Pharmaceutical impurities: regulatory perspective for Abbreviated New Drug Applications.

Impurities in drug substances and drug products have been important regulatory issues in the Office of Generic Drugs by having significant impact on the approvability of Abbreviated New Drug Application (ANDAs). This review begins with a discussion of ANDAs and its similarity/differences with NDAs, highlighting the importance of control of pharmaceutical impurities in generic drug product development and regulatory assessment. An overview of the FDA draft guidance documents "ANDAs: Impurities in Drug Substances" and "ANDAs: Impurities in Drug Products" are provided.