Impurities in Active Pharmaceutical Ingredients and Drug Products: A Critical Review

The presence of impurities in active pharmaceutical ingredients (APIs) and drug products represents a risk to patients' health. Such substances are related to diverse side effects and may have mutagenic potential. That's why it is necessary to establish acceptable limits for these by-products, to minimize the risk associated with medicinal therapy. This work focused on presenting a critical review of relevant points related to the presence of impurities in pharmaceuticals. The main legislation and guidelines from the FDA, EMA, ICH, and Pharmacopeias about the subject were evaluated, and recent articles related to the topic were searched in Scopus, ScienceDirect, PubMed, and Web of Science from 2013 to 2023. Additionally, the analytical techniques used for quantifying impurities were discussed, along with relevant tests for assessing the toxicological and mutagenic risks of these by-products. Recent legislation, including ICH Q3A (R2), ICH Q3B (R2), ICH M7 (R2), ICH Q3D (R2), ICH Q3C (R9), ICH Q3E, ICH Q6A, ICH M3 (R2), as well as FDA and EMA guidelines, highlights a comprehensive and effective framework for controlling impurities in pharmaceuticals. Despite this, there remains a lack of harmonization and standardized procedures across different regions. From the review of scientific literature, we observed that advancements in analytical techniques have significantly improved the sensitivity and selectivity in detecting impurities and degradation products. This underscores the ongoing commitment of health agencies and the pharmaceutical industry to ensure the safety and efficacy of medicinal products.