(124g) Externally Triggered on-Demand Drug Delivery from Polymer Matrices Induced by a Magnetic Field

The pharmaceutical industry asks for prolonged and better control of drug administration to allow for more effective therapies. Highly potent drugs, e.g. as used in chemotherapy, require a certain amount of drug released in a specified time interval at a specific site in the human body. These potent drugs often have a very narrow therapeutic window, making it difficult to maintain an effective drug level for a prolonged time. A polymeric implant containing drugs can be used to create on-demand release by use of an external trigger. The focus of our work is to create a polymeric drug delivery system, which can be switched on and off by the use of a magnetic field, see enclosed figure.

By heating the implant from below to above its glass transition temperature, the diffusion coefficient of the drugs increases significantly. To induce drug release, superparamagnetic iron oxide nanoparticles have been imbedded in the implant, which can be heated by an alternating magnetic field (2850 A m^-1, 745 kHz). Superparamagnetic iron oxide nanoparticles have been synthesized by coprecipitation of ferric and ferrous chloride in aqueous solution as well as by a seed grow method in organic solvent. In addition, commercially available nanoparticles have been investigated with respect to the heating properties in magnetic fields applicable for medical treatment. These nanoparticles are embedded into biocompatible polyacrylates through solvent casting and extrusion methods. Subsequently, these cores have been coated with a polymer with an appropriate T_g, containing ibuprofen as a model drug. Results show sufficient heating of the polymer matrix by the magnetic field to exceed the glass transition temperature of the polymer within seconds. Subsequent release experiments show a clear on/off release behavior from the implant, triggered by the external magnetic field. The ratio between the on and off release appears to be in the order of 10,000.