A device, drug package and methodology for using such to generate an aerosol by moving a flowable formulation through a low resistance filter and then through a nozzle comprised of a porous membrane are disclosed. The package is comprised of a collapsible wall portion that forms a container...http://www.google.com/patents/US5829435?utm_source=gb-gplus-sharePatent US5829435 - Prefilter for prevention of clogging of a nozzle in the generation of an aerosol and prevention of administration of undesirable particles 
