposited on the walls over time. Sonication of the puffer resuspended and de-agglomerated the material in the puffers and increased the output. When the bio puffers were more than 2 months old, only 15.5% of the calculated output was recovered for the unsonicated and hand shaken bio-puffers. This low yield may be due to clusters of bacteria that contain many spores being counted as one cfu . This may also be due to adhesion of the bio particles to the walls or loss of culturability. In conclusion, puffers of certain formulations, properly sonicated before each use, can be used as aerosol delivery devices to calibrate instruments with respect to particle size, and as useful but not quantitative aerosol delivery devices in testing.