Excipients: Information sources

Last updated: Sunday, December 10, 2023

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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’ SmPCs are the single most helpful source for identifying the excipients in a particular medicine. You can access them via the emc and/or via the MHRA site. Generally, the information required is in section 6.1 of each SmPC. However, note that occasionally an SmPC 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, there are a variety of useful sources:

The SPS website has some guidance to help you, including:

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

Pharmaceutical Excipients (Pharmaceutical Press) describes the chemical properties of excipients and their safety. Your MI centre may have a subscription.

Finally, Medline and Embase enable retrieval of case reports and reviews of excipient side effects.

Presenting your answer 

Once you’ve asked sufficient questions, gathered the information required and assessed it, you’ll need to provide an answer. We can offer you some general guidance on answering clinical problems.