Figure 2.

Schematic and simplified illustration of drug–drug interaction mediated by the pregnane X receptor. The nuclear receptor PXR is activated by the ligand (e.g., carbamazepine) and forms a heterodimer with the nuclear receptor RXR. The activated PXR complex induces expression of the CYP3A enzyme (mainly in the enterocytes and hepatocytes), and this affects the metabolism of the substrate of CYP3A (abiraterone) resulting in a decreased exposure. CYP3A, cytochrome P450; PXR, pregnane X receptor RXR; retinoid X receptor; ABT, abiraterone; SULT, sulfotransferase