Supramolecular Hydrogel Dexamethasone-Diclofenac for the Treatment of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) severely affects patients' quality of life and is commonly treated with glucocorticosteroids injections, like dexamethasone, which may have side effects. This study aimed to create a novel low dose of twin-drug hydrogel containing dexamethasone and diclofenac and explore its potential as a drug delivery system for an enhanced anti-inflammatory effect. Its characterization involved rheology, transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Furthermore, the hydrogel demonstrated thixotropic properties. The hydrogel exhibited no cytotoxicity against RAW 264.7 macrophages. Furthermore, the hydrogel demonstrated a significant anti-inflammatory efficacy by effectively downregulating the levels of NO, TNF-α, and IL-6 in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. The co-delivery approach, when intra-articularly injected in adjuvant-induced arthritis (AIA) rats, significantly alleviated chronic inflammation leading to reduced synovitis, delayed bone erosion onset, and the downregulation of inflammatory cytokines. The biocompatibility and adverse effect evaluation indicated good biological safety. Furthermore, the hydrogel demonstrated efficacy in reducing NF-κB nuclear translocation in LPS-induced RAW 264.7 macrophages and inhibited p-NF-kB, COX-2, and iNOS expression both in RAW 264.7 macrophages and the joints of AIA rats. In conclusion, the findings indicate that the hydrogel possesses potent anti-inflammatory activity, which effectively addresses the limitations associated with free forms. It presents a promising therapeutic strategy for the management of RA.