Synthesis and characterization of pH-sensitive hydrogel composed of carboxymethyl chitosan for colon targeted delivery of ornidazole.

In the present study, carboxymethyl chitosan was prepared from chitosan, crosslinked with glutaraldehyde and evaluated in vitro as a potential carrier for colon targeted drug delivery of ornidazole. Ornidazole was incorporated at the time of crosslinking of carboxymethyl chitosan. The chitosan was evaluated for its degree of deacetylation (DD) and average molecular weight; which were found to be 84.6% and 3.5×10(4) Da, respectively. The degree of substitution on prepared carboxymethyl chitosan was found to be 0.68. All hydrogel formulations showed more than 85% and 74% yield and drug loading, respectively. The swelling behaviour of prepared hydrogels checked in different pH values, 1.2, 6.8 and 7.4, indicated pH responsive swelling characteristic with very less swelling at pH 1.2 and quick swelling at pH 6.8 followed by linear swelling at pH 7.4 with slight increase. In vitro release profile was carried out at the same conditions as in swelling and drug release was found to be dependant on swelling of hydrogels and showed biphasic release pattern with non-fickian diffusion kinetics at higher pH. The carboxymethylation of chitosan, entrapment of drug and its interaction in prepared hydrogels were checked by FTIR, (1)H NMR, DSC and p-XRD studies, which confirmed formation of carboxymethyl chitosan from chitosan and absence of any significant chemical change in ornidazole after being entrapped in crosslinked hydrogel formulations. The surface morphology of formulation S6 checked before and after dissolution, revealed open channel like pores formation after dissolution.

Vaghani SS ，Patel MM ，Satish CS 《-》

Poly(ethylene glycol)-carboxymethyl chitosan-based pH-responsive hydrogels: photo-induced synthesis, characterization, swelling, and in vitro evaluation as potential drug carriers.

In this study, carboxymethyl chitosan was prepared, characterized, and then photo-induced graft copolymerized with poly(ethylene glycol) under a nitrogen atmosphere in aqueous solution using 2,2-dimethoxy-2-phenyl acetophenone (DMPA) as the photo-initiator. The grafting copolymerization process was confirmed and the resulting copolymers were characterized using differential scanning calorimetry (DSC), FTIR spectroscopy, 2D-X ray diffraction, and elemental analysis. The kinetics of the grafting reactions was also studied. Under the applied experimental conditions, the optimum grafting values were obtained at: CMCs=0.2 g, PEGA=249 mM, DMPA=10.4 mM at a 2 h reaction time. Some of the resulting copolymers were selected and used in the presence of methylene bisacrylamide (MBA) as a crosslinking agent to develop pH-responsive hydrogel matrices. The swelling characteristics and the in vitro release profiles of 5-fluorouracil (5-FU), as a model drug, from the hydrogels were investigated. The results revealed that the hydrogel matrices developed in this study can be customized to act as good candidates in drug delivery systems.

El-Sherbiny IM ，Smyth HD 《-》

pH-sensitive hydrogels based on semi-interpenetrating network (semi-IPN) of chitosan and polyvinyl pyrrolidone for clarithromycin release.

Vaghani SS ，Patel MM 《-》

Synthesis and characterization of carboxymethyl chitosan hydrogel: application as pH-sensitive delivery for nateglinide.

Vaghani SS ，Patel MM ，Satish CS ，Patel KM ，Jivani NP ... -  《-》

Novel complex hydrogels based on N-carboxyethyl chitosan and quaternized chitosan and their controlled in vitro protein release property.

Hu H ，Yu L ，Tan S ，Tu K ，Wang LQ ... -  《-》