DESIGNING A BIOCOMPATIBLE HYDROGEL FOR THE DELIVERY OF MESALAMINE

Mesalamine is being used extensively for long-term maintenance therapy of Crohn`s disease and colitis and may provide protection against the development of colorectal cancer. A new design for nanocomposite hydrogels based on cross-linked chitosan for the delivery of mesalamine is presented. To enhance drug loading in chitosan, the mineral montmorillonite was incorporated into the matrix. The exfoliated silica montmorillonite nanosheets form interactions with both chitosan and mesalamine, thus affecting the hydrogel’s drug release mechanism and swelling properties.

The impact of montmorillonite and glutaraldehyde concentrations on the hydrogel properties was investigated. In vitro drug-release studies detected slower release at short times when Montmorillonite was combined. This study is the first to evaluate the influence of pH during mixing and mixing duration. It was shown that lowering the pH during mixing delayed the release since the positively charged drug was better introduced between the Montmorillonite layers, as confirmed by Differential Scanning Calorimetry (DSC) and Fourier Transform Infra-red spectroscopy (FTIR) analysis. All hydrogels showed prolonged sustained release of mesalamine over 24 h in simulated colonic fluid (pH 7.4). When modeled, the mesalamine release profile suggests a complex release mechanism, involving adsorption of the drug to the montmorillonite and diffusion. The results imply that chitosan-montmorillonite hydrogels can serve as potential drug carriers for controlled-release applications.

Schematic illustration of interactions between chitosan, montmorillonite and mesalamine when cross-linked with glutaraldehyde