In vitro drug release profiles of pH-sensitive hydroxyethylacryl chitosan/sodium alginate hydrogels using paracetamol as a soluble model drug.

The aim of this study is to investigate in vitro drug release profiles of pH-sensitive hydrogels composed of hydroxyethylacryl chitosan (HC) and sodium alginate (SA). The hydrogels were crosslinked by dipping method using different ionic crosslinkers (e.g., Ca(2+), Zn(2+) and Cu(2+)). The crosslinking reaction was confirmed by FT-IR. Swelling behavior and stability of the hydrogels in simulated digestive media were investigated. The result indicated that the combination between HC and SA could delay the degradation time of the hydrogels. Calcium crosslinking system showed higher stability than that of zinc or copper crosslinking system. In vitro drug release profiles were studied using paracetamol as a soluble model drug. The amount of paracetamol release in simulated gastric fluid (SGF) was relatively low (<20%). In simulated intestinal fluid (SIF), the burst release of paracetamol was depressed with increasing HC content and/or applying crosslinker. The HC75SA25 formulation demonstrated the linearity of drug release profile. Additionally, the amount of drug release from the 0.5M calcium HC50SA50 hydrogel in SIF was lower than 20%. The comprehensive results of this study suggested their potential in the application of site-specific oral drug delivery in intestine and colon.