A novel pH sensitive N-succinyl chitosan/alginate hydrogel bead for nifedipine delivery

A novel N-succinyl chitosan(Suc-Chi)/alginate hydrogel bead was prepared by the ionic gelation method for the controlled delivery of nifedipine. The structure and surface morphology of the hydrogel were characterized by FTIR and SEM, respectively. Factors influencing the swelling ability of the hydrogel bead were also investigated, such as the ratio of Suc-Chi and alginate (X(1)), the weight ratio of drug to polymer (X(2)), the volume ratio of alginate/Suc-Chi to CaCl(2) (X(3)), crosslinking time (X(4)), CaCl(2) concentration (X(5)). In addition, the delivery behavior of nifedipine from the hydrogel bead was studied. The amount of nifedipine released from the hydrogel bead at pH 1.5 was relatively low (11.6%), while this value approached 76% at pH 7.4. The results clearly suggested that the Suc-Chi/alginate hydrogel bead may be a potential polymeric carrier for drug delivery in the intestinal tract. The release of nifedipine from the hydrogel bead at various pH values was analysed by a semi-empirical equation and it was found that the drug release mechanisms were either 'anomalous transport' or 'case-II transport'.