Synthesis, characterizations, in vitro and in vivo evaluation of Etoricoxib-loaded Poly (Caprolactone) microparticles--a potential Intra-articular drug delivery system for the treatment of Osteoarthritis.

Intra-articular Drug delivery systems (IA-DDS) deliver the drug directly to the diseased joint space with significantly lowered systemic toxicities. In this work, we explored Etoricoxib (COX-2 inhibitor)-loaded Poly caprolactone (PCL) microparticles (MPs) as a potential IA-DDS. MPs were prepared by Oil/Water (O/W) emulsion-solvent evaporation method. Formulation parameters like polymer to drug ratio, stabilizer concentration were optimized to get the maximum encapsulation efficiency. The prepared particles were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction studies (XRD), and Differential Scanning Calorimetry (DSC). The particles were found to be spherical and smooth-surfaced using SEM. FTIR studies proved that there was no chemical interaction between the drug and the polymer. XRD and DSC studies confirmed that Etoricoxib existed in its amorphous form while PCL had retained its semi-crystalline phase during the micro-encapsulation process. In vitro drug release studies proved that there was controlled release of the drug from the MPs for nearly 28 days. In vivo synovial drug clearance studies on SD rats proved that drug leach out rate from the joint region to the systemic circulation was slow which indicated that MPs had a good drug retention capacity. In vivo fluorescence imaging results confirmed that MPs could stay longer in the joint region for almost a month. Thus, PCL microparticles could be a potential IA-DDS for the treatment of the diseased joint regions especially for Osteoarthritis.