Hydroxypropyl methylcellulose (HPMC) is used as one of the largest pharmaceutical excipients at home and abroad. HPMC can be used as film forming agent, adhesive, sustained release agent, suspension agent, emulsifier, disintegrating agent, etc.

Pharmaceutical excipients are an important part of pharmaceutical preparations, and their role is to ensure that drugs are selectively transported to tissues in a certain way and procedure, so that drugs are released in the body at a certain speed and time. Therefore, the selection of suitable excipients is one of the key factors for the therapeutic effect of pharmaceutical preparations.

1 Properties of HPMC

HPMC has many characteristics that other excipients do not have. It has excellent water solubility in cold water. As long as it is added into cold water and stirred slightly, it can dissolve into a transparent solution. On the contrary, it is basically insoluble in hot water above 60E and can only dissolve. Is a non-ionic cellulose ether, its solution does not have ionic charge, and metal salts or ionic organic compounds, so as to ensure that HPMC does not react with other raw materials in the preparation production process. With strong anti-sensitivity, and with the increase of molecular structure of the degree of substitution, anti-sensitivity is also enhanced, using HPMC as adjuvant drugs, relative to the use of other traditional adjuvants (starch, dextrin, sugar powder) drugs, the quality of the effective period is more stable. It has metabolic inertia. As a pharmaceutical auxiliary material, it can not be metabolized or absorbed, so it does not provide calories in medicine and food. It has unique applicability for low calorific value, salt-free and non-allergenic medicine and food needed by diabetic people. HPMC is more stable to acid and alkali, but if it exceeds pH2~11 and is subjected to a higher temperature or storage time is longer, the viscosity will be reduced. Aqueous solution provides surface activity and presents moderate surface tension and interfacial tension values. It has effective emulsification in two-phase system and can be used as effective stabilizer and protective colloid. Aqueous solution has excellent film forming properties and is a good coating material for tablets and pills. The film formed by it is colorless and tough. Its plasticity can also be increased by adding glycerol.

2.Application of HPMC in tablet production

2.1 Improve dissolution

Using HPMC ethanol solution or aqueous solution as the wetting agent for granulation, for improving the dissolution of tablets, the effect is remarkable, and pressed into the film hardness is better, the appearance of smooth. Solubility of Renimodipine tablet: the solubility of adhesive was 17.34% and 28.84% when the adhesive was 40% ethanol, 5% polyvinylpyrrolidone (40%) ethanol solution, 1% sodium dodecyl sulfate (40%) ethanol solution, 3% HPMC dissolved into 10% starch pulp, 3% HPMC solution, 5% HPMC solution, respectively. 30.84%, 75.46%, 84.5%, 88%. Dissolution rate of piperic acid tablets: when the adhesive is 12% ethanol, 1% HPMC(40%) ethanol solution, 2% HPMC(40%) ethanol solution, 3% HPMC(40%) ethanol solution, dissolution rate is 80.94%, 86.23%, 90.45%, 99.88%, respectively. Dissolution rate of Cimetidine tablets: when the adhesive was 10% starch slurry and 3% HPMC(40%) ethanol solution, the dissolution rate was 76.2% and 97.54%, respectively.

From the above data, it can be seen that THE ethanol solution and aqueous solution of HPMC have the effect of improving the dissolution of drugs, which is mainly the result of the suspension and surface activity of HPMC, reducing the surface tension between the solution and solid drugs, increasing the moisture, which is conducive to the dissolution of drugs.

2.2 Improve the quality of coating

HPMC as a film forming material, compared with other film forming materials (acrylic resin, polyethylene pyrrolidone), the biggest advantage is its water solubility, do not need organic solvents, safe operation, convenient. And HPMC has a variety of viscosity specifications, appropriate selection, coating film quality, appearance is better than other materials. Ciprofloxacin hydrochloride tablets are white plain tablets with double-sided letterings. These pills for thin film coating is difficult, through the experiment, selects the viscosity of 50 mpa # s of water-soluble plasticizer, can reduce internal stress of thin film, coating tablet without bridge/sweat 0, 0, 0, 0 / orange peel/permeability oil, 0 / crack, such as quality problem, coating liquid film forming, good adhesion, and bring word edge without leakage, legible, One – sided bright, beautiful. Compared with traditional coating liquid, this prescription is simple and reasonable, and the cost is greatly reduced.