HPMC uses in tablets coating

tablets coating is generally used in solid form preparation, according to the tablets coating materials can be divided into powder tablets coating, pellet tablets coating, particle tablets coating, tablet tablets coating, capsule tablets coating; According to tablets coating materials are divided into sugar tablets coating, half film tablets coating, film tablets coating (based on a wide variety of polymer materials, including enteric tablets coating), special material tablets coating (such as stearic acid, paraffin, polysaccharide); According to tablets coating technology, it can be divided into spray tablets coating, dip tablets coating, dry pressure tablets coating, electrostatic tablets coating and laminating tablets coating. Among them, spray tablets coating is the most widely used. Its principle is to spray tablets coating liquid into mist droplets covering the surface of materials (powder, particles, tablets). And quickly dry to form the tablets coating layer: according to the tablets coating purpose is divided into water soluble tablets coating, stomach soluble tablets coating, insoluble tablets coating, slow release tablets coating, enteric tablets coating.

The role of tablets coating includes: (1) moistureproof, light, air isolation to increase drug stability; (2) Cover up bad smell, reduce stimulation; (3) Improve the appearance, easy to identify; (4) Control the drug release site, such as in gastric juice easy to be destroyed so that it is released in the intestine: (5) control drug dispersion, release speed: (6) overcome incompatibility, etc. The tablets coating material should have the following requirements: non-toxic, no chemical inertia, stable in heat, light, water, air, and does not react with tablets coating drugs; (2) can be dissolved into evenly dispersed in the dispersion medium suitable for tablets coating: (3) can form a continuous, firm, smooth layer, crack resistance and has a good water isolation, moisture isolation, shading, air permeability; ④ Its solubility should meet the requirements of – fixed, sometimes need not be affected by PH, sometimes can only dissolve in a specific PH range. A kind of material that has above characteristic at the same time is not seen much, reason tends to use mixed tablets coating material more, in order to learn from each other.

Tablet tablets coating is the most widely used, it often uses pot tablets coating and buried pipe tablets coating (high efficiency tablets coating machine tablets coating), the latter is better for film tablets coating. Fluidized bed tablets coating is more suitable for materials with smaller particle size such as pellets and powder. Compared with sugar tablets coating, film tablets coating has many advantages 1)Shorten the time and reduce the material cost; (2) no significant increase in weight: (3) no need for the bottom layer: (4) strong, crushing and cracking resistance: (5) can be printed, also does not affect the chip lettering;(6) Can effectively protect the product from the influence of light, air and water; (7) No adverse effect on disintegration time 8) product aesthetic 9)provides an opportunity to use non-water tablets coating; Processes and materials can be standardized. Now the development of new product tablets coating preparation generally adopts film tablets coating, film tablets coating prescription basic composition includes film forming agent (tablets coating material), solvent, plasticizer, colorant, can also add pore-causing agent, insoluble filler, etc.. The composition of film tablets coating prescription is the key to the success of tablets coating. At present, water-soluble film tablets coating materials commonly used include hydroxypropyl methyl cellulose (HPMC) and hydroxypropyl cellulose (HPC). Polyethylene glycol (PEG), polyethylene pyrrolidone (PVP), enteric-soluble materials including enteric-soluble acrylic resin, hydroxypropyl methyl cellulose phthalate (HPMCP). Cellulose acetate phthalate ester (CAP). Shellac, insoluble materials include ethyl cellulose (EC), zein.

Over the years, film tablets coating has made remarkable progress. The traditional standard tablets coating system uses HPMC(hydroxypropyl methylcellulose) as the main polymer, which is still widely used today. HPMC-based tablets coating systems provide adequate performance, but there is still room for improvement. HPMC tablets coating film may not adhere to the tablet well, usually long tablets coating time, resulting in slow production. The subsequent introduction of PVA based tablets coating systems has further improved functionality, resulting in better tablets coating performance and faster production efficiency, which means that defects are less likely to occur in tablets.

As the viscosity of HPMC increases, the strength of the film formed by HPMC increases correspondingly, and finally reaches the maximum film strength no longer increases with the increase of the viscosity of HPMC.

In the tablets coating, in order to achieve the most efficient tablets coating, often improve the tablets coating liquid solid content, which will lead to the tablets coating liquid viscosity is too high, choose low viscosity HPMC can effectively solve this problem, but lead to the film strength is affected. To balance these twin problems, mixing polymers has become a common tool.

As the HPMC E15 content gradually increases, the viscosity of the mixture of HPMC E5 and HPMC E15 also gradually increases.

In sugar tablets coating, we have also gone from art to science. Sugar-coated products are aesthetically pleasing because they have a smooth, shiny, sweet finish that masks bitter tastes. But the biggest challenges in sugar tablets coating lie in productivity and reproducibility. Sugar tablets coating is a very laborious and time-consuming manual process and may vary from batch to batch depending on the person performing the tablets coating.