First theoretic analysis of magnetic drug targeting in the lung

Magnetic drug targeting in the bloodstream has been intensively studied recently, but also other interesting access and transport pathways fulfill the basic conditions for this method. More recently, magnetic drug targeting has even been accomplished for aerosol application in mouse models and indicated unmistakable advantages over all currently available therapies for lung tumors and any other very localized lung disease. In this paper, the application of magnetically labeled aerosols to the lung via the airways is theoretically highlighted for the first time in the literature. The fundamental difference compared to targeting via the bloodstream lies in the medium and the presence of the bronchial surface: When touching the epithelium of the lung outside the target region, a particle will deposit on the surface and not enter the air stream again. We are the first to compose a comprehensive physical description and provide a fundamental understanding of this potential expedient for treating cancer and other localized diseases. With our approach, we found optimal conditions for this sort of therapy. As a main parameter for optimization, the droplet size could be identified by minimizing unwanted deposition outside the target due to secondary effects, which compete with the magnetic forces. This may improve therapeutic efficiency and reduce side effects of otherwise not well-tolerated compounds, such as chemotherapeutics at the same time.