A Comprehensive Review on Tablet Coating

Research Article

Austin Pharmacol Pharm. 2016; 1(1): 1001.

A Comprehensive Review on Tablet Coating

Himaja V, Sai Koushik O*, Karthikeyan R and Srinivasa Babu P

Department of Pharmaceutics, Vignan Pharmacy College, India

*Corresponding author: Sai Koushik O, Department of Pharmaceutics, Vignan Pharmacy College, Vadlamudi-522213, AP, India

Received: July 07, 2016; Accepted: July 29, 2016; Published: August 01, 2016


Tablet coating is a not unusual pharmaceutical technique of applying a thin polymer-based film to a tablet or a granule containing Active Pharmaceutical Ingredients (APIs). Stable dosage paperwork are lined for some of reasons, the maximum crucial of that’s controlling the discharge profiles. The amount of coating at the surface of a tablet is vital to the effectiveness of the oral dosage shape. Capsules are typically coated in horizontal rotating pans with the coating answer sprayed onto the unfastened surface of the tablet mattress. The blessings of tablet coating are flavor covering, smell overlaying, bodily and chemical protection, protects the drug from the gastric surroundings and so on. There are various strategies for tablet coating which include sugar coating, film coating, and enteric coating. Latest trends in pharmaceutical technology are the development of coating techniques which overcomes the various risks associated with solvent based coatings. In those ultra-modern technologies coating substances are at once lined onto the surface of stable dosage bureaucracy without the use of any solvent. Numerous solvent less coatings are available inclusive of electrostatic dry coating, magnetically assisted impaction coating, compression coating, warm soften coating, powder coating, and supercritical fluid coating. Supercell Coating generation is a innovative tablet coating that appropriately deposits managed quantities of coating substances on capsules despite the fact that they may be extraordinarily hygroscopic or friable. Magnetically assisted impaction coating, electrostatic dry coating in solvent less coatings, aqueous film coating and Supercell coating technology also are available latest technique of coating. An ideal tablet ought to be free from any visual illness or functional defect. The improvements and innovations in tablet manufacture have now not reduced the issues, often encountered in the production, instead have accelerated the troubles, in particular due to the complexities of tablet presses; and/or the extra needs of high-quality. This review deal in detail approximately records, recent tablet coating technique and remedies associated with the tablet coating.

Keywords: Coating; History of coating; Supercell Coating; Magnetically Assisted Impaction Coating


Tablet is a pharmaceutical solid dosage form, comprising a mixture of active substances and excipients, commonly in powder form, pressed or compacted right into a stable. Capsules Dosage form is one of a most desired dosage form everywhere in the world. Almost all drug molecules may be formulated in a tablet and procedure of producing of drugs is very simple, and may be very bendy. Coating is a manner by using which a basically dry, outer layer of coating material is implemented to the surface of a dosage shape to achieve precise benefits. Coating may be implemented to a wide range of oral solid dosage shape, along with capsules, capsules, multi particulates and drug crystals [1-3]. While coating composition is carried out to a batch of capsules in a coating pan, the tablet surfaces grow to be protected with a tacky polymeric film. Before the tablet floor dries, the carried out coating adjustments from a sticky liquid to tacky semisolid and sooner or later to a non-sticky dry surface pans. Many stable pharmaceutical dosage forms are produced with coatings, both on the external surface of the tablet, or on substances dispensed inside gelatin tablets. The tablet ought to launch the medicament steadily and the drug should be to be had for digestion. The coating procedure can be in particular formulated to adjust how speedy the tablet dissolves and in which the lively tablets are to be absorbed into the body after ingestion. The complete coating system is conducted in a chain of routinely operated acorn-formed coating pans of galvanized iron stainless-steel or copper [4-6]. The smaller pans are used for experimental, developmental, and pilot plant operations, the larger pan for industrial production.

Basic percepts involved in tablet coating

Tablet coating is the application of coating composition to moving bed of tablets with concurrent use of heated air to facilitate evaporation of solvent.

a) Solution wherein affects the release pattern as little as feasible and does not markedly exchanges the advent.

b) Modified release with specific requirement and release mechanism tailored to frame characteristic within the digestive tract.

c) Modified release with particular requirement and release mechanism tailored to body characteristic in the digestive tract.

d) Insulation is being provided by the Color coating.

e) To include every other drug or components adjuvant in the coating to keep away from Chemical incompatibilities or to provide sequential drug release.

f) To enhance the pharmaceutical elegance by means of use of unique shades and contrasting printing.

Coating process, design & control

In maximum coating methods, the coating solutions are sprayed onto the capsules because the tablets are being agitated in a pan, fluid mattress, and so forth. As the solution is being sprayed, a thin film is formed that adheres directly to every tablet. The coating may be shaped with the aid of an unmatched application or can be constructed up in layers through the use of more than one spraying cycles. Rotating coating pans are regularly used within the pharmaceutical industry. Uncoated tablets are located inside the pan and the liquid coating answer is brought into the pan even as the tablets are tumbling. The liquid part of the coating answer is then evaporated by using passing air over the surface of the tumbling drugs. In assessment, a fluid bed coater operates via passing air through a bed of tablets at a velocity sufficient to assist and separate the drugs as person gadgets. As soon as separated, the drugs are sprayed with the coating composition. The coating method is normally such as the subsequent steps:

a. Batch identification and Recipe selection

b. Loading/Dispensing

c. Warming

d. Spraying

e. Drying

f. Cooling

g. Unloading

History of Coating Technique

“Panning” turned into the unique word for the manner of adding a coating to a tablet. The word panning remains a commonplace time period that’s used in the confectionary enterprise. In past years coating carries out essentially using a rotating drum on a stand. A coating answer turned into brought, while the rotation of the pan allotted the solution during the mattress of tablets. The primary drawback of this technology was gradual looking ahead to the coating technique to dry; and the trick turned into to get it to dry evenly. With the advent of movie coating a movie or skinny membrane, normally representing 1-3 % of the whole tablet weight, became sprayed on the use of a perforated pan. To lower the overall manner time, holes had been made through the pan in order that handled air warm or cold will be pulled via the pan, just like a garments dryer, permitting the tablets to dry speedier. With this advent of stepped forward drying came the potential to replace the movie coating solution from a solvent primarily based option to a water primarily based solution [7-10].

Traditional Coating Techniques

Generally three methods are used for tablet coating:

a) Sugar Coating

b) Film Coating

Sugar coating

Steps in sugar coating:

Film coating formulation (Composition of the coating liquid)

Polymer/Film Former: A film former capable of producing smooth thin films reproducible under the prescribed coating conditions.

Classified as

1. Non enteric materials

E.g. HPMC, MHEC, EC, HPC, Povidone, SCMC, PEG, Acrylate Polymers

2. Enteric materials

E.g. CAP, Acrylate Polymers, HPMCP, PVAP.

The above characteristics of film Coating are depicted in Table 2 & Table 3.