Sugar coating of tablets is not as common in the pharmaceutical industry as it once was, having been superceded by polymer film coating. Nevertheless, a knowledge of the issues that may occur when sugar coating is applied may help to avoid loss of production when the process is used.
1. Benefits of Sugar Coating
There are some clear benefits of sugar-coated pharmaceuticals -
2. Disadvantages of Sugar Coating
The sugar coating is generally water-soluble making it easier to dissolve quickly when it comes into contact with any liquid medium such as gastrointestinal fluids. One purpose of the sugar coating is to protect the drug inside the tablet and act as barrier to external contaminants. It may also hide or mask the unsavoury taste of the drug that some patients may find unpalatable. Sugar coating insulates and masks the colour and texture of the tablet’s core. It may also influence the release of the encased drug in the body.
3. The coating process
The coating process involves the repetitive application of a sucrose-based solution in the coating pan or drum to cover the tablet. Four process steps are commonly employed, in the following order:
The processes are summarised below.
3.1 Sealing (Water Proofing)
3.2 Subcoating
3.3 Grossing (Smoothing)
3.4 Colouring
3.5 Polishing and/or printing
4. Common Problems that can occur during the sugar coating process and their solutions