Bacteria and pH-sensitive polysaccharide-polymer films for colon targeted delivery.

The colon provides drug delivery opportunities for colon-specific and systemic delivery of various therapeutic agents. Different strategies have been utilized in targeting drugs to the colon. Recently, integrated systems which incorporate dual mechanisms in colon targeted delivery have received a lot of attention. Of particular interest is bacteria-aided biomaterials and pH-sensitive polymeric film (BPSF) coating for colon targeted drug delivery. The major constituents of these films are polysaccharides and pH-sensitive polymers. The pH-sensitive polymer retards drug release in the stomach and small intestine, while the polysaccharide is digested by colonic enzymes. Digestion of the polysaccharides by bacterial glycosidic enzymes increases the pore density in the film to facilitate drug release. Generally, bacteria-aided biomaterials and pH-sensitive films can be applied to the delivery of most small organic molecules to the colon. The review encompasses the pharmaceutical design parameters such as film digestibility, swelling index and dry mass loss (that provide molecular mechanistic analysis of film permeability) as well as tensile strength, elastic modulus, and elongation at break (that describe the desirable mechanical properties of the films). A critical analysis of formulation, techniques for characterization of film properties and drug-release kinetics from these systems are emphasized.