 Enteric coatings based on CAP are resistant to acidic gastric fluids, but easily soluble in mildly basic medium of the intestine.The pH sensitive solubility of CAP is mainly determined (as other properties of this mixed ester) by the degree of substitution (DS), namely the average number of substituent groups bound to an anhydroglucose unit (AGU), as well as by the molar ratio (acetyl and phthaloyl groups).These two structural characteristics of the polymer are dependent on the method employed for its synthesis.