Determining distribution of inhaled aerosols - in the respiratory tract, by introducing as aerosol, a fluorescent cpd

Method comprises introducing, by inhalation as an aerosol, a fluorescent substance (I), having a fluorescence colour in UV light different from that of the natural fluorescence of lung tissue. The samples of respiratory tract tissue are then examined for the intensity of their fluorescence. Esp. (I) is an ethidium (3,8-diamino-5-ethyl-6-phenyl-phenanthridinium) salt and the sample may be a prepd. histological section or a homogenate from (a part of) the respiratory tract. Used for testing the efficiency of (a) medicaments used e.g. to treat bronchospasms or (b) inhalation apparatus and nebulisers. The method is quick and simple.