Setting Limits for Genotoxic Impurities in Drug Substances

In December 2002, the Safety Working Party (SWP) of the European Committee for Proprietary Medicinal Products (CPMP) published a “Position paper on the limits of genotoxic impurities”. The European Union intended to supplement a gap in the International Conference on Harmonisation (ICH) guidelines on qualification of impurities, as it was deemed that impurities with genotoxic potential were a special case not specifically covered in terms of qualification by the Q3A and Q3B guidelines. In fact, the SWP’s proposed approach follows a safety factor-based risk assessment process similar to that in ICH Guideline Q3C on limits for residual solvents, rather than a qualification process as described in ICH Q3A and B.