Control and analysis of alkyl and benzyl halides and other related reactive organohalides as potential genotoxic impurities in active pharmaceutical ingredients (APIs).

This paper continues the review of the relevant scientific literature associated with the control and analysis of potential genotoxic impurities (PGIs) in active pharmaceutical ingredients (APIs). The initial review [D.P. Elder, A. Teasdale, A.M. Lipczynski, J. Pharm. Biomed. Anal. 46 (2008) 1-8.] focused on the specific class of sulfonate esters but in this instance reference is made to the analysis of alkyl and benzyl halides and other related reactive organohalide alkylating agents. Such reactive materials are commonly employed in pharmaceutical research and development as raw materials, reagents and intermediates in the chemical synthesis of new drug substances. Consequently a great deal of attention and effort is extended by the innovative and ethical pharmaceutical industry to ensure that appropriate and practicable control strategies are established during drug development to ensure residues of such agents, as potential impurities in new drug substances, are either eliminated or minimized to such an extent so as to not present a significant safety risk to volunteers and patients in clinical trials and beyond. The reliable trace analysis of such reactive organohalides is central to such control strategies and invariably involves a state-of-the-art combination of high-resolution separation science techniques coupled to sensitive and selective modes of detection. This article reports on the most recent developments in the regulatory environment, overall strategies for the control of alkylating agents and the latest developments in analysis culminating in a literature review of analytical approaches. The literature is sub-categorized by separation technique (gas chromatography (GC), high-performance liquid chromatography (HPLC), thin layer chromatography (TLC) and capillary zone electrophoresis (CZE)) and further tabulated by API type and impurity with brief method details and references. As part of this exercise, a selection of relevant pharmacopoeial monographs was also reviewed. The continued reliance on relatively non-specific and insensitive TLC methodologies in several monographs was noteworthy.