Glucuronidation of diflunisal in liver and kidney microsomes of rat and man

Brunelle, F M; Verbeeck, Roger K.

doi:10.3109/00498259609046694

Cited by 21 publications

(7 citation statements)

References 28 publications

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“…In this study, the formation of M3G was determined (Table 1). There was no measurable M3G formation in kidney microsomal incubations, which is consistent with the results reported by Brunelle and Verbeeck (1996). CRI did not affect hepatic glucuronidation of morphine at the 3-position, whereas the formation of M3G was decreased by ϳ24% in the CPF ( p ϭ 0.06) and the CRI ( p ϭ 0.07) groups compared with the control group.…”

Section: Yu Et Alsupporting

confidence: 81%

Effect of Chronic Renal Insufficiency on Hepatic and Renal Udp-Glucuronyltransferases in Rats

Yu¹,

Ritter²,

Krieg³

et al. 2006

Drug Metab Dispos

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ABSTRACT:Significant evidence exists regarding altered CYP450 enzymes in chronic renal insufficiency (CRI), although none exists for the phase II enzymes. The objective of this study was to investigate the effect of CRI on hepatic and renal UDP-glucuronyltransferase (UGT) enzymes. Three groups of rats were included: CRI induced by the 5/6th nephrectomy model, control, and control pair-fed (CPF) rats. UGT activities were determined in liver and kidney microsomes by the 3-and 17-glucuronidation of ␤-estradiol (E2-3G and E2-17G), glucuronidation of 4-methylumbelliferone (4-MUG), and 3-glucuronidation of morphine (M3G). UGT isoforms responsible for these catalytic activities were screened using recombinant rat UGT1A1, UGT1A2, UGT1A3, UGT1A7, UGT2B2, UGT2B3, and UGT2B8. UGT protein levels were examined by Western blot analysis using polyclonal antibodies. There was no significant difference between CRI and CPF rats in hepatic and/or renal E2-3G (UGT1A1), E2-17G (UGT2B3), 4-MUG (UGT1A6), and M3G (UGT2B1) formation. Formation of E2-17G and 4-MUG in the liver and E2-3G and 4-MUG in the kidney was significantly reduced (p < 0.05) in CPF and CRI rats compared with control rats. The down-regulated glucuronidation activities were accompanied by corresponding reductions in protein content of specific UGT isoforms. These results suggest that CRI does not seem to influence the protein levels or catalytic activity of most of the major hepatic or renal UGT enzymes. The observed down-regulation of hepatic and renal UGTs in CRI and CPF rats could be caused by restricted food intake in these groups of rats.

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Section: Yu Et Alsupporting

confidence: 81%

Effect of Chronic Renal Insufficiency on Hepatic and Renal Udp-Glucuronyltransferases in Rats

Yu¹,

Ritter²,

Krieg³

et al. 2006

Drug Metab Dispos

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“…Brunelle and Verbeeck (1993) investigated the effect of saccharolactone on the acyl glucuronidation of diflunisal in rat liver microsomes and found that the maximum rate increased 2-fold with the addition of 4 mM saccharolactone. Follow-up experiments showed similar results both in other microsomal systems (human) (Brunelle & Verbeeck 1996), and in-vivo (rat) (Brunelle & Verbeeck 1997). Other investigators have found similar results, supporting the use of saccharolactone in in-vitro glucuronidation experiments (Gigon & Bickel 1979;Haaz et al 1997;Kemper & Nabb 2005).…”

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confidence: 67%

Effect of the β-glucuronidase inhibitor saccharolactone on glucuronidation by human tissue microsomes and recombinant UDP-glucuronosyltransferases

Oleson

Court

2008

Journal of Pharmacy and Pharmacology

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Glucuronidation studies using microsomes and recombinant UDP-glucuronosyltransferases (rUGTs) can be complicated by the presence of endogenous β-glucuronidases leading to underestimation of glucuronide formation rates. Saccharolactone is the most frequently used β-glucuronidase inhibitor, although as of yet it is not clear whether this reagent should be routinely added to glucuronidation incubations. Here we determined the effect of saccharolactone on eight different UGT probe activities using pooled human liver microsomes (pHLMs) and rUGTs. Despite the use of buffered incubation solutions it was necessary to adjust the pH of saccharolactone solutions to avoid effects (enhancement or inhibition) of lowered pH on UGT activity. Saccharolactone at concentrations ranging from 1 to 20 mM failed to show enhancement of any of the glucuronidation activities evaluated that could be considered consistent with inhibition of β-glucuronidase. However, for most activities, higher saccharolactone concentrations resulted in a modest degree of inhibition. The greatest inhibitory effect was observed for 5-hydroxytryptamine and estradiol glucuronidation by pHLMs with 35% decrease at 20 mM saccharolactone concentration. Endogenous β-glucuronidase activities were also measured using various human tissue microsomes and rUGTs with estradiol-3-glucuronide and estradiol-17-glucuronide as substrates. Glucuronide hydrolysis was observed for pHLMs, lung microsomes, and insect-cell expressed rUGTs, but not for kidney or intestinal microsomes, or HEK293 microsomes. However, the extent of hydrolysis was relatively small representing only 9 to 19% of the glucuronide formation rate measured in the same preparations. Consequently, these data do not support the routine inclusion of saccharolactone in glucuronidation incubations and, if used, saccharolactone concentrations should be titrated to achieve activity enhancement without inhibition.

