Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.5.2 (NQO1)
 6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The characterization of the enzymatic step(s) involved in the reduction of 3'-azido-3'-deoxythymidine (zidovudine)(ZDV) to 3'-amino-3'-deoxythymidine (AMT) was pursued. AMT formation by human liver microsomes was NADPH dependent, enhanced under anaerobic conditions, and increased by flavin adenine dinucleotide (FAD) and FMN. Carbon monoxide inhibited AMT formation by up to 80%. The effect of theophylline (CYP1A substrate), tolbutamide (CYP2C substrate), chlorzoxazone, thiobenzamide, p-nitrophenol, mercaptoethanol, isoniazid (CYP2E substrates), cortisol (CYP3A substrate), ketoconazole, itraconazole, fluconazole, cimetidine, micronazole (CYP inhibitors), methimazole (flavin-containing mono-oxygenase inhibitor), chloramphenicol (undergoes nitroreduction), allopurinol (xanthine oxidase inhibitor) and dicoumarol (DT-diaphorase inhibitor) on AMT formation were studied to see if the reduction reaction was mediated by a particular isozyme. The greatest inhibition was observed with ketoconazole (concentration producing 50% inhibition = 78.0 microM). At this concentration ketoconazole acted as a non-selective inhibitor of several CYP isozymes. Overall, these data suggested that ZDV reduction was probably mediated by both cytochrome P450 isozymes and NADPH-cytochrome P450 reductase. Formation of AMT, as measured by intrinsic clearance (Clint), was significantly increased in microsomes from rats pre-treated with phenobarbitone, dexamethasone and clofibrate (inducers of CYP2B, CYP3A and CYP4A, respectively). Pre-treatment of rats with beta-naphthoflavone and ethanol (CYP1A and CYP2E1 inducers, respectively) had no effect on AMT formation.
 ...
PMID:The metabolism of zidovudine by human liver microsomes in vitro: formation of 3'-amino-3'-deoxythymidine. 805 24

A substantial part of the interindividual variability in response to drugs and xenobiotics is related to genetically-determined impairment in drug metabolism. Several drug-metabolising enzymes are polymorphic in humans and often polymorphisms are strongly related to altered drug biodisposition and to the risk of developing adverse effects. Drugs used in general anaesthesia undergo polymorphic metabolism. Among these, halothane is metabolized by cytochrome P450 (CYP) 2E1 and, to a lesser extent, by CYP3A4 and CYP2A6. CYP2E1 also plays a key role in the metabolism of isoflurane, sevoflurane, enflurane and desflurane. CYP2B6, CYP3A4 and CYP2C9 play a relevant role in the metabolism of ketamine. The enzymes involved in the metabolism of thiopental and etomidate remains to be elucidated. Propofol is metabolized mainly by glucuronidation by uridine diphosphate-glucuronosyltransferases (UGTs) and by hydroxylation by CYP2B6 and CYP2C enzymes. The enzymes SULT1A1 and NQO1 participate in later steps in propofol metabolism. All the above-mentioned anaesthetic-metabolising enzymes are polymorphic in man. The present review analyzes the importance of enzymes in the metabolism of anaesthetics and common polymorphisms related to the biotransformation of general anaesthetics and it raises hypotheses on genetic and non-genetics factors related to altered response to anaesthetics that require further investigation. Based on functional relevance and allele frequencies, we identify the most promising targets for the clinical use of pharmacogenomic techniques in anaesthesia to prevent altered pharmacokinetics or adverse drug effects.
 ...
PMID:Polymorphic drug metabolism in anaesthesia. 1944 86