Fabrication of radiation cross-linked diclofenac sodium loaded carboxymethyl sago pulp/chitosan hydrogel for enteric and sustained drug delivery

Carboxymethyl sago pulp (CMSP) with a degree of substitution 0.8 was synthesised from sago waste and crosslinked with chitosan to form a hydrogel by electron beam (EB) irradiation. Diclofenac sodium was loaded into 40% CMSP/3% chitosan solution mixture and irradiated at 25 kGy. The hydrogel exhibited pH and temperature-sensitive swelling behaviour. Fourier-transform infrared spectroscopy, field emission scanning electron microscope, X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis were performed to characterise its properties. Drug entrapment efficiency of diclofenac sodium-loaded hydrogel was 65.4 +/- 0.2%. The release of diclofenac sodium from CMSP/chitosan hydrogel disc was low in an acidic environment (pH 1.2) and there was slow and sustained release in colonic pH (pH 6.8) over 32 h in a first-order manner. Based on the results of the disk diffusion test, the hydrogel exhibited antimicrobial activity against the tested microorganisms. Among tested formulations, 40% CMSP/3% chitosan hydrogel was shown to be the potential drug carrier for sustained drug delivery.