Critical review on establishment and availability of impurity and degradation product reference standards, challenges faced by the users, recent developments, and trends

The reference standards of impurities (IMPs) and degradation products (DPs) are required by pharmaceutical industry and quality testing laboratories the world over to comply with stringent thresholds prescribed in the compendial tests. In all the major pharmacopoeias, more and more monographs are currently being modified to include tests for IMPs and DPs. This review does a critical analysis of the whole situation with respect to development, supply, costs, etc. of reference standards of IMPs and DPs. It is found that significant differences exist not only regarding these aspects, but even the definitions, nomenclatures, types, instructions for use, storage, handling, etc. Typical suggestions have been put forth, which may prove handy to Pharmacopoeial Discussion Group and the pharmacopoeial agencies during harmonization exercise. The write-up also discusses difficulties faced by the users, recent developments and the trends.