Journal of Chromatography A, 1240 (2012) 52–58 Contents lists available at SciVerse ScienceDirect Journal of Chromatography A j our na l ho me p ag e: www.elsevier.com/locate/chroma Removal of potentially genotoxic acetamide and arylsulfonate impurities from crude drugs by molecular imprinting György Székely a,b,∗ , Emelie Fritz a,∗∗ , Joao Bandarra b , William Heggie b , Börje Sellergren a a INFU, Technische Universität Dortmund, 44221 Dortmund, Germany b Hovione FarmaCiencia SA, R&D, Lisbon, Portugal a r t i c l e i n f o Article history: Received 10 February 2012 Received in revised form 26 March 2012 Accepted 28 March 2012 Available online 5 April 2012 Keywords: Molecular imprinting Genotoxic impurities API purification Solid-phase extraction a b s t r a c t The present study describes the synthesis and preliminary testing of molecularly imprinted polymers (MIPs) as scavenger resins for removal of the genotoxic impurities (GTI) acetamide and arylsulfonates from active pharmaceutical ingredients (API). The MIPs were synthesized as monoliths using acetamide or methyl tosylate respectively as templates. The polymers were crushed and subsequently tested in the batch and chromatographic mode for template recognition and potential removal efficiency. Both the acetamide and the tosylate MIPs exhibited a strong memory effect for their templates and selectivity with respect to model APIs. For instance the MIP for acetamide preferentially retained acetamide over other amides, such as formamide, acrylamide, methacrylamide, benzamide and N-tert-butylacrylamide. More- over, passing model API crude contaminated with the acetamide through the MIPs led to the quantitative removal of acetamide. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Purification of pharmaceutical drug products is currently a crit- ical issue to the industry [1]. An impurity in a drug substance as defined by the International Conference on Harmonisation Guide- lines is any component of the drug substance that is not the chemical entity defined as the drug substance [2]. Genotoxins are a subgroup of pharmaceutical impurities which are substances that possess a risk of being carcinogenic to humans and on genetic level promote mutations, rearrangement of chro- mosomal material or other damage to DNA [3]. The synthesis of pharmaceutical products often involves the use of such reactive reagents for the formation of intermediates and APIs. Low levels of reagents or by-products may therefore be present in the final drug product as impurities. Some of these impurities are chemically reactive and may have unwanted toxicities, including genotox- icity and carcinogenicity, with severe impact on product risk assessment. Recently GTIs have gained increased attention and pharmaceu- tical regulatory authorities carry on issuing guidelines that restrict ∗ Corresponding author at: Hovione FarmaCiencia SA, Lisbon, Portugal and INFU, Technische Universität Dortmund, Dortmund, Germany. Tel.: +351 219829136/+49 2317554082; fax: +351 219829388/+49 2317554234. ∗∗ Corresponding author at: INFU, Technische Universität Dortmund, Dortmund, Germany. Tel.: +49 2317554082; fax: +49 2317554234. E-mail addresses: gszekely@hovione.com, gyoergy.szekely@tu-dortmund.de (Gy. Székely), e.fritz@infu.uni-dortmund.de (E. Fritz). the limits of genotoxins in medicines. The European Medicines Agency (EMEA) issued in June 2006 a guideline summarizing the allowed limits of GTIs, which was implemented in January 2007 [2]. If the formation of genotoxins in APIs cannot be prevented, purification of the API should be performed until the genotoxin is removed down to satisfying and practicable levels. The focus of this report is on two common GTIs: arylsulfonates and acetamide. There are many sources of genotoxic arylsulfonate contamination in APIs. For instance p-toluenesulfonic acid (TsOH) is widely used by pharmaceutical manufacturers in order to form salt of the final API because the obtained tosylate salts have increased solubility in water and are prone to crystallize easily. Esterification may happen between TsOH and residual solvents such as methanol which results in the genotoxic by-product methyl tosylate. Similar esterification occurred in one of the leader health-care companies which led to the global recall of Viracept AIDS drug [4,5]. Acetamide is a possible carcinogen to humans based on rodent toxicity data and a common potentially genotoxic impurity in phar- maceutical manufacturing. Pharmaceutical authorities have set a limit of 1.5 g/day – the threshold of toxicological concern (TTC) – for most known and all suspect carcinogens, unless experimental evidence can justify higher limits. Acetamide and TsOH fall into this category thus their concentration limit in drugs can be calculated by dividing the TTC value by the maximum daily dose (g/day) of the drug giving the allowable limits in ppm [6]. Acetamide can form through hydrolysis of acetonitrile when using aqueous acetonitrile together with a strong acid. These cases emphasize the importance of profound GTI removal from APIs. It is well-established that the purification process plays 0021-9673/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.chroma.2012.03.092