Magnetic Drug Delivery in Therapeutics

Magnetic modulated drug delivery system addresses the major problem of initial biodistribution of drug carrier. It involves the use of particulate carriers to a localized diseased site. Magnetic microspheres can be used for sitespecific drug targeting as in case of tumors, magnetic bioseparation and also can be used for non-targeted drug delivery as in case of contrast agents (MRI) and drug reservoirs that can be activated by a magnet of suitable strength applied outside the body. This delivery system has the distinct advantage of locally congregating high concentrations of the drug at the diseased site thereby minimizing drug requirement and side effects. Though it is expensive and requires high technical approach, it can be adapted to any part of the body. Various magnetic microspheres developed include magnetic nanoparticles, magnetically resealed erythrocytes and magnetic liposomes. Stereotaxis Inc. and FeRx Inc., are major commercial developers of magnetic guidance system for the medical industry. INTRODUCTION: In recent years, polymeric controlled drug delivery systems have evolved as one of the most attractive areas in drug delivery research. The drug release is controlled by the properties of the polymerdrug system. Despite having several advantages, one most important problem to this field is that all the systems so far developed, give release rates that are either constant or decrease with time. Patients suffering from Diabetes mellitus, arrhythmia or angina pectoris needs augmented delivery on demand, which can be achieved by the systems, which are associated with external or feedback control such as magnetic control. For Drug targeting, various carrier systems have been exploited like liposomes, nanospheres, microspheres, macromolecules etc. The difficulty of targeting drugs in vivo using these carrier systems is that the body contains 3 major tubes: the vascular, extracellular & intracellular compartments. Reticuloendothelial organs resist extravasations of drug carriers above 3-5 nm in molecular diameter. Other problems associated with in-vivo drug targeting i.e. the initial bio-distribution of drug carrier & bioengineering problems that must be addressed before the possibility of cell-receptor binding & cell uptake can be meaningfully explored. To overcome these problems, an alternative to these systems has been found i.e. to magnetize the carriers so that these particles can be retained at or guided to the target site by the application of an external magnetic field of appropriate strength.