Tablet Coating Techniques: Concept and Recent Trends

Abstract

Tablet coating is a common pharmaceutical technique of applying a thin polymer-based film to a tablet or a granule containing active pharmaceutical ingredients (APIs). Solid dosage forms are coated for a number of reasons, the most important of which is controlling the release profiles. Tablets are usually coated in horizontal rotating pans with the coating solution sprayed onto the free surface of the tablet bed. There are various techniques for tablet coating such as sugar coating, film coating, and enteric coating. In these latest technologies coating materials are directly coated onto the surface of solid dosage forms without using any solvent. Magnetically assisted impaction coating, electrostatic dry coating in solventless coatings, aqueous film coating and Supercell coating technology are also available recent technique of coating. An ideal tablet should be free from any visual defect or functional defect. The advancements and innovations in tablet manufacture have not decreased the problems, often encountered in the production, instead have increased the problems, mainly because of the complexities of tablet presses; and/or the greater demands of quality. This review deal in detail about history, recent tablet coating technique and remedies associated with the tablet coating. Pharmaceutical solid dosage forms include tablets, pellets, pills, beads etc. Tablets are coated for many reason such as masking odour, taste, colour of the drug, providing physical and chemical protection to drug, protecting drug from the gastric environment. Coating is a process by which a layer of coating material is applied to the surface of a dosage form. The amount of coating on the surface of a tablet is critical to the effectiveness of the oral dosage form. Recent trends in tablet coating focuses on overcoming disadvantage of solvent based coating. This review concerns with the coating process, equipments involved, coated tablets evaluation and specialized coating techniques.