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Guidance 18: Impurities in drug substances and drug products
18.1 Impurities in drug substances and drug products
Identifying and describing the impurities that are present in prescription medicines is important for safety reasons, since some impurities can be hazardous to the health of the person using the medicine.
Impurities can arise during the process of manufacturing or storage of medicines.
They can be either:
- related to the drug substance (e.g. starting materials, by-products, intermediates that arise during synthesis, degradation products)
- unrelated to the drug substance (e.g. residual solvents, residual metal catalysts, reagents used during synthesis, chemicals that leach from the container).