Exploring the Film Coating Process in Pharmaceutical Manufacturing
The tablet coating process is done to improve certain characteristics of the core tablet like improving the stability, enhancing the elegance, taste masking, and also to achieve controlled release. Film coating when compared to sugar coating can be done in less time and it’s not as tedious as sugar coating. Film coating is the deposition of a thin film of coating material on the tablet core.
Film coating involves
- Preparation of coating solution: The coating solution is prepared using a high-speed mixer and all the coating materials are added slowly in a sequential manner according to the formula and kept aside.
- Loading of tablets: The tablets are then loaded into the coating pan and are prewarmed before coating
- spraying of coating solution until desired weight gain: Tablets are coated by pumping the coating solution at the desired RPM and maintaining the set parameters of coating like inlet temperature, exhaust temperature, etc. till desired weight gain is achieved
- Drying: Then the coated tablets are dried as per specified time and allowed to cool.
- cooling
Ingredients of coating Solution: Polymers which act as the backbone of the film, plasticizers which enhance the flexibility and reduce the brittleness of the film, solvents like ethanol, water to dissolve the ingredients, colorants like titanium dioxide, dyes, lakes, etc and other additives like anti-taking agents like talc and surfactants
- Solvents – these are used to make the solution, and these include ethanol, water, acetone etc. . These solvents help in transferring the coating materials on to the tablet surface.
- Polymers – most commonly used for film coating are hydroxy propyl methylcellulose, ethyl cellulose, hydroxy propyl cellulose, povidone, sodium carboxy methyl cellulose etc. Polymers give good appearance and form film to protect the tablet core.
- Plasticizers like castor oil, polysorbates, propylene glycol, glycerin enhance the flexibility of the film
Film coating can be done using non enteric polymers and enteric polymers depending on the type of release required of the tablet formulation.