The pharmaceutical and nutritional supplement industries widely use continuous production coaters. These systems resolved many of the issues present in other coating techniques such as coating uniformity variation across batches and reducing the handling or changeover time.
Continuous Tablet Coating Stands on the Shoulders of Past Advancements in the Industry
In the past, tablets for pharmaceutical applications were all typically processed in batch equipment. Batch processing saves time and is a cost-effective use of your production line’s time. The batch production process made sense nearly a hundred years ago, and it still does today in some applications. However, over time, the processing equipment and techniques have seen multiple advancements.
Originally, the coating process was performed in solid coating pans. Then, manufacturers introduced side-vented perforated coating drums. This alteration allowed for more solution or film coating to evaporate in less time. That one change made coating times drop and process throughputs skyrocket across the industry.
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Those perforated coating drums still had their limitations. Large drum batches come with their own challenges. As the drum load climbs higher, the time and effort to load and unload them increases as well. You can also typically see the coating uniformity drop as the batch size increases. In a large coating drum, each individual tablet spends less time in the spray zone.
The difference in coating between tablets grows throughout production. In the largest batch coaters on the market, the tablet beds can run as deep as 500 mm. This bed depth can result in the tablets at the bottom becoming damaged under the considerable weight. A continuous production and process system addresses these problems. It offers a solution that gives the end user the best of both worlds: rapid production times and highly uniform product quality.
Continuous Processing System
Continuous tablet coaters provide a higher throughput alternative to the batch coater by minimizing the time spent in material handling and changeover between batches. They also use a smaller-diameter drum, which results in a measurably more uniform tablet coating and less damage to the integrity of the individual tablet itself.
Thomas Processing, along with a major manufacturer of over-the-counter medications, developed the continuous coating technology in 1992 and 1993. Before that, continuous manufacturing did exist, but it was applied to agricultural seeds and various food processing applications. We saw the potential for the aqueous coating of tablets and capsules.
Continuous Tablet Coating Machines
Thomas Processing’s continuous tablet coater is known as the CTC model. It is built on the same fully perforated side-vented pan technology that came from our Accela-Cota developments over 50 years ago. The tablets are fed into one end of the drum using a weigh belt that precisely controls the flowrate of the product.
After entering the drum, the tablets move to a perforated warming section where warm air is drawn through the bed to warm the tablets before coating. From there, the tablets pass under the first of 22 spray nozzles. The spray bar from Thomas Processing with Schlick anti-bearding inserts provide the best resistance to bearding and offer easy cleanability for minimum downtime in your flow of production.
Air flow is introduced into the bed from behind and above the nozzles. It flows into the bed parallel to the spray and exits underneath the tablet bed. This specific configuration was chosen to ensure all air passes through the tablets transferring all the heat to the tablets before exiting. From the last spray gun, the tablets move through a kind of short cure/drying zone before being discharged. After that, tablets are continuously discharged into waiting containers.
Optimizing Your Coating Systems
The innovation does not stop there either. The older continuous tablet coaters came with issues during startup and shutdown. For optimal coating, the drum must be filled before the coating begins. The first tablets to be discharged from the coater would have only gone under a small part of the spray section and would not be adequately coated.
This issue would impact production when the drum was initially loaded and at the end of the production run when it was emptied. The more frequently the drum is stopped and emptied, the less efficient the continuous coater will operate.
Thomas Processing brought a novel approach to the startup and shutdown problem. The tablet bed is initially charged full of tablets. After this, all the guns are turned on, and the tablets are coated with a low weight gain coating to give them protection from erosion. The guns are then turned off before being activated one by one in a sequence that is proprietary to Thomas Processing.
This sequence results in all tablets coming out with precisely the required weight gain. No tablets are under-coated or over-coated. Once all guns are on, the discharge end is opened, and the unit is switched to continuous mode. When the coater is stopped and emptied, this process is reversed.
Coating Uniformity Impacts End Performance
The coating on a tablet influences how it reacts in the human body and the rate of release for the medication. Different release times or dosage forms are chosen for different medications based on their intended application. Poor uniformity also affects the overall appearance of the tablet itself. In inferior systems, you’ll see obvious variations from tablet to tablet.
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Thanks to the shallow bed depth of the continuous coater, they produce a much more uniform coating than a batch coater for any given process. This difference in coating protects the integrity of the end product and ensures better performance for the end user. Investing in the right tablet coater for your operations enhances all aspects of your tablets.
Ready to Take Advantage of Continuous Production?
The continuous tablet coaters from Thomas Processing come from a long pedigree of innovation and dedication to delivering quality. We’ve spent many years ensuring they offer optimal levels of uniformity, functionality, and cleanability for your operations. They are flexible pieces of equipment suitable for a wide variety of products and medications throughout the pharmaceutical industry. To learn more about our CTC coater model and all the services offered by Thomas Processing, contact us today.