کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5820669 | 1557399 | 2012 | 8 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: pH sensitive polyelectrolyte complex of O-carboxymethyl chitosan and poly (acrylic acid) cross-linked with calcium for sustained delivery of acid susceptible drugs pH sensitive polyelectrolyte complex of O-carboxymethyl chitosan and poly (acrylic acid) cross-linked with calcium for sustained delivery of acid susceptible drugs](/preview/png/5820669.png)
The present study investigates the ability of a polyelectrolyte complex, composed of O-carboxymethyl chitosan (O-CMC) and carbopol cross linked with calcium, as a pH-sensitive carrier for acid susceptible drugs. DSC studies were performed to confirm the formation of O-CMC-carbopol complex. Double endothermic peaks in thermogram of polyelectrolyte beads reflect the molecular changes brought in after cross-linking. FT-IR spectroscopy was used to reveal peak variation of the carboxylic groups as a function of pH 1.2 and pH 6.8. The formation of polyelectrolyte complex, on account of electrostatic interactions between the COOâ group of carbopol and the NH3+ group of O-CMC, was also confirmed by FT-IR studies. Swelling of the O-CMC-carbopol film showed a pH-dependent profile that was affected by calcium ion concentration. The swelling rate was more significant at intestinal pH because the ionization of carboxylic acid group on O-CMC and carbopol creates electrostatic repulsion. Release behavior of drug is relative to the viscosity of solution and the ionic interaction between O-CMC and carbopol. Mucous glycoprotein assay revealed that ionization of carboxylic group on the beads at intestinal pH formed a strong hydrogen bond with mucin, which was responsible for the prominent mucoadhesive property thus prolonging the intestinal residence time.
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Journal: International Journal of Pharmaceutics - Volume 436, Issues 1â2, 15 October 2012, Pages 418-425