Figure 1.

Simplistic representation of the main biotransformation of tamoxifen and its metabolites. The generation of N-desmethyltamoxifen (NDM-TAM) is predominantly catalyzed by CYP3A4/5, whereas especially CYP2D6 is responsible for the formation of 4-hydroxytamoxifen (4OH-TAM) and endoxifen. The activity of metabolites is shown using red to indicate for inactivity and green for activity. The various metabolites are inactivated by UGTs and SULTs, mainly isoform SULT1A1. Abbreviations: CYP: Cytochrome P450 isoenzymes, UGT: UDP-glucuronosyltransferase, SULT: sulfotransferase isoenzyme. Figure based on Jin, et al. [14].