• Question: What is the chemistry of shellac and how it is used for the coating of granules for the delayed release of pharmaceuticals?

    Asked by Danielle to Aaron, David, Elaine, Sarah, Zoe on 13 Nov 2014.
    • Photo: Sarah Ashwood

      Sarah Ashwood answered on 13 Nov 2014:

      Shellac is a polymer, and companies use it to coat drugs.
      The enzymes in your mouth and stomach are strong and will immediately start to break down anything you ingest. This can mean that when taking a tablet the drug can be absorbed very quickly. However if it is a particularly sensitive molecule and might be destroyed in the stomach, you would coat it with a polymer such as shellac as this won’t degrade as easily and allows for the drug to still be intact when it is absorbed through your intestines or later in the digestive tract.
      This helps you have the full benefit of the drug, and also ensures that the dosage is correct for the illness/symptoms that you have.

    • Photo: Zoe Roberts

      Zoe Roberts answered on 17 Nov 2014:

      The chemistry of Shellac uses really long molecules (called polymers) that get painted onto your nails (as a liquid) and then you put them under a UV lamp. The UV lamp joins the polymers together creating crosslinks which make the material set on your nails.

      Drug capsules are also made from polymers but these are in place to protect the drug capsule but get broken down by the body.

      There are lots of different types of polymers. The Shellac polymer is not suitable for the body but polymers used in drug capsules are.

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