When buying any tablet, such as vitamins, over-the-counter cold medicine and prescription drugs, you will notice that each tablet has a smooth texture. This is because tablets are coated with sugar or a polymer-based film. Tablets are coated for a variety of reasons, such as making the tablet easy to swallow, covering a foul taste or odour, and stabilising the ingredients. While both sugar and film coatings accomplish these goals, there are pros and cons of using each type of coating.
Sugar Coating Benefits
Sugar coating of tablets has been used since the late 1800s. The sugar coating on a tablet is thick, and it surrounds the medical ingredients, blocking their flavour and stabilising the drug. Sugar coating blocks light and moisture, which can make the drug go bad. The sugar coating on the tablet is the same formula of a sugar coating used on most smooth candies.
Sugar Coating Cons
Sugar coating a tablet greatly increases the size of the tablet. This can make the tablet harder to swallow, and increase costs by increasing the size of packaging. Sugar coating takes much longer than film coating: it can take up to two weeks to finish the coating of the tablets. This style of coating uses several different pieces of equipment, and is difficult to complete on a small scale.
Film Coating Benefits
Film coating of tablets has been used since the early 1970s. The film coating on a pill is made up of a polymer, a plasticiser, colourants and a solvent. Common polymers used are types of cellulose. Plasticisers are materials with low molecular weight that helps break down polymer strands. Common solvents are water and alcohol. Film coating takes at most a few hours to complete and only requires one piece of equipment. Because the process is easier and takes less time, scientists are able to be innovative, creating faster and more efficient ways to film coat a tablet. About 90 per cent of tablets produced in 2010 were film coated.
Film Coating Cons
According to the National Institute for Occupational Safety and Health and the Centers for Disease Control and Prevention, organic, solvent-based film coating causes a lot of pollution when it is manufactured, and the process can put workers' safety at risk due to the toxicity of organic solvents. Many companies are switching to aqueous-based coatings due to harsher government regulation of solvents.
Also, because scientists are trying many different ways to film coat tablets, many machines can create a variety of coating defects, such as over-wetting or over-drying the tablet, mottled colour, chipping of the tablet, and twinning, which causes tablets to stick together.
Check the ingredients of your tablet's film coating if you have severe allergies to certain food products. Because film coatings come in such a variety of ingredients, you will need to check each type of tablet. For example, the allergy relief tablets Aerius, Histaclar and the Hepatitis B treatment Baraclude contain lactose in the film coatings; some tablet film coatings, such as Pyridoxal 5-Phosphate, contain shellfish ingredients.
- "The Art of Dispensing"; Pill Sugar Coating; Peter MacEwan; 1915
- "National Institute for Occupational Safety and Health"; Organic Solvent Neurotoxicity; 1987
- "Public Health Guidance Note"; Organic Solvents; Environmental Health Unit; 2002
- "Aqueous Polymeric Coatings for Pharmaceutical Dosage Forms"; James McGinity; 2008
- Aerius: Aerius Tablets
- medicines.ie: Histaclar 10mg Film Coated Tablets
- Integrative Psychiatry: Pyridoxal 5-Phosphate by Ecological Formulas 100 caps
- The Medical News: Baraclude