Thiopurine hepatotoxicity in inflammatory bowel disease: The role for adding allopurinol

Rupert W L Leong*, Richard B. Gearry, Miles P. Sparrow

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

28 Citations (Scopus)


Background: Immunomodulator therapy with the thiopurine analogues azathioprine or 6-mercaptopurine is commonly prescribed for the treatment of inflammatory bowel disease (IBD). Drug adverse effects and the lack of efficacy, however, commonly require withdrawal of therapy. Allopurinol, a xanthine oxidase inhibitor, was recently evaluated in its role in modifying thiopurine metabolism and improving drug efficacy in IBD. Objective: This article reviews the role and safety of allopurinol co-therapy in the setting of thiopurine hepatotoxicity and/or non-responsiveness in IBD. Methods: Published articles on thiopurines in the treatment of IBD were examined. Conclusion: The addition of low dose allopurinol to dose-reduced thiopurine analogue seems safe but careful monitoring for adverse effects and profiling of thiopurine metabolites is essential. There is evidence of improved immunomodulator efficacy and reduced hepatotoxicity clinically but further confirmatory studies are required before more definitive treatment recommendations can be given.

Original languageEnglish
Pages (from-to)607-616
Number of pages10
JournalExpert Opinion on Drug Safety
Issue number5
Publication statusPublished - Sept 2008
Externally publishedYes


  • 6-methylmercaptopurine
  • 6-tioguanine nudeotides
  • Azathioprine
  • Crohn's disease
  • Doguanine
  • Inflammatory bowel disease
  • Mercaptopurine
  • Metabolites
  • Pharmacogenomics
  • Thiopurine
  • TPMT
  • Ulcerative colitis


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