Effect of attapulgite contents on release behaviors of a pH sensitive carboxymethyl cellulose‐ g ‐poly(acrylic acid)/attapulgite/sodium alginate composite hydrogel bead containing diclofenac

A series of pH‐sensitive composite hydrogel beads, carboxymethyl cellulose‐ g ‐poly(acrylic acid)/attapulgite/sodium alginate (CMC‐ g ‐PAA/APT/SA), were prepared by combining CMC‐ g ‐PAA/APT composite and SA, using Ca 2+ as the ionic crosslinking agent and diclofenac sodium (DS) as the model drug. The effects of APT content and external pH on the swelling properties and release behaviors of DS from the composite hydrogel beads were investigated. The results showed that the composite hydrogel beads exhibited good pH‐sensitivity. Introducing 20% APT into CMC‐ g ‐PAA hydrogel could change the surface structure of the composite hydrogel beads, decrease the swelling ability, and relieve the burst release effect of DS. The drug cumulative release ratio of DS from the hydrogel beads in simulated gastric fluid was only 3.71% within 3 hour, but in simulated intestinal fluid about 50% for 3 hour, 85% for 12 hour, up to 90% after 24 hour. The obtained results indicated that the CMC‐ g ‐PAA/APT/SA hydrogel beads could be applied to the drug delivery system as drug carriers in the intestinal tract.