COMPARATIVE-EVALUATION OF AMMONIATED AQUEOUS AND ORGANIC-SOLVENT-BASED CELLULOSE ESTER ENTERIC COATING SYSTEMS - A STUDY ON FREE FILMS

The permeability and mechanical properties of ammoniated aqueous and o rganic-solvent-based enteric films were evaluated with free films and with the films applied to tablets. The enteric coating materials studi ed were cellulose acetate phthalate (CAP), cellulose acetate trimellit ate (CAT) and hydroxypropyl methylcellulose phthalate (HPMCP, HP-50) p lasticized with triacetin. Enteric films prepared from organic-solvent -based solutions showed lower permeability to basic drug (caffeine) an d hydronium ions, and the permeability decreased in the sequence CAT, HP-50, CAP. As regards mechanical and stress-strain properties, ammoni ated aqueous enteric films appeared to be somewhat weaker and more bri ttle than corresponding films prepared from acetone-based solutions. T he results suggest very acceptable resistance of organic-solvent-based enteric films against short-term storage under tropical conditions.