Elemental impurities are trace substances present in finished dosage forms that originate from either active pharmaceutical ingredient (API) and excipients or from the manufacturing equipment and catalysts used in the production process.
Drug firms are required to test for elemental impurities. Previously the focus has been on quantifying impurities. However, in 2014 the International Council for Harmonization (ICH) issued guideline Q3D introducing risk-based methods for testing finished drugs that take potential sources of impurities into account.
While Q3D increased the list of elements drug firms must monitor from 14 to 24 it also provided scope for the extent of quality control testing to be reduced provided there is adequate control.
Q3D in Ph. Eur.
This month the European Directorate for the Quality of Medicines (EDQM) announced how it plans to integrate Q3D into an update of the European Pharmacopoeia (Ph. Eur.) due to be published next January.
In addition to a chapter setting out the scope of Q3D the Strasbourg, France-based agency said the update will introduce elemental impurities testing requirements in the General monograph on substances for pharmaceutical use (2034).
Furthermore, specific elemental impurities tests in monographs on substances of natural origin already included in the European Pharmacopoeia will be retained.
The agency said: “Given the intrinsic nature of elemental impurities in these substances, they are amongst the major potential sources of elemental contamination in medicinal products.”
“The Ph. Eur. Commission has also recommended keeping in particular the different tests for elements for which no Permitted Daily Exposure limits have been established - such as aluminium and iron - in individual monographs.”
In contrast, specific tests for elemental contaminants originating from the production process will be deleted. The EDQM explained that because “these elemental impurities are specific to the production process, they will remain the responsibility of the substance manufacturer.”
Ongoing work
The EDQM also said it will also review existing monographs to determine to what extent they are impacted by Q3D and publish a list of concerned monographs in due course.
“As new data become available, the groups of experts intend to examine opportunities for revision of the set of individual metal tests in monographs in order to align them with newer standards and/or to reflect more closely the actual quality of substances available on the European market.”