Feasibility of Drug Delivery to the Respiratory Tract by a Mechanical Micro Spray Pump

A hand actuated, propellant free spray device is being developed which may be suitable for medical inhalation therapy. The purpose was to evaluate the feasibility of the mechanical micro spray pump to produce a fine spray whose droplets were suitable for inhalation. The physical and technical requirements have been achieved using an air blast nozzle which has been improved by changing the geometry and therefore the dynamic properties within the spray nozzle. The generation of particles above 50 mum in diameter was suppressed and the injection time of the spray increased. These features resulted in a finer and more uniform spray. In-vivo experiments were conducted, where 15 mul per stroke of a 99mTc labeled saline solution was delivered to test persons. The activity was measured by gamma-scintigraphy. It was observed that without and with a spacer, a respective thoracic deposition of 8 %vol and 13 %vol was achieved on average.