Drug delivery method and inhalation device therefor

A drug delivery device for administering a drug contained in an aerosol to a breathing passage of a patient for absorption on the mucous tissue of the patient which comprises

• (a) a collapsible airbag of fixed maximum dimensions which is impervious to passage of air except for an airbag opening;
• (b) a piece having one end adapted for communication with the breathing passage and connected by a bidirectional channel through said piece to the opposite end thereof to said airbag opening, said piece having a drug introduction opening for the introduction of an aerosol spray containing a predetermined amount of a drug, said drug introduction opening disposed such that said aerosol spray is introduced directly into said airbag through said piece and said airbag opening, in a direction away from said one end;
• and
• (c) signal means in said bidirectional channel to indicate when the rate of inhalation of said aerosol spray from said airbag exceeds a desirable limit, whereby the patient taking said drug is reminded to decrease the rate of collapse of said airbag, thereby maximizing drug utilization;
• said drug delivery device admitting a drug-containing aerosol through said drug introduction opening while said collapsible airbag is at least partially expanded, said drug being introduced into said the breathing passage with the contraction of said collapsible airbag through inhalation by said patient.