In silico guided design and in vivo evaluation of Diacerein loaded SLNs embedded in situ gels for sustained intra-articular osteoarthritis therapy.

Abstract

Background: Osteoarthritis (OA) is a multifactorial joint disorder characterized by inflammation, oxidative stress, and progressive cartilage degeneration, for which conventional therapeutic agents remain limited by low bioavailability and systemic side effects.

Objectives: This study aims to integrate in silico guided and experimental nanoparticle-based drug formulations and in vivo analysis targeting the inflammatory genes, proteins, and oxidative markers in OA therapy.

Methods: In silico screening was conducted on ligands based on SwissSimilarity and led to the identification of TNF-α inhibitors. High binding affinity and stability of the complex were verified by Docking studies (AutoDock Vina) and molecular dynamics simulations (Desmond), 100 ns. THA was produced. SLNs with Diacerein (DC-SLNs) were prepared and entrapped into thermosensitive in situ gels (ISG) that were made of THA, poloxamer 407 and poloxamer 188. The formulations were assessed physically and in vitro release dynamics. The efficacy of in vivo drug formulation was determined by osteoarthritis rat model with knee diameter, oxidative and inflammatory markers.

Results: Swiss-similarity screening with Rhein as a reference ligand identified eight structurally similar compounds in the DrugBank database, including Diacerein, Rheinanthrone, Salsalate, and others, with high similarity scores (> 0.7); DC showed the strongest TNF-α binding (- 10.7 kJ/mol). The complex stability was proved by MD simulations (RMSD 2.6 A). In both gels, gelation was appropriate, injectability was excellent, and non-Fickian release occurred. Thermal studies, PXRD, and SEM showed lower crystallinity and a porous structure. Both formulations yielded significant reductions in joint swelling, pro-inflammatory cytokines (TNF-α, IL-6, NF-κB), improved antioxidant activity, and reduced inflammatory and oxidative mediators associated with cartilage degradation, while the DC-SLN@THA-ISG has better therapeutic efficacy than DC@THA-ISG.

Conclusion: In silico in vivo studies prove the efficacy of DC-SLN@THA-ISG as a biocompatible and sustained intra-articular formulation in managing osteoarthritis.