Hydroxypropyl methyl cellulose phthalate

Hydroxypropyl methyl cellulose phthalate (CAS 9050-31-1), commonly known as HPMCP, is a cellulose-based enteric polymer used in pharmaceutical manufacturing.

Where is Hydroxypropyl methyl cellulose phthalate used?

• Pharmaceutical tablets and capsules: primary enteric coating material where active ingredients must bypass the stomach
• Acid-sensitive APIs such as proton pump inhibitors and certain biologics: protection
• Solid dosage form development: film coating and hot-melt extrusion for delayed-release profiles
• Enteric matrix granules and multiparticulate systems: modified-release oral drug products
• It forms acid-resistant films that dissolve at defined pH thresholds in the intestinal tract.
• Sustained-release preparations, binders and microcapsule bases.
• Enteric coating material suitable for organic solvent system coating.

Good to know: Two primary grades, HP-50 and HP-55, are differentiated by pH dissolution thresholds of approximately 5.0 and 5.5. Its defined dissolution pH range makes it a specification-critical excipient in generic drug development.

Formulation notes

• Shows relatively many incompatibilities with plasticizers.

Typical specification

• Phthalyl content ranges from 27.0% to 35.0%.
• Water content is not more than 5.0%.
• Grade HP-45 dissolves at pH above 4.5.
• Below pH 4.5, it is insoluble regardless of the ratio of substituents.
• Labeled viscosity at 20°C is 170 cSt.

Regulatory status

• Product quality complies with USP-NF/EP/BP.
• Generally recognized as safe (GRAS) for use in foods and pharmaceuticals.

Frequently asked questions about Hydroxypropyl methyl cellulose phthalate

What are the limits for heavy metals and free phthalic acid?

Heavy metals are not more than 0.001%, and free phthalic acid is not more than 1.0%.

What are the typical particle size and available grade characteristics?

It is a powder with an average particle size of 400-600 μm; a grade is available with purity HP55 and viscosity 32-48 mPa.s.

How should the polymer be added to a mixed coating solvent?

With a mixed solvent such as ethanol/water or ethanol/dichloromethane, pour the ethanol into the vessel first, stir slowly, then add all of it to the ethanol to obtain a balanced solution, then slowly pour the other solvents into the mixture.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.