[Updated 3/10/2020]

Elemental impurities in drug products may arise from several sources; they may be residual catalysts that were added intentionally in synthesis or may be present as impurities (e.g., through interactions with processing equipment or container/closure systems or by being present in components of the drug product). Because elemental impurities do not provide any therapeutic benefit to the patient, their levels in the drug product should be controlled within acceptable limits. There are three parts of this guidance:

• The evaluation of the toxicity data for potential elemental impurities

• The establishment of a permitted daily exposure (PDE) for each element of toxicological concern

• The application of a risk-based approach to control elemental impurities in drug products