A comparative release study of curcumin and diclofenac sodium from genipin cross-linked composite hydrogel

A composite hydrogel, using chitosan and gelatin was formulated. Chitosan-gelatin hydrogel in ratio 0.5:1 was prepared in lactic acid (2%). The poor mechanical strength of the gel was overcome by crosslinking with 1% (w/v) genipin solution. The properties of composite hydrogel were tested based on the characterizations performed. Swelling test was performed by immersing cross-linked hydrogels in water for 20 hours and swelling indices were calculated. Infrared (IR) spectroscopy was done to ensure presence of crosslinking. In-vitro release of uncross-linked and crosslinked hydrogels were performed and subsequently, release kinetics of two drugs: curcumin (weak base) and diclofenac sodium (weak acid) were studied. Cumulative release was carried out in deionized water for 30 hours for both the drugs and was analyzed spectrophotometrically at 265nm for curcumin and 276nm for diclofenac sodium. Cross-linked hydrogel showed swelling of 99.28±0.04% for 20 hours. Release profile of curcumin loaded cross-linked hydrogel showed sustained release of about 80.04±0.54% over 30 hours; found best fit with Higuchi model following anomalous transport (n=0.90), while diclofenac sodium loaded cross-linked gel exhibited sustained release of about 71.72±0.04 % over 30 hours; found best fit with Higuchi model following Fickian diffusion (n=0.45). Overall, the results indicated that the cross-linked composite hydrogel could be tuned as a carrier for the transport of both acidic and basic biomolecules.