Cytochrome P450 Enzymes (CYP)
Also known as: CYP enzymes, CYP450, P450 enzymes, cytochrome P450 system
Verified from StatPearls on 06-02-2026Cytochrome P450 enzymes are a group of heme-containing proteins, largely expressed in the liver, that drive the biotransformation of drugs and other foreign compounds. Because a small set of CYP isoforms handles the bulk of pharmaceutical metabolism, variations in CYP activity are central to discussions of drug interactions, pharmacokinetic variability, and dosing considerations. The source definition below, drawn from the National Library of Medicine (NCBI Bookshelf), outlines the role of the CYP system in clinical therapy and drug metabolism.
MedivaScan summary. The authoritative source quote follows below.StatPearls definition
Interindividual variability in drug response remains a major challenge in clinical therapy, with outcomes ranging from treatment failure to serious adverse drug reactions. A significant proportion of this variability arises from differences in drug metabolism, much of which is governed by the cytochrome P450 (CYP) enzyme system. Predominantly expressed in hepatocytes, CYP enzymes catalyze the biotransformation and clearance of a wide array of xenobiotics and potentially toxic compounds. Although these enzymes participate in essential physiological processes, including steroid and hormone synthesis, metabolism of fat-soluble vitamins, and regulation of fatty acids, their most critical impact lies in pharmacokinetics and drug metabolism. A relatively small subset of CYP isoforms accounts for the majority of drug-processing activity, with CYP family enzymes collectively involved in an estimated 80% to 90% of enzymatic drug metabolism. Because drugs can either influence CYP activity or be influenced by it, unintended interactions may arise, altering therapeutic efficacy or increasing toxicity. Understanding how drugs modulate CYP enzymes and how genetic, environmental, and pharmacological factors shape CYP function is essential for optimizing therapy and ensuring safe, effective clinical outcomes.
National Library of Medicine (NCBI Bookshelf)View on source ›Verbatim quote. Last verified 06-02-2026.