Celecoxib-loaded injectable composite microspheres for anti-inflammatory therapy in osteoarthritis

Osteoarthritis is associated with a weakly acidic intra-articular microenvironment, which provides an intrinsic trigger for pH-responsive drug delivery systems to achieve site-specific and controlled drug release, thereby enhancing therapeutic efficacy. In this study, celecoxib (CXB)-loaded microspheres (CM-10) for intra-articular injection were fabricated using a microfluidic technique with poly(lactic-co-glycolic acid) (PLGA)/CaCO₃ as the carrier. The microspheres were systematically characterized in terms of morphology, encapsulation efficiency, and physicochemical properties. Their pH-responsive drug release and degradation behaviors were evaluated under different in vitro conditions, and the degradation behavior following intra-articular injection was further investigated. In addition, the pharmacodynamic effects of CM-10 were assessed in an osteoarthritis model. The results demonstrated that CM-10 exhibited pronounced pH-responsive release, with accelerated drug release under acidic conditions and sustained degradation following intra-articular administration. Furthermore, CM-10 effectively promoted articular cartilage repair and improved therapeutic outcomes. These findings indicate that CM-10 has promising potential as a pH-responsive intra-articular drug delivery system for osteoarthritis therapy.