Topic overview

Start with the big picture

Clearance depends on coordinated Phase I enzymes, especially CYP450s, Phase II conjugating enzymes, and efflux transporters. Ligand-activated receptors—including AhR, PXR, and CAR—can increase the expression of particular enzymes and transporters. By contrast, inhibition, inflammatory signals, limited cofactors, and disease can reduce metabolic capacity. Drug and food exposures, genetic and epigenetic variation, age, hormones, pregnancy, and circadian rhythm also contribute to differences in regulation. Additional controls include feedback from accumulated conjugates and post-translational changes that affect CYP lifespan. The broader lesson connects these mechanisms to clinical implications and organizes key regulators for comparison, providing a framework for understanding variable xenobiotic handling without treating any single pathway as the sole determinant.