The present invention includes acidifying film coating compositions containing a polymer and an acidic component for use on orally-ingestible substrates such as tablets and the like. The acidifying coating compositions can be applied as an aqueous dispersion to an enteric-coated substrate to increase the disintegration resistance to aqueous media of up to pH 5.0. In preferred aspects, the acidic component is citric acid, lactic acid, stearic acid or mixtures thereof. Methods of preparing the dry film coatings, methods of preparing corresponding aqueous dispersions, methods of applying the coatings to substrates and the coated substrates themselves are also disclosed.