UDP-glucuronosyltransferase 1-9 (UGT1A9) (UGT1A9)

Human UDP-glucuronosyltransferase 1-9 (UGT1A9) is a vital Phase II drug-metabolizing enzyme primarily localized in the liver and kidneys [1, 4, 10]. It belongs to the UGT1A family and is responsible for the glucuronidation of a diverse range of xenobiotics and endobiotics, including phenols, steroids, and bilirubin [1, 3, 4]. By conjugating these lipophilic substrates with glucuronic acid, UGT1A9 enhances their water solubility, which is essential for their subsequent excretion through the urine or bile [4, 10, 13]. The enzyme is a major determinant in the pharmacokinetics of several high-profile drugs, such as the immunosuppressant mycophenolic acid and the anesthetic propofol [1, 5, 9]. Genetic variations in the UGT1A9 gene, particularly the UGT1A9*22 polymorphism, are known to cause significant inter-individual differences in drug clearance and are linked to adverse drug reactions like severe diarrhea or hepatotoxicity [1, 5, 9, 12]. Furthermore, UGT1A9 is involved in drug-drug interactions where inhibitors can elevate the plasma concentrations of co-administered substrates to toxic levels [5, 7, 14]. Understanding UGT1A9 activity is therefore crucial for optimizing drug dosing and ensuring patient safety in clinical practice [5, 8, 9].

Other names

UGT1A9HLUGP4LUGP4UDPGTUDPGT 1-9UGT-1IUGT1-09UGT1-9UGT1.9UGT1AIUGT1IUGT1A9SUDP glucuronosyltransferase family 1 member A9

UGT1A9 primarily functions as a metabolic enzyme that catalyzes the glucuronidation of drugs, a process where a glucuronic acid moiety is covalently attached to the substrate to increase its water solubility and facilitate excretion [3, 10, 13]. Drugs can interact with UGT1A9 as substrates, which are cleared by the enzyme, or as inhibitors, which block the enzyme's activity and can lead to drug-drug interactions [6, 7, 14].