On his website, Consultox.com, environmental toxicology expert witness Dr. Roger A Parent writes on generic drugs:
In June 2009 the US FDA’s Office of Generic Drugs issued, “Guidance for Industry; ANDAs: Impurities in Drug Substances” which basically follows the Q3A, Q3B, Q3C ICH guidelines. These guidelines focus on Drug Substances and covers original abbreviated new drug applications (ANDAs), drug master files(DMFs), including Type II DMFs and ANDA supplements for changes in the synthesis or processing of a drug substance.
The guidance provides recommendations for establishing acceptance criteria for impurities in drug substances and recommends that the specifications for a Drug Substance include a list of impurities. A rational for the inclusion or exclusion of impurities should be included. As indicated in the ICH guidelines, if an impurity cannot be identified, then the efforts made to identify the impurity should be included if present at a level greater than the identification threshold given in ICH Q3A. Organic and inorganic impurities should be considered as well as residual solvent.