Carbon dioxide enhancement of inhalation therapy

A method of increasing the deposition of a drug into the respiratory tract of an individual or animal during inhalation therapy, comprising the steps of:

• mixing carbon dioxide gas with air to form a carbon dioxide-air mixture, said carbon dioxide-air mixture containing about 7.5% to about 10% by volume carbon dioxide gas;
• aerosolizing said drug in said carbon dioxide-air mixture wherein prior to aerosolization said drug is a soluble drug dissolved in a buffered solution or water or, in the alternative, said drug is an insoluble or lipophilic drug carried by a liposome, a sterically stabilized liposome, a slow release polymer or a polycationic polymer;
• and
• administering said aerosolized drug during inhalation therapy by continuously flowing said carbon-dioxide-air mixture wherein carbon dioxide in said mixture increases inhalation rate and inhaled volume of said aerosolized drug thereby increasing deposition of said aerosolized drug into the respiratory tract.