Cytochrome P450 (CYP)

Cytochrome P450 (CYP) enzymes are a superfamily of heme-containing proteins primarily located in the endoplasmic reticulum of hepatocytes, though they are expressed in various tissues throughout the body. They play a critical role in the Phase I metabolism of approximately 70-80% of clinical drugs, facilitating their conversion into more polar metabolites for excretion [Source: PubMed, PMID: 23588305]. Beyond xenobiotic metabolism, these enzymes are essential for the synthesis and degradation of endogenous compounds such as steroid hormones, lipids, and vitamins [Source: UniProt, P03372]. In clinical practice, CYPs are major determinants of pharmacokinetic variability; genetic polymorphisms in genes like CYP2D6 and CYP2C19 can lead to significant differences in drug efficacy and safety among individuals [Source: FDA, Table of Pharmacogenetic Associations]. Furthermore, the inhibition or induction of these enzymes by co-administered medications is a leading cause of adverse drug-drug interactions, making them a central focus of drug development and regulatory safety assessments [Source: Wikipedia, Cytochrome P450].

Other names

CYP450Cytochrome P450 monooxygenaseMicrosomal heme-thiolate proteinHeme-thiolate enzymeDrug-metabolizing enzyme

Cytochrome P450 enzymes primarily function as monooxygenases, catalyzing the insertion of one atom of oxygen into an organic substrate while the other oxygen atom is reduced to water. In the context of pharmacology, drugs can act as substrates (metabolized by the enzyme), inhibitors (blocking the metabolism of other drugs), or inducers (increasing enzyme expression and metabolic capacity) [Source: NIH StatPearls, Cytochrome P450 Enzymes].