Aerosols for systemic treatment.

Abstract

The development of a new group of drugs (polypeptides) have recently increased the interest of alternative administration to the enteral route because of its proteolytic activity and the catabolism of the “first-pass effect.” Aside from the “needle,” the administration in the respiratory tract via aerosol is the method with the best efficiency. But several problems prohibited its spreading: (1) the accuracy and the reproducibility of the inhaled dose (range ca. 1:4); (2) the small amount of inhaled drug in relation to the dose in the aerosol delivery system (range ca. 1%–10%); (3) the fear of allergic reactions of the respiratory system; (4) the variability of the drug transport into the systemic circulation. New approaches and data raise hopes in reducing the problems: (1) aerosol delivery systems with defined particle spectrum and storage systems; slow vital capacity inhaling maneuver; (2) delivery systems that nebulizes nearly the total amount of drug; (3) all studies with the inhalation application of insulin, heparin, ergotamin, ribavirin, aminoglycosides, and “cigarette smoke” do not reveal any relevant allergic reaction; (4) many studies were performed in the last 10 years on the influence of substances and especially of diseases on the transport of molecules through the respiratory tract. Only a few of them are relevant (exogen allergic alveolitis, active sarcoidosis, active smoking). Aerosols for systemic drug treatment seems to be a gained alternative to the “syringe.”