Studies on the physical properties of mixed pectin/ethylcellulose films intended for colonic drug delivery

The mechanical and permeability properties of mixed ethylcellulose/pectin films cast from dibutyl sebacate (DBS) plasticised aqueous dispersions of Aquacoat® and Pectin USP have been investigated. The films were subjected to tensile testing and the tensile strength (σ), work of failure, elongation at break, elastic modulus (E) and the σ/E ratio have been determined. Increasing concentrations of pectin imparted increasing brittleness and decreasing toughness to the films. Despite the inclusion of increasing quantities of the hydrophilic pectin into the films, the permeability to moisture remained essentially the same. The results imply that there is a limit to the amount of pectin that can be included in the coating material to still produce a satisfactory film, but the protective nature of the ethylcellulose to moisture is not compromised.