Safety and effectiveness of long-term allopurinol-thiopurine maintenance treatment in inflammatory bowel disease

Inflamm Bowel Dis. 2013 Feb;19(2):363-9. doi: 10.1002/ibd.23021.


Background: Thiopurines are the mainstay of conventional maintenance therapy in inflammatory bowel disease (IBD). Unfortunately, up to 50% of patients discontinue immunosuppressive therapy within 2 years due to intolerance or lack of efficacy. Allopurinol with low-dose thiopurine can optimize thiopurine metabolism for IBD patients with preferential shunting toward 6-methyl mercaptopurine (6-MMP) formation. The aim of this study was to assess long-term maintenance effectiveness and tolerability of allopurinol-thiopurine therapy in a larger multicenter cohort of IBD patients.

Methods: Enrolled patients who failed monotherapy with thiopurines due to a skewed metabolism were subsequently treated with a combination therapy of allopurinol and low-dose thiopurine. Adverse events were monitored and therapeutic adherence was assessed. Seventy-seven IBD patients were enrolled with a mean follow-up of 19 months.

Results: The median 6-thioguanine nucleotide concentration increased from 145 during monotherapy to 271 pmol/8 × 10(8) red blood cell (RBC) after at least 8 weeks of combination therapy while reducing the thiopurine dosage (P < 0.001). In contrast, median 6-MMP concentrations decreased from 10,110 to 265 pmol/8 × 10(8) RBC (P < 0.001). Leukopenia occurred in 12 patients (16%), requiring dose adaptation. Liver test abnormalities normalized in 81% of patients after the addition of allopurinol. Sixteen (21%) patients had to discontinue combination therapy. The percentage of patients still using combination therapy at 6, 12, 24, and 60 months was 87%, 85%, 76%, and 65%, respectively.

Conclusions: Long-term combination therapy with allopurinol and low-dose thiopurines is an effective and well-tolerated treatment in IBD patients with a skewed thiopurine metabolism.

Publication types

  • Clinical Trial
  • Multicenter Study

MeSH terms

  • Adolescent
  • Adult
  • Allopurinol / metabolism
  • Allopurinol / therapeutic use*
  • Azathioprine / metabolism
  • Azathioprine / therapeutic use*
  • Colitis, Ulcerative / drug therapy*
  • Colitis, Ulcerative / metabolism
  • Crohn Disease / drug therapy*
  • Crohn Disease / metabolism
  • Drug Administration Schedule
  • Drug Therapy, Combination
  • Female
  • Humans
  • Immunosuppressive Agents / metabolism
  • Immunosuppressive Agents / therapeutic use*
  • Maintenance Chemotherapy
  • Male
  • Medication Adherence
  • Mercaptopurine / metabolism
  • Mercaptopurine / therapeutic use*
  • Middle Aged
  • Treatment Outcome
  • Young Adult


  • Immunosuppressive Agents
  • Allopurinol
  • Mercaptopurine
  • Azathioprine