pH-sensitive mesalazine carrier for colon-targeted drug delivery: A two-fold composition of mesalazine with a clay and alginate

The release of mesalazine, an anti-inflammatory drug for Crohn’s disease, should be deferred while delivering along the gastrointestinal tract to maximize drug absorption in the colon. To that end, we intercalated mesalazine into a clay mineral, montmorillonite (MMT), and we encapsulated the resulting composite inside a pHsensitive polymer, an alginate hydrogel bead. Once intercalated between the microscopic MMT layers, the mesalazine is prevented from dissolution during encapsulation into the alginate beads. As the resulting mesalazine-clay-alginate (MCA) bead is covered with a protective alginate layer, the mesalazine does not dissolve in acidic gastric conditions. In in vitro release tests, the MCA beads exhibited less than 5% mesalazine release in gastric solution, while ~20% was released over 7 h in the intestinal condition. Our results demonstrate that the MCA bead is a highly effective, biocompatible means of mesalazine delivery to the colon. [graphic not available: see fulltext]