Inhibition of human liver phenol sulfotransferase by nonsteroidal anti- inflammatory drugs

M. Vietri, C. De Santi, A. Pietrabissa, F. Mosca, G. M. Pacifici

Research output: Contribution to journalArticlepeer-review


Objective: The aim of this investigation was to study the inhibition of 11 nonsteroidal anti-inflammatory drugs (NSAIDs) on the human liver phenol sulfotransferases (HL-PST) and catechol sulfotransferase (HL-CST). Methods: The activities of HL-PST and HL-CST were measured with 4 μM 4-nitrophenol and 60 μM dopamine (the sulfate acceptors) and 0.4 μM 3'-phosphoadenosine- 5'-phosphosulfate [35S] (the sulfate donor). Samples of liver were obtained from five patients, aged 55-79 years, undergoing clinically indicated hepatectomy. The inhibition curves were constructed with at least five concentrations of the inhibitor. Results: With the exception of piroxicam, NSAIDs inhibited HL-PST, and the estimates of the inhibitory concentration for 50% of responses (IC50; μM) were: 0.02 (mefenamic acid), 3.7 (diflunisal), 5.4 (nimesulide), 9.5 (diclofenac), 30 (salicylic acid), 41 (ketoprofen), 74 (indomethacin), 159 (ibuprofen), 245 (ketoralac) and 473 (naproxen). With 4-nitrophenol as the variable substrate, the inhibition of salicylic acid on HL-PST was non-competitive and the K(i) and K(ies) were 18 μM and 21 μM (n = 5; P = 0.548), respectively. HL-CST was less susceptible than HL-PST to inhibition by NSAIDs, with only five drugs inhibiting this enzyme. The IC50 estimates for these drugs (μM) were 76 (mefenamic acid), 79 (diflunisal), 103 (indomethacin), 609 (salicylic acid) and 753 (diclofenac). Conclusion: The comparison of the IC50 estimates of HL-PST with the therapeutic plasma concentrations of NSAIDs corrected for the plasma unbound fraction was consistent with the view that mefenamic acid and salicylic acid, when administered at therapeutic doses, should impair the hepatic sulfation of those compounds that are substrates of phenol sulfotransferase.

Original languageEnglish
Pages (from-to)81-87
Number of pages7
JournalEuropean Journal of Clinical Pharmacology
Issue number1
Publication statusPublished - 2000


  • Anti-inflammatory drugs
  • Mefenamic acid
  • Sulfotransferase

ASJC Scopus subject areas

  • Pharmacology (medical)
  • Pharmacology, Toxicology and Pharmaceutics(all)


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