There are so many pharmaceutical Machines in the world today. From Encapsulating machines to sealers and many more. However, we will be looking at the Tablet Coating Machine.
The mechanical device known as a tablet coating machine coats the surface of tablet dosage forms. It coats these dosages with an essentially dry, thin layer of coating material to give coated varieties some distinct advantages over uncoated ones.
However, this article focuses on how this machine works, its advantages, and its types. Keep reading.
What are Tablet Coating Machines?
These machines are a piece of machinery that use thin coating film to coat a tablet’s exterior. Below are some of the reasons industries use Tablet Coating Machines:
- To conceal the drug’s flavor, smell, and color.
- To give the medicine chemical and physical protection.
- To stop medications that are sensitive to humidity, light, or oxygen from decomposing.
- To reduce the disagreeable taste that some medications may have when they partially dissolve in the mouth’s liquids while being absorbed.
- To make the mouth’s surface smoother in order to increase the mouth’s capacity to swallow and taste.
- To offer consistency and visual attractiveness, a smooth surface, and a homogeneous dispersion of color.
- Involves adding tracer compounds in the coating material, to act as an anti-counterfeiting medium.
And so much more.
How does it Work?
Tablet coating machines operate according to fairly straightforward principles. The way tablet coating machines operate is by drizzling coating chemicals onto a bed of tablets that can move either horizontally or vertically. The solvents’ evaporation is facilitated by a contemporaneous flow of hot air.
Advantages
Regarding the three main varieties, the benefits of tablet coating machines will be described:
Typical coating pan
- When an atomizing device is utilized, it is possible to distribute coating solutions or suspensions more quickly and evenly.
- Spraying enables continuous application of solution for film coating while reducing the amount of time between solution applications for sugar coating that must dry.
- Both the coating of films and the production of sugar can use it.
- A baffled pan and diffuser (Pellegrini pan system), immersion tube systems, and immersion sword systems can all readily increase the drying efficiency of the normal coating significantly.
Systems of air or fluid suspension
- High coating efficiency is achieved by air suspension coaters’ capacity to suspend and coat tablets simultaneously.
- It provides a substitute for pan coating and is especially well-liked for multiparticulate systems.
- The two spray-atomization systems (low-pressure air atomized systems and high-pressure airless systems) produce consistent thin layers from finely divided spray.
Systems with perforations
- By design, perforated pans typically use energy more effectively.
- Shorter coating times are produced by the coating machine’s improved drying efficiency.
- In a Glatt coater, a variety of airflow arrangements are possible.
- It can be utilized in the production of both sugar and film coatings.
Types
To accommodate their coating processes, several businesses have created their own coating equipment. These three fundamental types provide the foundation for the various tablet coating machines that are currently on the market.
- Standard coating pan
- Pellegrini pan
- Immersion sword system
- Immersion tube system
- Perforated coating pan
- Accela-cota
- Hi-coater systems
- Driacoater
- Glatt coater
- Fluidized bed or air suspension coater
- High-pressure airless systems
- Low-pressure air atomized systems
1. Standard coating pan
A typical coating pan is a circular piece of metal that is positioned asymmetrically on a stand. A motor rotates the pan, which has a diameter of 8 to 60 inches (15 and 200 cm), around its horizontal axis.
Additionally, the batch of tablets placed into the pan also tumbles due to the pan’s circular movement. Multiple passes across the spray application zone are permitted as a result.
The rotating tablet bed is coated with a solution. Spraying in an atomized form is used to accomplish this. Instead of only injecting the solution as a liquid, this can result in a quicker and more equal distribution of the solution.
Furthermore, hot air is pumped into the pan through ducts and then expelled out the front of the pan. This is where it is subsequently released onto the tablet bed surface. Numerous changes were made to the hot air handling equipment of the typical coating pan’s design in order to significantly increase drying efficiency.
Typical examples of such modifications include the design of conventional coating pans with:
- an immersion sword system – Through a perforated metal sword device that is submerged in the tablet bed, the drying air is introduced.
