Effect of Combination Therapy of Allopurinol and Reduced Dose of Azathioprine on Inflammatory Bowel Disease (IBD)

Background: Thiopurine, Azathioprine and 6–Mercaptopurine are the maintenance therapies for inflammatory bowel disease (IBD); however, treatment frequently fails due to adverse drug reactions. This study is aimed at conducting combination therapy of allopurinol and reduced dose of Azathioprine in order to study the complications and treatment effect in IBD patients. Method: Some IBD patients with indication for treatment using Azathioprine were divided into two groups, each including 32 patients: (1) Group A in which patients received the combination therapy of allopurinol (100 mg/d) and reduced dose of Imuran down to 50% daily; and (2) Group B in which patients received standard therapy. The patients were evaluated for 24 weeks in terms of complications and response to treatment. Results: Among patients who received polytherapy, i.e. Group A, 12.5% of them suffered some complications such as neutropenia as the most common one (6.2%), and then nausea and loss of appetite. From those treated with standard therapy, i.e. Group B, 34.4% suffered some complications such as gastrointestinal intolerance as the most common one (18.9%), neutropenia (6.2%) and increased liver enzymes (6.2%). There was a significant relationship between the complications and type of the treatment (p = 0.039), however, remission rate in Group A was 87.5% and the same rate in Group B was 81.2% which showed no significant difference. Conclusions: In patients with stable IBD, the combination therapy of allopurinol and Azathioprine is effective in reducing drug complications of Azathioprine, especially for hepatic and gastrointestinal complications. Nevertheless, the remission level in polytherapy was not greater than that of standard therapy. In patients with combination therapy,