Preparation and characterization of novel semi‐interpenetrating 2‐hydroxyethyl methacrylate‐g‐chitosan copolymeric microspheres for sustained release of indomethacin

A novel semi‐interpenetrating (semi‐IPN) graft copolymer of 2‐hydroxyethyl methacrylate (HEMA) with chitosan (CS) has been prepared in the form of microspheres, using water‐in‐oil (W/O) emulsion technique. Microspheres were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X‐ray diffractometry (X‐RD) to confirm the crosslinking and polymorphism of indomethacin (IDM). The X‐RD and DSC techniques indicated a molecular‐level dispersion of IDM in the IPN matrix. Scanning electron micrographs (SEM) taken at the cross section of the microspheres have shown rough surfaces around the microspheres. The sustained release characteristics of the matrices for IDM, an anti‐inflammatory drug, were investigated in pH 7.4 media. Particle size and size distribution of the microspheres were studied by laser light diffraction particle size analyzer. The drug was released in a sustained manner for up to 12 h.