- a baffled pan and diffuser (Pellegrini pan system) – This enables the equal dispersion of drying air throughout the tablet or pellet bed.
- an immersion tube system – The spray nozzle is integrated into the tube tip, which is submerged in the tablet bed and used to supply hot air.
2. The perforated pan systems
A perforated or partially perforated drum makes up a perforated coated pan. In a confined space, it is rotated on its horizontal axis. Through spraying nozzles positioned inside the drum, the coating solution is applied to the surface of the spinning bed of tablets.
Furthermore, as pharmaceutical companies shifted from organic solvent-based coatings to aqueous coatings, perforated pans gained popularity.
The change was a logical reaction to the volatile nature of organic solvents. Explosion-proof construction’s high expense was required in the 1980s to account for such instability. The adoption of the Clean Air Act and its revisions in the early 1990s.
Additionally, depending on the manufacturer, perforated coating pans come in a variety of patterns. However, the goal is to optimize the machine’s drying capacity. In order to reduce core penetration at high spray rates, this is done.
Furthermore, they can be fully automated for processes including film coating and sugar coating. Perforated coating pan illustrations include:
a. Accela-cota & Hi-coater systems
The drying air in this apparatus is channeled into the drum after passing through the tablet bed. Finally, the drum’s perforations allow it to be drained.
b. Driacoater
The hollow, perforated ribs on the inside perimeter of the drum in the Driacoater are where the drying air is introduced. The drying air travels up through the rib dip in the tablet bed as the coating pan rotates, fluidizing the tablet bed, and exhausting through the pan’s rear.
c. Glatt coater
Fully perforated drums are used in the Glatt coater (Glatt perforated coating pans) design. This combines the highest spray rates with the fastest process times.
In a Glatt coater, drying air can either be routed in the opposite direction up through the drum perforations for partial fluidization of the tablet bed. It can also be directed in the first direction from the inside of the drum through the tablet bed and out an exhaust duct.
There are numerous conceivable airflow configurations.
3. Fluidized bed or air suspension systems
Highly effective coating systems include fluidized-bed coating machinery and air suspension coaters. Tablets (or granules) suspended in a columnar chamber by a positive (warmed) airflow are sprayed with the coating solution.
However, the airflow is managed to allow more air to enter the column’s center. The center of the tablet rises as a result. The airflow causes the tablets in the center to rise and then fall outward and downward to the chamber wall.
The procedure is currently being constantly repeated from the column’s bottom. Furthermore, coating solutions are continuously applied from the spray nozzles located at the bottom of the chamber. They can also be sprayed onto the top of the cascading tablet bed by nozzles located in the upper region of the chamber.
Tablet cores that are friable and prone to chipping and edge abrasion may be difficult to coat. They may be difficult to coat even under the optimum conditions in the fluidized bed systems. This is owed to the relatively rough tablet-to-tablet impact and tablet chamber contact.
There are basically two types of spray-atomization systems used to apply finely divided spray-coating solutions or suspensions onto the tablets.
- High-pressure airless systems
- Low-pressure air atomized systems
Conclusion on Tablet Coating Machine
Now that we’ve seen the advantages and types of tablet coating machines, it is reasonable to say we might have understood their importance in Pharmacy.
However, you should know that tablet coating is a tedious and time-consuming process.
FAQs
See below;
What is the tablet coating spray rate?
The bed temperature and, thus, the rate of solvent evaporation is influenced by the rate at which the coating formulation is applied to the tablets.
Why do we use tablet coating? Why do we use tablet coating?
To alter the hue for branding or other purely cosmetic reasons.
Stability: safeguarding the active substance from the stomach’s acidic environment, light, and/or moisture.
To offer a pill that is simple to swallow without the bitter taste of numerous active components, taste and/or odor masking is used.
What does tablet coating dew point mean?
The temperature range of the conditioned air used for tablet coating is normally between 50°C and 90°C. With an ambient temperature of 80°C and a dew point of 10°C, a hypothetical process would require a relative humidity (RH) of less than 2%.