Synthesis, characterization and controlled release characteristics of PEGylated hydrogels for diclofenac sodium

Abstract

In this study, hydrogels of acrylamide with polyethylene glycol methyl ether (poly(AAm-co-PEG)) have been prepared by using acrylamide, maleated PEG (MPEG), hydroxyethyl methacrylate (HEMA) and N,N'-methylenebisacrylamide (MBAAm) by redox polymerization in aqueous media. The effect of AAm/MPEG mol ratio, HEMA and MBAAm concentrations on hydrogel swelling has been investigated in water. The co-polymers formed and MPEG were characterized by Fourier transform infrared spectroscopy (FT-IR). Swelling of the hydrogel matrices was evaluated gravimetrically. The method adopted was simple and viable to prepare hydrogels of AAm/PEG to encapsulate diclofenac sodium (DS), an anti-inflammatory drug, without the use of tedious routes like emulsification in oil phase, spray drying, etc. X-ray diffraction (XRD) spectra and scanning electron micrographs (SEM) of the DS-loaded hydrogels have shown the amorphous nature. Microgels of this study were irregular in shape with the average particle size ranging between 157 and 265 μm, as measured by laser light scattering. Drug entrapment efficiency of up to 99% was achieved. In vitro release studies have been performed in phosphate buffer (pH 7.4). The release of DS through hydrogel matrices was completed in about 10 h. Swelling data performed in water have been analyzed by using an empirical equation to investigate diffusion mechanism.