Information for health care professionals
Tablet and capsule coatings
Not all tablets are coated but of those that are film coatings are the most common although several older preparations, such as Nurofen, still have sugar coats.
There are several reasons for coating tablets, including to:
- Protect a tablet ingredient from decomposition during storage, for example by light or moisture
- Mask an unpleasant taste or odour
- Aid identification of a tablet
- Enhance the appearance of a tablet.
There are however tablet coatings that perform a pharmaceutical function, such as conferring controlled or enteric release on the dosage form.
Extended Release
Extended release tablets have a coating that once the tablet has been ingested slowly releases the drug into the gastrointestinal tract. The active ingredients may be released continuously or in repeated small doses over time, usually for a period of 12 hours or more.
The aim is to increase the time period during which a therapeutic drug concentration level in the blood is maintained, although it may also be to increase the release time for drugs that can cause local irritation in the stomach or intestines if they are released too quickly. In addition extended release preparations may help to improve patient compliance due to the reduced dosage frequency.
Enteric Coatings
Enteric coatings are resistant to acid in the stomach and hence allow a tablet to pass through the stomach intact, preventing direct contact between the drug and the stomach. The medicament is only released once the tablet reaches the small intestine and the coating dissolves in the less acidic environment. Such coatings are useful when a drug may be inactivated by the acid in the stomach, where it may irritate the stomach lining or when bypassing the stomach aids absorption of the drug.
Capsules
Capsules consist of the active ingredient(s) together with a combination of different excipients similar to those used in tablets, contained within either a hard or soft gelatin shell.
Hard gelatin shells are clear, colourless and essentially tasteless, although colourings and markings can easily be added for light protection and ease of identification. The majority of these 'two piece' capsules are filled with powdered formulations although enteric-coated or extended-release preparations are available in which the drug is presented as specially coated pellets or beads encased within the shell.
Soft gelatin shells may be transparent or opaque and can be coloured or flavoured if desired. Such capsules allow liquids to be given as solid dosage forms, and in the case if enteric-resistant or extended-release preparations the shell itself is specially coated.
Other links in this section:
- Information on tablet formulation.
- How tablets work.
- Clinical and legal reasons why tablet
crushing and capsule opening should be avoided.
- Protocol providing guidance on medication
administration for patients with swallowing difficulties (dysphagia),
including those with percutaneous endoscopic gastronomy (PEG) and percutaneous
endoscopic jejunostomy (PEJ) tubes in situ.
- Comprehensive list of liquid and non-oral alternatives to tablet or capsule formulations.
