Understanding the fundamental chemical properties of pharmaceutical excipients is key to successful formulation design. Hydroxypropyl Methyl Cellulose Phthalate (HPMC-P) HP55 is a complex cellulose derivative whose specific structure dictates its functionality, particularly its role in enteric coating and as a tablet diluent. NINGBO INNO PHARMCHEM CO.,LTD. provides high-quality HPMC-P HP55 that meets stringent chemical specifications required by the pharmaceutical industry.

Chemically, HPMC-P HP55 is a phthalic acid ester of hydroxypropyl methylcellulose. The presence of the phthalate group is what confers its pH-dependent solubility. The cellulose backbone, modified with hydroxypropyl and methoxy groups, provides water solubility, while the esterified phthalate moiety introduces hydrophobicity and an acidic character. This balance is precisely what allows HPMC-P HP55 to function as an enteric coating agent. At low pH (acidic conditions), the phthalate groups are largely un-ionized, rendering the polymer insoluble. As the pH increases in the small intestine, the phthalate groups ionize, increasing hydrophilicity and causing the polymer to dissolve.

The key specifications for HPMC-P HP55 are critical for its performance. These typically include its dissolving pH, which for HP55 is generally established as starting to dissolve at pH 5.5. The labelled viscosity, often measured in cSt or mPa·s, is another important parameter, indicating the polymer's molecular weight and its impact on film strength and solution properties. For HPMC-P HP55, a common labelled viscosity is around 40 cSt. Furthermore, parameters such as water content (typically ≤5.0%), residue on ignition (≤0.2%), chloride and sulfate content (≤0.07%), and free phthalic acid content (≤1.0%) are rigorously controlled to ensure purity and compliance with pharmacopeial standards like USP, BP, and EP.

The phthalyl content is a crucial determinant of the dissolution pH. For HPMC-P HP55, the nominal phthalyl content is around 31%, which dictates its solubility profile. Variations in these specifications can significantly impact the performance of the enteric coating or the disintegrant properties of the HPMC-P.

NINGBO INNO PHARMCHEM CO.,LTD. ensures that its supply of Hydroxypropyl Methyl Cellulose Phthalate HP55 adheres to these critical chemical specifications. Our commitment to quality means that formulators can rely on our product for consistent performance in applications ranging from standard enteric coatings to more complex drug delivery systems like amorphous solid dispersions. By understanding and controlling these chemical properties, we help our clients achieve optimal results in their pharmaceutical preparations.