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“…Carboxylate NSAIDs are excreted to a variable extent in vivo as glucuronides, either as the conjugate of the parent carboxylic acid or a hydroxylated metabolite, with only a small fraction of the dose eliminated as unchanged drug in urine [1]. NSAID metabolism has also been investigated in vitro , particularly with human liver microsomes (HLM) as the enzyme source [2–4], and the liver is normally considered the major organ responsible for drug metabolic clearance [5]. However, significant glucuronidation activity towards endogenous compounds and xenobiotics has been reported for human kidney tissue.…”

Section: Introductionmentioning

confidence: 99%

Aldosterone glucuronidation by human liver and kidney microsomes and recombinant UDP‐glucuronosyltransferases: Inhibition by NSAIDs

Knights¹,

Winner²,

Elliot³

et al. 2009

Brit J Clinical Pharma

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WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Carboxylic acid NSAIDs are extensively glucuronidated as either the parent drug or hydroxylated metabolites and UGT2B7 is ranked highest in terms of NSAIDglucuronidation activity.• NSAIDs cause adverse renal effects including sodium and water retention and hyperkalaemia.• In human kidney the mineralocorticoid aldosterone is glucuronidated directly to form aldosterone 18b-glucuronide. WHAT THIS STUDY ADDS• Human liver and kidney microsomes and UGT1A10 and UGT2B7 catalyze aldosterone18b-glucuronidation.• Non-selective NSAIDs inhibit renal and hepatic aldosterone18b-glucuronidation and in vivo this may lead to elevated intra-renal concentrations of this hormone.• Common involvement of UGT2B7 in NSAID and aldosterone glucuronidation predicates an intra-renal NSAID-aldosterone interaction that may explain in part the clinical observations of variable effects of NSAIDs on electrolytes, fluid retention and blood pressure. AIMSTo characterize: i) the kinetics of aldosterone (ALDO) 18b-glucuronidation using human liver and human kidney microsomes and identify the human UGT enzyme(s) responsible for ALDO 18b-glucuronidation and ii) the inhibition of ALDO 18b-glucuronidation by non-selective NSAIDs. METHODSUsing HPLC and LC-MS methods, ALDO 18b-glucuronidation was characterized using human liver (n = 6), human kidney microsomes (n = 5) and recombinant human UGT 1A1, 1A3, 1A4, 1A5, 1A6, 1A7, 1A8, 1A9, 1A10, 2B4, 2B7, 2B10, 2B15, 2B17 and 2B28 as the enzyme sources. Inhibition of ALDO 18b-glucuronidation was investigated using alclofenac, cicloprofen, diclofenac, diflunisal, fenoprofen, R-and S-ibuprofen, indomethacin, ketoprofen, ketorolac, meclofenamic acid, mefenamic acid, S-naproxen, pirprofen and tiaprofenic acid. A rank order of inhibition (IC50) was established and the mechanism of inhibition investigated using diclofenac, S-ibuprofen, indomethacin, mefenamic acid and S-naproxen. RESULTSALDO 18b-glucuronidation by hepatic and renal microsomes exhibited Michaelis-Menten kinetics. Mean (ϮSD) Km, Vmax and CLint values for HLM and HKCM were 509 Ϯ 137 and 367 Ϯ 170 mM, 1075 Ϯ 429 and 1110 Ϯ 522 pmol min -1 mg -1 , and 2.36 Ϯ 1.12 and 3.91 Ϯ 2.35 ml min -1 mg -1 , respectively. Of the UGT proteins, only UGT1A10 and UGT2B7 converted ALDO to its 18b-glucuronide. All NSAIDs investigated inhibited ALDO 18b-G formation by HLM, HKCM and UGT2B7. The rank order of inhibition (IC50) of renal and hepatic ALDO 18b-glucuronidation followed the general trend: fenamates > diclofenac > arylpropionates. CONCLUSIONA NSAID-ALDO interaction in vivo may result in elevated intra-renal concentrations of ALDO that may contribute to the adverse renal effects of NSAIDs and their effects on antihypertensive drug response.

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Glucuronidation of diflunisal in liver and kidney microsomes of rat and man

Cited by 21 publications

References 28 publications

Effect of Chronic Renal Insufficiency on Hepatic and Renal Udp-Glucuronyltransferases in Rats

Effect of Chronic Renal Insufficiency on Hepatic and Renal Udp-Glucuronyltransferases in Rats

Effect of the β-glucuronidase inhibitor saccharolactone on glucuronidation by human tissue microsomes and recombinant UDP-glucuronosyltransferases

Aldosterone glucuronidation by human liver and kidney microsomes and recombinant UDP‐glucuronosyltransferases: Inhibition by NSAIDs

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