Background: We and others have previously reported the utility of low dose azathioprine and allopurinol co-therapy in patients who develop side effects to standard dose azathioprine. This practice allows patients the convenience of continuing an oral drug and leads to health care savings by avoiding biologic drugs. In our practice we have identified that a small number of patients are intolerant to allopurinol. In these patients we substitute allopurinol for the alternative xanthine oxidase inhibitor febuxostat. We report our experience at one year.
Methods: We maintain a prospective database of all IBD patients treated with immunosuppressive therapy. We searched our database for all patients who were intolerant of allopurinol and were treated with febuxostat. Data on disease type, age, duration of treatment, tolerability, week 4–6 azathioprine metabolite levels and steroid free remission were reviewed.
Results: 6 patients were identified 1 (16.7%) was female. Mean age; 48 years, (range 38–65). Disease type was Crohn's disease; 3 (50%), ulcerative colitis; 3 (50%).
In 5 patients side effects developed after starting allopurinol for treatment of IBD; side effects reported were; fatigue, nausea, diarrhoea, pruritus, arthralgia and paraesthesia. 1 patient started febuxostat in primary care for treatment of gout prior to commencing thiopurine therapy. All 6 (100%) tolerated febuxostat. 6-thioguanine levels (taken at week 4–6) were available in 5 (83%), mean TGN; 532 (range 196–1130). Mean 6-MMPN; 182 (range <100–224).
5 (83%) patients were in a steroid free remission at 1 year and continue on low dose thiopurine and febuxostat. 1 patient stopped 1 month after commencing low dose mercaptopurine and febuxtostat due to developing lichen sclerosis.
Conclusions: In this small case series febuxostat when combined with low dose azathioprine was efficacious and well tolerated in patients who were previously intolerant of allopurinol.
We recommend a trial of febuxostat in patients intolerant of allopurinol. This strategy could reduce the need for biologic drugs and lead to cost savings in clinical practice.