Prediction of Drug Degradation Pathways leading to Structural Alerts for Potential Genotoxic Impurities
An in-depth analysis of the web-based CambridgeSoft Pharmaceutical Drug Degradation Database, Pharma D3, was conducted in two phases in an attempt to generate some general rules for the prediction of alerting structures for genotoxicity that may arise as a result of degradation. The first phase involved interrogation of the database to determine the nature and frequency of alerting structures present in the degradants. This analysis revealed five functional groups, which account for approximately 70% of the alerting structures found in the degradants within the database: (1) aldehydes; (2) α,β unsaturated carbonyls; (3) aromatic amines, hydroxylamine and its derived esters; (4) epoxides; and (5) polyaromatic hydrocarbons. The second phase of the analysis involved categorizing the major chemical reactions responsible for the generation of the five most prevalent alerting structures. This two-step approach led, in turn, to a proposal for the prediction of functional groups that may have a propensity to degrade to alerting structures not necessarily present in the parent molecule.