Importance of metabolism. Mechanistic considerations relevant for toxicological regulation

Abstract

Most xenobiotics do not remain unchanged in the human organism (and in other organisms), but rather are metabolized. The change in chemical characteristics of the thereby produced metabolites as compared with the chemical characteristics of the corresponding parent compounds usually leads to changes in both the desired properties, e.g., therapeutic efficacy, and also in undesired properties, i.e., xenobiotic metabolism usually is toxicologically not neutral, but rather leads in most cases to toxication or detoxication of the respective compound (overview see Oesch-Bartlomowicz and Oesch 2007). Thereby xenobiotic metabolism becomes one of the most important factors controlling the toxicity of the respective compound. This, in turn, makes xenobiotic-metabolizing enzymes to control factors for xenobiotic toxicity.