This Guidelines is used to provide guidance for the quality specifications about the analysis of impurities in chemically synthesized drug substances and their preparations. The Guidelines can also be used as a reference for drug research, manufacture, and the drafting or revising of quality standards. The Guidelines does not cover biological/biotechnology products, peptides, oligonucleotides, radioactive drugs, fermentation products, semi-synthetic products, traditional Chinese medicines, or crude products made from animals and plants.

As the key quality attributes of drugs, impurities can affect the safety and effectiveness of products. Impurities in drug quality standards refer to the impurities in the drugs produced according to the process and with active pharmaceutical ingredients (APIs) and excipients reviewed and approved by the National Medical Products Administration. The impurities are brought into the drugs due to the production process or raw materials, or generated during storage. The impurities do not include new impurities generated by changing the production process or changing the APIs or excipients, or foreign mixed or contaminated substances. If the drug manufacturer changes the production process or introduces new impurities into the API and excipients, it is necessary to revise the original quality standards and apply for approval from the drug regulator. Drugs shall not be mixed with foreign or polluted substances that are not the drugs’ components. Counterfeit and non-standard drugs shall be tested with appropriate and verified analytical methods according to specific conditions when necessary.