What is the coating on tablet?

Tablet coating is solitary of the oldest pharmaceutical process still is endurance. Coating is a sequence by which an essentially dry, exterior layer of coating substance is practical to the external of an amount form in demand to confer definite reimbursement over uncoated diversity. It involves demand of a sugar or polymeric coat on the capsule. The recompense of tablet coating are odour mask, chemical defence flavour mask, physical and, protect the medicine in the abdomen, and to direct its let go profile. Coating may be practical to a widespread diversity of spoken solid amount form, such as element, tablet, crystals, granule, pellets and powder. When coating sonata is practical to a batch of tablets in a coating pan, the pill surface becomes covered with a tawdry polymeric film. There are numerous techniques for tablet coating such as enteric coating sugar coating, and film coating. The disadvantage of the older techniques of coating has been conquering with the recent progression in coating technologies. In this technology coating resources are in a straight line applied on the exterior of the tablet with no the use of any solvent. ICH guidelines also prefer the evading of organic solvents in pharmaceutical dosage formulations allowing for produce safety profile. This reconsider discuss the basic concept of tablet coating, the current advancement made, the difficulty faced throughout the development, their solution and coating assessment.


Tablet coating, tablets, Pills and candies with organic film can be described as a procedure of be relevant an edible paint on the surface of a pharmaceutical dosage form to achieve specific benefits. This is an additional process in tabulating which cause an increase in the cost of tablet manufacture. Coating can be functional to quite a few kinds of solid dosage forms like crystals, drug, pills, tablets, pellets, etc. When a coating solution is functional to a consignment of tablets in a coating pan, the surface of the remedy get covered with a tacky polymeric film. The tablets are then authorized to dry and the film ultimately forms a non-sticky dry exterior. The coating system involves parameters such as the nozzle spacing, drop size and spray pattern, (in adding together to numerous other non-spray interrelated parameter) which must all be accurately forced in order to make sure standardized allocation of the coating substance

Coating process

It is mostly attractive that the coating should be standardized and has to not crack less than stress. Consequently, a variety of technique was intended for the request of the coating on the tablet exterior. Normally, the tablet coating solution is sprayed onto the uncoated tablets as the tablets are being disturbed in a pan, fluid bed, etc. As the explanation is being functional, a thin film is produced which sticks to each tablet. The fluid division of the coating solution is then evaporating by transitory air over the exterior of the reducing pans. The coating may be shaped moreover by a single request or may be industrial in layers from side to side the use of numerous spraying cycles. Gyratory coating pans are frequently used in the pharmaceutical manufacturing.

Sugar coating / Sugar Film

Tablet coating urbanized in the beginning from the use of sugar to masquerade the taste and supply an attractive exterior to at the core. The method of tablet coating consists of quite a few steps, which are described below:


A seal coat is functional over the tablet to avoid dampness penetration into the tablet core. Shellac was before used as a sealant. But due to polymerization problems, it was substitute by zein (a corn protein derivative).

Sub coating

This step is complete to round the boundaries and enlarge the tablet mass.

Syrup Coating

The imperfection in tablet surface is enclosed up and the prearranged size is achieved. This step requires the utmost ability.


Give the capsule its final colour.


Powdered wax (beeswax or carnauba) is functional to provide a desired sheen.

Film coating

As the sugar coating procedure is very time strong and is needy on the skills of the coating operator, this system has been replace by film coating technology. The procedure involves spraying of a explanation of plasticizer, pigment and polymer, onto a gyratory tablet bed to form a thin, standardized film on the tablet exterior. The option of polymer mainly depends on the essential site of drug release x or on the necessary release rate.

Organic film coating

At present, the mainly frequent machinery for coating solid dosage forms is the liquid coating technology. In fluid coating, a mixture of polymers, pigments and recipients is dissolved in an organic solvent or water to form a solution, or dispersed in water to form a scattering, and then sprayed onto the quantity forms in a pan coater and dehydrated by incessantly as long as heat, characteristically by means of hot air, until a dry coating film is twisted. Organic solvent base coating provide a multiplicity of helpful polymer alternative, as mainly of the polymers are soluble in the extensive range of organic solvents. However, there are convinced disadvantage like they are combustible, toxic, and valuable and own environmental issues. ICH strategy also prefers the avoidance of organic solvents in pharmaceutical quantity formulations in view of products safety shape. So, Pharmaceutical industries are now paying much interest in early formulations with aqueous film coating.

Aqueous film finish / Aqueous Coating

All above nuisance with organic solvents resulted in change to use of irrigate as the preferred coating solvent. Aqueous-based coatings have been more and more used compare with organic base coatings. The exchange from organic solvent based coating to aqueous based coating makes the coating development more efficient, though originally it can need a little investment to improve the coating ability.

The necessitate of this up-gradation arise due to of advanced drying aptitude. This imply that one would necessitate 4 times more energy as compare to organic solvent