HPMCP (Hypromellose Phthalate)
Since its introduction into the market in 1971 as an enteric coating, HPMCP (hypromellose phthalate) has been demonstrated to be effective by many researchers. It is widely used by the pharmaceutical industry. HPMCP has been admitted into the NF, EP and JP.
It dissolves at pH 5-5.5 and this property can be controlled by varying the phthalyl content. Two grades of different pH solubility, HP-55 and HP-50, are available. The grade of HPMCP appropriate for a particular purpose should be selected in accordance with its properties and formulations.

Note: * 10 wt.% in a mixture of equal weights of Methanol and Methylene Chloride according to the USP/NF measuring method.