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This glossary gives definitions for the main regulatory terms used on this website and in European Medicines Agency (EMA) documents.

Click on a letter below to see terms beginning with that letter.

Disclaimer: EMA has developed the definitions in this glossary to help this website's users understand regulatory terminology. Definitions may differ from those given in European Union legislation.


well-established use

When an active ingredient of a medicine has been used for more than 10 years and its efficacy and safety have been well established. In such cases, application for marketing authorisation may be based on results from the scientific literature.

For more information, see Directive 2001/83/EC of the European Parliament and of the Council.

withdrawal period

The time that must elapse between the last administration of a veterinary medicine and the slaughter or production of food from that animal, to ensure that the food does not contain levels of the medicine that exceed the maximum residue limit.

For more information, see maximum residue limits.

working party

A group of European experts that can be consulted by the European Medicines Agency's committees on scientific issues in their area of expertise. Working parties are often given tasks linked to the evaluation of applications and the drafting or revision of guidance.

For more information, see working parties and other groups.


The submission of a single application for a variation that affects more than one marketing authorisation from the same marketing authorisation holder.

For more information, see worksharing: questions and answers.