Prepation and Stability of Aqueous-Based Enteric Polymer Dispersions

Abstract
Aqueous, colloidal dispersions of the enteric polymers, cellulose acetate phthalate (CAP), hydroxypropyl methylcellulose phthalate (HP-551, and polyvinyl acetate phthalate (PVAP) have been developed; and their application in tablet film coating demonstrated. The formation of free phthalic acid as a result of phthalate ester hydrolysis was monitored during storage of the dispersions. Increased free phthalic acid concentrations were found to adversely affect physical stability in dispersions of the cellulose polymers. Storage temperature and pH effects on phthalate ester stability were also considered