Hydroxypropyl methyl cellulose (HPMC) or hypromellose, is a cellulose-based polymer for film coating, wet granulation, and hard capsule manufacturing. It is practically insoluble in hot water, acetone, anhydrous ethanol, and dissolves in cold water, resulting in a colloidal solution.1 . Resistance to salting : Hydroxypropyl methyl cellulose (HPMC) is a nonionic cellulose ether and it is not a polyelectrolyte . The aqueous solution of Hydroxypropyl methyl cellulose (HPMC) is comparatively stable even in the presence of metal salts or organic electrolytes . However, when the concentration of electrolytes exceeds a certain limit, gelation and precipitation may result .

2 . Surface activity : An aqueous solution of Hydroxypropyl methyl cellulose (HPMC) has a high surface activity and functions as a protective colloid agent , emulsion stabilizer and dispersant .

3 . Thermal gelation :An aqueous solution of Hydroxypropyl methyl cellulose (HPMC) will gel or precipitate when heated to a certain temperature , but it reverts to the original solution state on subsequent cooling . The temperature at which gelation or precipitation occur depends on the type of HPMC , its concentration and the rate of heating .

4 . pH stability :The viscosity of an aqueous solution of HPMC is hardly affected by acid or alkali , and the product can develop an original viscosity in the range of 3 . 0~11 . 0 . Therefore , the solution viscosity tends to keep stable during prolonged storage .

5. Water retention :Hydroxypropyl methyl cellulose (HPMC) is a high effective water retention agent . Its pharmaceutical grade product can be widely used in food, cosmetics and many other fields .

6 . Film forming :Hydroxypropyl methyl cellulose (HPMC) provides a strong , flexible and transparent film having a good barrier property against oil and grease .In food application , this property is often utilized for water retention and oil adsorption .

7 . Cohesiveness (Binding property) : Hydroxypropyl methyl cellulose (HPMC) , as a high performance binder, can also be used for molding food and medicine .

Hydroxypropyl methyl cellulose (HPMC) is used as adhesive, solutizer in tablet, film-forming reagents in pharmaceutical coating,delayed-release and controlled-release tablets or capsules, thickener and water-binding agent in liquid formulation, component in eye drop.