A Guide to Tablet Coating Process

- Friday, May 17, 2019

Tablet coating is one of the commonly used pharmaceutical processes. This coating process can be applied by coating. The method can apply a substantially dry outer coating material to the surface of the dosage form to impart a particular benefit to the uncoated variety. It involves applying a sugar or polymer coating to the tablet.

Coating is an important part of the tablet production process. How to do the coating work directly affects the quality of the coated tablets.

Tablet coating process

The auxiliary materials required for tablet coating are sucrose, talc, gelatin, and pigment. The amount of talc powder can reach more than 50% of the weight of the core.

There are six steps in general tablet coating:

1. In order to prevent the tablet core from being damaged due to the occurrence of rotten film during the rolling process of the sugar coating pan, thus the tablet quality affected, it is necessary to apply 2-3 layers of powder coating layer to increase core hardness and wear resistance.

2. The barrier layer prevents physical or chemical degradation of the active ingredient in the core by moisture attack.

3. The powder coating layer is rolled into a desired shape and size with 2% gelatin syrup and talc powder.

4. The sugar coating layer is a single syrup.

5. The colored layer uses colored syrup.

6. Finally, polish or wax is used to achieve a bright luster and prevent the ingress of humid air.

So what is a tablet coating machine and how does it work? The tablet coating machine is a machine for uniformly coating and polishing the formed chips for the pharmaceutical industry, and can also be used for the candy mechanism pills or coatings in the food industry. The coated tablet has a bright and shiny surface, and the surface of the powdered sugar crystallizes to form a complete consolidated coating, which can also prevent the tablet chip from oxidative deterioration, moisture or volatilization, and can cover the chip to take discomfort. The taste is easy to identify and aid in the dissolution of the human stomach and in the stomach.

Types of Table Coating Machines

There are several types of tablet coating machines available in the market, including:

  1. Pan Coating Machines: These are the most commonly used type of coating machines, consisting of a rotating pan and a spray system. Tablets are loaded into the pan, which rotates while the coating material is sprayed onto the tablets. Pan coating machines can be used for both aqueous and non-aqueous coatings.

  2. Fluidized Bed Coating Machines: These machines use a fluidized bed of particles to suspend the tablets, which are then coated with a spray system. The coating material is sprayed onto the tablets, which are kept in motion by the fluidized bed. Fluidized bed coating machines are commonly used for enteric coating and controlled-release coating.

  3. Drum Coating Machines: Drum coating machines consist of a rotating drum and a spray system, similar to pan coating machines. However, the drum has a cylindrical shape, and the tablets are loaded into the drum through a slot. The drum rotates, and the coating material is sprayed onto the tablets as they tumble inside.

  4. Perforated Coating Machines: Perforated coating machines are designed to coat tablets that are too fragile or prone to chipping. These machines use a perforated drum or basket to hold the tablets and a spray system to apply the coating material. The perforations in the drum or basket allow the coating material to reach the tablets without damaging them.

Working principle

In order to make the chip evenly coated on the surface layer as soon as possible, and to achieve the purpose of polishing, it is necessary to manually spray the syrup and the mixing part in the pot. The pot body is rotated clockwise, so that the sugar-coated pieces are tumbled in the pot, and the frictional grinding is performed by sliding, and finally the coating crystals can be evenly distributed on all the chips. At the same time, the hot air is passed into the pot to remove the surface moisture of the tablet, and finally a qualified sugar coating chip is obtained.

The device can ensure that the tablet forms an optimal flow curve in the pot at a stable line speed, so as to meet the process requirements of the thickness of the sugar coating layer being uniform, the color is bright with no pitting occurs.


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