Interaction of pharmaceutical metabolites with blood proteins and membrane lipids in the view of bioconcentration: A preliminary study based on in vitro assessment.

Pharmaceuticals pose a real threat to the environment, which has been proven in many studies to date. However, still little is known about the transformation products (TPs) of these compounds, which can also interact with organisms, causing adverse effects like noticeable toxicity or bioconcentration. Many recent works confirm that metabolites of pharmaceuticals are present in the environment, and preliminary studies suggest that they may be equally dangerous to or even more so than their parent compounds. Additionally, it has been proven that some of them have high hydrolytic stability, thus they may be persistent in the environment. This property also increases the likelihood that these compounds will be uptaken and accumulated in the tissues of organisms. Therefore, the aim of the present study was to preliminarily estimate the affinity of the transformation products of selected drugs for blood proteins and cell membrane-forming lipids, considered as important sorption phases during distribution in a living organism. In this study, it was shown that although the examined metabolites do not have a strong affinity for membrane lipids, they exhibit relatively strong binding to proteins, which may considerably affect the distribution of TPs in an organism and may indicate a non-classical process of bioconcentration. The results obtained confirm that the TPs of pharmaceuticals should be given much more attention and their potential for bioconcentration should be further determined.