Liver cytochrome P450 enzyme (CYP)

Liver cytochrome P450 enzymes are a superfamily of hemoprotein monooxygenases predominantly expressed in the liver, responsible for the oxidative metabolism of a vast array of endogenous and exogenous substrates. They function to hydroxylate, oxidize, and conjugate steroids, fatty acids, xenobiotics, and drugs, facilitating their solubilization and excretion. These enzymes are critical for drug detoxification, metabolism, and elimination, and are divided into multiple families based on sequence similarities (e.g., CYP1, CYP2, CYP3, with key isoforms such as CYP3A4, CYP2D6, CYP1A2, CYP2C9, CYP2C19, and CYP2E1). Their actions underlie significant variability in drug response and potential for drug-drug interactions, as drugs may act as substrates, inhibitors, or inducers of specific CYP450 isoforms. Genetic polymorphisms in CYP genes are a major source of inter-individual variability in drug metabolism. As central mediators in drug metabolism, CYP enzymes are key pharmacological targets, and understanding their activity is essential for safe and effective drug therapy.

Other names

Cytochrome P450CYP450CYP enzymesCYP3A4CYP2D6CYP1A2CYP2C9CYP2C19CYP2E1Microsomal monooxygenases

Substrate (metabolized by CYP) Inhibitor (blocks CYP activity, increasing plasma drug levels) Inducer (stimulates CYP expression/activity, leading to faster metabolism) Activator (rare; enhances CYP activity)