Applications

Tablet coating in the drum

The oldest method that exists for coating and finishing pharmaceutical products is particularly effective when it comes to coating large particles that are not compatible with a fluidised bed, such as tablets, capsules or very large pellets.

Basic principle
Inside a slowly-turning drum, the coating fluid is sprayed onto the product surface and simultaneously dried with warm air injected in a continuous current. A slight negative pressure inside the drum ensures a continuous current whilst also preventing the product from falling out of the drum and into the working area during the coating process. A fully homogeneous application and a complete surface seal can be guaranteed with drum coating.

What is most important here is the homogeneous and reproducible spray that delivers optimal droplet size and distribution, as well as low speeds on the coating bed. The resulting highly even coating allows for a high degree of efficiency that can be achieved independent of the tablet's size or shape.

The coating substance is an element of the coating fluid and is sprayed onto the product particles evenly in fine droplets. During this process, the droplets wet the particle and blend together on its surface. The liquid content evaporates and the coating material hardens. This process is repeated during spraying. Once all the liquid has evaporated, the particle is left with a finished coating.