Synthesis and in vitro evaluation of acrylate-based macromolecular prodrugs containing mesalazine for colon-specific drug delivery

This work, describes synthesis and in vitro evaluation of new acrylic-type polymeric prodrugs containing mesalazine, as colon targeted drug delivery systems. First, mesalazine reacted with formic acid, and the obtained material was reacted with 2-hydroxypropyl methacrylat in the presence of 1,1-carbonyldiimidazole to produce methacryloyloxypropyl 5-amino salicylate. The resulted acrylic-derivative of mesalazine was then polymerized with various acrylic monomers by free radical solution polymerization, utlizing azobisisobutyronitrile as an initiator at 70±2°C. The obtained polymer-drug conjugates were characterized by FT-IR, 1H-NMR, elemental analysis, gel permeation chromatography, and differential scanning calorimetery techniques. The release studies were performed into dialysis bags by hydrolysis buffered solutions at 37°C. Detection of hydrolysis by UV spectrophotometer at free drug λmax (300 nm for pH 1; 339 nm for pH 7 and 8) in selected intervals showed that the mesalazine can be released by selective hydrolysis of the ester bond at the side of drug moiety. The release profiles indicated that the hydrophobicity of polymers and the pH value of the hydrolysis media have strongly effects on the hydrolytic behavior of the polymeric prodrugs.