Enzyme and PH responsive 5-flurouracil (5-FU) loaded hydrogels based on olsalazine derivatives for colon-specific drug delivery

Colon-specific drug delivery systems are efficient for increasing the availability of drugs at colon region and are desirable for the treatment of local diseases such as ulcerative colitis and colonic cancer. We synthesized an acryloyl chloride modified olsalazine (olsalazine-AC) as an azo crosslinker which was copolymerized with hydroxyethyl methacrylate (HEMA) and methacrylic acid (MAA), and developed two types of azo hydrogels which contained single network hydrogel and interpenetrating network hydrogel as an enzyme responsive and pH responsive controlled release carrier for colon-specific drug delivery. The structure of the azo crosslinker was characterized by FT-IR and H-1 NMR spectra and the azo hydrogels were analyzed by using ultraviolet spectrophotometer and scanning electron microscopy. The in vitro release of the 5-flurouracil (5-FU) loaded azo hydrogels was carried out in PBS (pH 7.4), PBS (pH 2.0) and rat colonic fluid (RCF). The drug release profile revealed that 5-FU loaded in azo hydrogels released faster in rat colonic fluid. The results showed that these azo hydrogels could be potential drug carrier for colon-targeted delivery.