This document is intended to provide guidance to registration applicants on the content and qualification of impurities in new veterinary drug substances intended to be used for new veterinary medicinal products, produced by chemical syntheses and not previously registered in a country, region, or member state.  This guidance does not address new veterinary drug substances used during the clinical research stage of development. The following types of new veterinary drug substances are not covered in this guidance: biological/biotechnological, peptide, oligonucleotide, radiopharmaceutical, fermentation products and semi-synthetic products derived therefrom, herbal products, and crude products of animal or plant origin. 

Impurities in new veterinary drug substances are addressed from two perspectives:

• Chemistry Aspects including classification and identification of impurities, report generation, listing of impurities in specifications, and a brief discussion of analytical procedures; and
• Safety Aspects including specific guidance for qualifying those impurities that were not present, or were present at substantially lower levels, in batches of a new veterinary drug substance used in safety and clinical studies.

This document does not address: (1) extraneous contaminants that should not occur in new veterinary drug substances and are more appropriately addressed as Good Manufacturing Practice (GMP) issues, (2) polymorphic forms, and (3) enantiomeric impurities.

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