Cytochrome P450 and UDP-glucuronosyltransferase enzymes (CYPs/UGTs)

Cytochrome P450 (CYP) and UDP-glucuronosyltransferase (UGT) enzymes are the most significant superfamilies involved in the Phase I and Phase II metabolism of drugs and endogenous substances (Source: NIH/NCBI). CYPs are heme-thiolate proteins that primarily catalyze oxidative, reductive, and hydrolytic reactions to introduce functional groups into lipophilic molecules (Source: UniProt). UGTs then catalyze the transfer of a glucuronic acid moiety to these functional groups, significantly increasing the water solubility of the compound for excretion (Source: PubMed). These enzymes are primarily localized in the liver but are also present in the intestines, kidneys, and lungs (Source: StatPearls). They play a dual role in pharmacology: they are responsible for the detoxification of many drugs but can also bioactivate certain pro-drugs or pro-carcinogens into toxic intermediates (Source: PubMed). Because many therapeutic agents are substrates, inhibitors, or inducers of these enzymes, they are the leading cause of clinically significant drug-drug interactions (Source: FDA). Furthermore, extensive genetic polymorphisms in genes like CYP2D6, CYP2C19, and UGT1A1 contribute to wide inter-individual variability in drug response and toxicity (Source: PharmGKB). Understanding the interplay between CYPs and UGTs is critical for drug development, dosage optimization, and avoiding adverse drug reactions (Source: NIH).

Other names

Phase I and Phase II drug-metabolizing enzymesCytochrome P450sUDP-glucuronosyltransferasesCYP450 and UGTXenobiotic-metabolizing enzymes

These enzymes facilitate drug clearance through Phase I (oxidation, reduction, or hydrolysis by CYPs) and Phase II (conjugation with glucuronic acid by UGTs) metabolism, converting lipophilic compounds into polar, water-soluble metabolites suitable for excretion (Source: NIH).