Development and Characterization of Azathioprine-Loaded Chitosan Microspheres for Sustained Release

Abstract

Osteoarthritis (OA) is a chronic, progressive joint disease characterized by pain, stiffness, and reduced joint function. Conventional oral therapy often requires repeated administration due to poor bioavailability and short biological half-life, which results in adverse effects and low patient adherence. Azathioprine (AZA), an immunosuppressant, has demonstrated anti-inflammatory and disease-modifying potential in OA management. However, its therapeutic use is limited by low systemic absorption and rapid clearance.Polymeric microspheres offer an effective approach for controlled drug delivery by extending drug release and enhancing therapeutic outcomes. Chitosan, a natural biocompatible polymer with slow biodegradability, is highly suitable for sustained-release systems.The present study aimed to formulate and evaluate AZA-loaded chitosan microspheres for targeted and prolonged drug delivery. Microspheres were prepared using the emulsification heat-denaturation technique and assessed for preformulation parameters, drug-polymer compatibility, zeta potential, and in vitro release studies. UV spectrophotometric analysis confirmed λmax at 276 nm and the calibration curve showed good linearity. FTIR compatibility studies revealed no significant interaction between AZA and chitosan. In vitro release studies indicated sustained drug release over an extended duration following diffusion-controlled kinetics.