Drug Impurity

Drug impurities are process-related compounds and degradation products linked to specific drug substances. Most entries carry the name of their parent drug and arise from starting materials, side reactions or breakdown during storage. ABZ-amine is related to the anthelmintic albendazole, and olanzapine ketolactam is a degradation product of olanzapine. The range extends from cetirizine methyl ester, an ester of the antihistamine cetirizine, to Calcitriol Impurities D and Gefitinib impurity 2. Researchers use such compounds in impurity profiling, in identifying unknown chromatographic peaks and in studies of degradation pathways. Environmental contaminants and stereoisomers of research compounds are grouped under Impurities & Reference Standards instead.