OMNICOATTM HPMCP
Cellulose derivative for enteric coating
Hydroxypropyl methyl cellulose phthalate has proved its value in enteric coating using organic solvent. The chemical structure of HPMCP is a monophthalic acid ester of hypromellose.
White or off-white powder or granule, odorless, tasteless. Practically insoluble in water, soluble in a mixture of equal volumes of acetone and methanol and in a mixture of equal volumes of methanol and methylene chloride. Practically insoluble in anhydrous ethanol.
The chemical structure is a Monophthalic acid ester of Hypromellose dissolving easily in different organic solvents into a clear solution whereas the most recommended solvents to be used are ethanol/water or isopropanol/water combinations. The enteric coating solutions can be applied on tablets, capsules or pellets.
General Product Information
HPMCP as enteric coating agent is insoluble in acidic environment like in gastric juice but dissolves immediately after the transfer of enteric coated tablets to the small intestine. It is prepared from highly purified pulp, a widely distributed natural material.
pH dependent disintegration of HPMCP
The threshold pH value for rapid disintegration of hypromellose phthalate can be controlled by varying the phtalyl content on the hypromellose backbone. HPMCP contains a carboxyl (phtalyl) group but its backbone structure is a water-soluble polymer. The phthalyl group defines the soluble nature of HPMCP, which is insoluble in water due to its hydrophobicity and soluble in weak acid to neutral medium.
Two types of HPMCP with different pH-solubilities, HP- 55 and HP-50, are available. HP-50 disintegrates at pH 5.0 and HP-55 at pH 5.5 respectively. Moreover, HP-55S, a special type of HP-55, was introduced which is distinguished by:
An appropriate grade of HPMCP for particular purposes should be selected application-specific.
|
PRODUCT NAME |
COMPENDIAL NAME |
GRADE |
DISSOLVING pH |
TYPICAL APPLICATION |
|
HPMCP |
Hypromellose Phthalate |
HP-55 |
≥ 5,5 |
Regular grade |
|
HP-55S |
Greater film strength |
|||
|
HP-50 |
≥ 5,0 | Soluble at lower pH |
Higher molecular weight
Greater film strength
Higher acid resistance properties.
