CYP3A4

CYP3A4 is a cytochrome P450 enzyme found mainly in the liver and intestine. It metabolizes many medications and other compounds, shaping their clearance and effects.

Cytochrome P450: A family of heme-containing enzymes that oxidize diverse compounds, including drugs and endogenous molecules. CYP3A4 is one member of this enzyme family and uses its characteristic heme-based chemistry.
Drug interaction: A change in a drug's effects or concentration caused by another drug, food, or substance. CYP3A4 inhibition or induction is a common mechanism behind interactions.
CYP3A4 gene: The human gene that encodes the CYP3A4 drug-metabolizing enzyme. Its sequence and regulation determine production of the enzyme.
CYP3A4 polymorphism: A genetic variant in CYP3A4 that may alter enzyme expression or function. Variants are studied as one source of person-to-person differences in CYP3A4 activity.
Drug metabolism: The chemical modification of drugs by the body, often enabling their elimination or changing their activity. CYP3A4 is a major catalyst of this process for many medicines.
Ketoconazole: An antifungal medication that strongly inhibits CYP3A4 and can raise concentrations of its substrates. It is a classic example of a potent CYP3A4 inhibitor used to probe drug interactions.
Cytochrome P450 3A: A subfamily of cytochrome P450 enzymes that metabolizes many drugs and endogenous compounds. CYP3A4 belongs to this subfamily, alongside enzymes with overlapping activities.
CYP3A4 induction: An increase in CYP3A4 expression or activity following exposure to regulatory compounds. The magnitude and timing of induction make clinical interaction effects difficult to predict.
Heme: An iron-containing molecular group that binds gases and supports electron-transfer reactions in proteins. Its heme iron binds oxygen and participates in CYP3A4's oxidation reactions.
Rifampicin: An antibiotic that induces several drug-metabolizing enzymes, including CYP3A4. Its induction can accelerate CYP3A4 substrate clearance and reduce drug exposure.

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