Treatment of systemic diseases by inhalation of biomolecule aerosols

Clinical experience since many years has shown that aerosol inhalation is an established route for the treatment of pulmonary diseases. In contrast, treatment of systemic diseases by means of aerosol inhalation is a novel therapeutic approach. This was caused for a long time by a lack of accuracy, efficiency, and reproducibility of the administered drug doses due to a poor knowledge of the physiological background of aerosol inhalation, an insufficient inhaler technology as well as a suboptimal breathing procedure. However, these problems have been solved in the last years and nowadays modern aerosol delivery systems allow the production of an aerosol with a defined and optimised particle size combined with an optimized breathing maneuver and optimization of the efficacy of the technology. Clinical studies demonstrated that only a small number of morphological factors (e.g., exogen allergic alveolitis, active sarcoidosis, active smoking) influence alveolar drug deposition and the inhaled systematically active compounds caused no relevant allergic reactions even after inhalation for longer time periods. Up to now, most data are available for the inhalation of insulin which has been introduced in clinical treatment for a short time. However, a lot of other molecules have been tested in aerosol inhalation studies. This review describes some examples other than insulin in the field of inhalant treatment of systemic diseases.