Impurities in Drug Substance-An Overview of ICH Q3A, Q3C and M7 Guidelines

Impurities are undesired chemical substances found in pharmaceutical drug products with no therapeutic benefits and, in some cases, can pose a risk to patient safety if their levels exceed a certain limit. Impurities present in the drug substance can affect quality, safety and efficacy of pharmaceutical products causing serious health hazards. Generally, when the pharmaceutical products are free from impurities, they would exert the intended therapeutic response. International Council for Harmonization (ICH) has provided guidelines for impurities in new drug substance (ICH Q3A) that provides guidance on the qualification and control of impurities in new drug substance using different thresholds for their evaluation. The current study provides an overview of ICH Q3A, 3C and M7 guidelines applicable for impurities in drug substances. All these guidelines focuses on safeguarding the safety and quality of drug substances by providing recommendations that address the particular type of impurities involved. The study concludes that by understanding regulations for classification and control of impurities in drug substance it gives an idea for the regulators to prepare and compile the documents required in compliance with standard guidelines.