A pH-sensitive chitosan-tripolyphosphate hydrogel beads for controlled glipizide delivery.

A chitosan(CS)-tripolyphosphate (TPP) hydrogel bead was prepared by the ionic gelation method for the controlled delivery of glipizide. The structure and surface morphology of the beads were characterized by FT-IR and SEM, separately. Factors influencing the swelling behavior of the hydrogel beads were also investigated, such as CS concentration (X(1)), TPP concentration (X(2)), the weight ratio of drug to polymer (X(3)), crosslinking time (X(4)), and the volume ratio of CS to TPP (X(5)). In addition, the swelling property and the delivery behavior of the hydrogel bead was studied as well. With decreasing of pH value, the swelling ratio of the bead was increasing. The swelling ratio of hydrogel bead at pH 1.5 was relatively high, while this value was low at pH 6.8. The amount of glipizide released from the hydrogel bead at pH 1.5 was about 90%, while this value approached 36% at pH 6.8. The results clearly suggested that the CS-TPP hydrogel beads were used as a pH-sensitive controlled release system for the delivery of glipizide.