In vitro inhibitory effects of non‐steroidal anti‐inflammatory drugs on 4‐methylumbelliferone glucuronidation in recombinant human UDP‐glucuronosyltransferase 1A9—potent inhibition by niflumic acid

The inhibitory potencies of non‐steroidal anti‐inflammatory drugs (NSAIDs) on UDP‐glucuronosyltransferase (UGT) 1A9 activity were investigated in recombinant human UGT1A9 using 4‐methylumbelliferone (4‐MU) as a substrate for glucuronidation. 4‐MU glucuronidation (4‐MUG) showed Michaelis‐Menten kinetics with a Km value of 6.7 µM. The inhibitory effects of the following seven NSAIDs were investigated: acetaminophen, diclofenac, diflunisal, indomethacin, ketoprofen, naproxen and niflumic acid. Niflumic acid had the most potent inhibitory effect on 4‐MUG with an IC50 value of 0.0341 µM. The IC50 values of diflunisal, diclofenac and indomethacin were 1.31, 24.2, and 34.1 µM, respectively, while acetaminophen, ketoprofen and naproxen showed less potent inhibition. Niflumic acid, diflunisal, diclofenac and indomethacin inhibited 4‐MUG competitively with Ki values of 0.0275, 0.710, 53.3 and 69.9 µM, respectively, being similar to each IC50 value. In conclusion, of the seven NSAIDs investigated, niflumic acid was the most potent inhibitor of recombinant UGT1A9 via 4‐MUG in a competitive manner. Copyright © 2005 John Wiley & Sons, Ltd.

[1]  J. Clements,et al.  Clinical Pharmacokinetics of Paracetamol , 1982, Clinical pharmacokinetics.

[2]  C. King,et al.  Glucuronidation of carboxylic acid containing compounds by UDP-glucuronosyltransferase isoforms. , 2004, Archives of biochemistry and biophysics.

[3]  C. Guillemette,et al.  In Vitro Characterization of Hepatic Flavopiridol Metabolism Using Human Liver Microsomes and Recombinant UGT Enzymes , 2002, Pharmaceutical Research.

[4]  D. Greenblatt,et al.  Interindividual variability in acetaminophen glucuronidation by human liver microsomes: identification of relevant acetaminophen UDP-glucuronosyltransferase isoforms. , 2001, The Journal of pharmacology and experimental therapeutics.

[5]  H. Kamimura,et al.  In Vitro inhibitory effects of non‐steroidal antiinflammatory drugs on UDP‐glucuronosyltransferase 1A1‐catalysed estradiol 3β‐glucuronidation in human liver microsomes , 2005, Biopharmaceutics & drug disposition.

[6]  L. Wienkers,et al.  Characterization of bropirimine O-glucuronidation in human liver microsomes , 2003, Xenobiotica; the fate of foreign compounds in biological systems.

[7]  F. Mosca,et al.  Inhibition of mycophenolic acid glucuronidation by niflumic acid in human liver microsomes , 2002, European Journal of Clinical Pharmacology.

[8]  R. Obach,et al.  Impact of nonspecific binding to microsomes and phospholipid on the inhibition of cytochrome P4502D6: implications for relating in vitro inhibition data to in vivo drug interactions. , 2003, Drug metabolism and disposition: the biological fate of chemicals.

[9]  A. Ford-hutchinson,et al.  The binding of paracetamol to plasma proteins of man and pig , 1973, The Journal of pharmacy and pharmacology.

[10]  Yoshiro Saito,et al.  Human liver UDP-glucuronosyltransferase isoforms involved in the glucuronidation of 7-ethyl-10-hydroxycamptothecin , 2001, Xenobiotica; the fate of foreign compounds in biological systems.

[11]  M. Manns,et al.  Expression of the UDP-glucuronosyltransferase 1A Locus in Human Colon , 1998, The Journal of Biological Chemistry.

[12]  A. Pietrabissa,et al.  Mycophenolic acid glucuronidation and its inhibition by non-steroidal anti-inflammatory drugs in human liver and kidney , 2000, European Journal of Clinical Pharmacology.

[13]  A. Pietrabissa,et al.  Inhibition of human liver phenol sulfotransferase by nonsteroidal anti-inflammatory drugs , 2000, European Journal of Clinical Pharmacology.

[14]  H. Kamimura,et al.  Effects of β‐estradiol and propofol on the 4‐methylumbelliferone glucuronidation in recombinant human UGT isozymes 1A1, 1A8 and 1A9 , 2004, Biopharmaceutics & drug disposition.

[15]  M. Braun,et al.  Characterization of rat and human UDP-glucuronosyltransferases responsible for the in vitro glucuronidation of diclofenac. , 2001, Toxicological sciences : an official journal of the Society of Toxicology.

[16]  C. Guillemette,et al.  Identification of common polymorphisms in the promoter of the UGT1A9 gene: evidence that UGT1A9 protein and activity levels are strongly genetically controlled in the liver. , 2004, Pharmacogenetics.

[17]  B. Burchell,et al.  Almokalant glucuronidation in human liver and kidney microsomes: evidence for the involvement of UGT1A9 and 2B7 , 2003, Xenobiotica; the fate of foreign compounds in biological systems.

[18]  J. Miners,et al.  Drug glucuronidation in humans. , 1991, Pharmacology & therapeutics.

[19]  A. Prémaud,et al.  IDENTIFICATION OF THE UDP-GLUCURONOSYLTRANSFERASE ISOFORMS INVOLVED IN MYCOPHENOLIC ACID PHASE II METABOLISM , 2005, Drug Metabolism and Disposition.