Excipients: Information sources

Last updated: Thursday, October 06, 2016

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When using any information source, do be careful that some excipients have more than one name so make sure you check them all. For example, PEG, polyethylene glycol, E1521, macrogol, and polyoxyethylene glycol can all be terms for the same thing.

Manufacturers’ SPCs are the single most helpful source for identifying the excipients in a particular medicine. You can access them via the eMC, but many SPCs missing from here are available via the MHRA site (e.g. some generic medicines). Generally the information required is in section 6.1 of each SPC. However, note that occasionally an SPC does not list every excipient: those present in ‘trace’ amounts may not be declared. If it is crucial to be sure about excipient content, the only option is to ring manufacturers individually.

Remember that you can use the eMC to help you find a formulation that doesn't contain a particular excipient. If you don't know how to do this, then look at our Guide to the eMC, and particularly pages 3 to 5.

To best manage patients, and to understand the safety of an individual excipient, you have a variety of sources to help you:

  • Expert sites about allergy may offer valuable advice on caring for patients. Examples include the American Academy of Allergy Asthma and Immunology and the British Society for Allergy and Clinical Immunology.
  • Medline and Embase enable retrieval of case reports and reviews of excipient side effects. 
  • There are a few Medicines Q&As on the SPS website about prescribing particular products in lactose and peanut intolerant patients. 
  • Martindale often has a description of common excipients with a summary of known safety issues. 
  • Finally, the book Pharmaceutical Excipients (Pharmaceutical Press) is available online via Medicines Complete, and this gives details of the chemical properties of excipients and their safety. You may not have access to this publication in your Trust, but regional MI centres often have a subscription.