HPMCP (Hypromellose Phthalate)
"HPMCP" (hydroxypropyl methylcellulose phthalate), since its production start into the market in 1971 as an enteric coating, has been demonstrated to be effective by many researchers. It is widely used as an enteric coating agent by the pharmaceutical industry. "HPMCP" had been admitted into the NF, EP and JP.
It can dissolve at pH 5-5.5 and be controlled by varying the phthalyl content. Two types of different pH solubility, HP-55 and HP-50, are available. A suitable grade of "HPMCP" for a particular purpose should be selected in accordance with the properties and formulations.

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