In this work, we have produced and characterised biodegradable microparticles for the local tratment of arthritis. Two active infredients were co-encapsulated: dexamethasone acetate, with anti-inflammatory effect, and superparamagnetic nanoparticles (SPION) to keep the whole system in place with an external magnetic field. The formulation has been optimised by an experimental design. Microparticles were physicochemically characterized and their interaction with synovial fibroblasts was studied, revealing that neither the microparticles nor their individual components were toxic for synoviocytes. Finally, the biological action of the microparticles was studied in a antigen-induced arthritis model in mice, with and without a subcutaneously implanted magnet near the mouse knee. Following intra-articular injection of dexamenthasone and SPION-containing microparticles in arthritic joints, a diminutaion int the synovial inflammation was observed 4 days afer the injection. This versatile type of microparticles could be used for the joint delivery of other drugs, such as p38 MAPK or IL-1 inhibitors.
