The ascent of pulmonary drug delivery

The origins of inhalation therapy can be traced back to the early civilizat ions but this route of administration was relatively uncommon until recentl y. Direct delivery of drugs to the: lung by inhalation for the treatment of respiratory disease grew rapidly in the second half of the 20th century as a result of the availability of effective asthma drugs in convenient, port able delivery systems. In the search for non-invasive delivery of biologics , it was discovered that the large highly absorptive surface area of the lu ng could be used for systemic delivery of proteins such as insulin. New del ivery systems with efficiency and reproducibility to match the high cost an d therapeutic constraints of biologics are currently in late stage clinical trials. Even small molecular weight drugs previously administered by injec tion are tested via the inhalation route either to provide non-invasively r apid onset of action, or to improve the therapeutic ratio for drugs acting in the lung. Gene therapy of pulmonary disease is still in its infancy but could provide valuable solutions to currently unmet medical needs. The begi nning of the new millennium is therefore likely to witness development of m any valuable therapeutic products delivered by inhalation. (C) 2000 Wiley-L iss, Inc. and the American Pharmaceutical Association.