Introduction Conventional thiopurines (Azathioprine/6-Mercaptopurine) are considered to be safe and effective in the treatment of inflammatory bowel disease (IBD). Unfortunately more than 50% of patients discontinue thiopurine therapy, mainly due to the development of adverse events or therapy resistance¹. In recent years, 6-thioguanine (TG) has been used as an alternative thiopurine in IBD patients failing to tolerate or to respond to conventional thiopurine therapy. The aim of this study was to evaluate the tolerability, safety and efficacy of 6-thioguanine in the treatment of IBD patients in a District General Hospital (DGH).

Methods A retrospective database analysis was performed on all IBD patients who had previously failed to respond or to tolerate conventional thiopurine therapy and were subsequently treated with TG at 20 mg once daily. Rates and reasons for treatment failure were assessed. Clinical features, laboratory values, abdominal imaging and endoscopic remission rates were evaluated.

Results Total of twelve patients received TG and median treatment duration was 8 months (range 1–12). There were 7(58%) female and 5(42%) male. Mean age was 37 years (range 19–62). 6/12(50%) patients had Ulcerative Colitis (UC) and 6/12(50%) had Crohn’s Disease (CD). Indications for initiation of 6-thioguanine therapy were conventional thiopurine intolerance 10(83%) and non-response to treatment 2(17%).

Two patients stopped taking treatment within first month due to fear of side effects; one of them wanted to become pregnant. Of 10 patients two failed TG therapy: one due to adverse event (hair loss) and other due to therapy failure. 4/10(40%) patients had partial response, having occasional mild flare ups while further 6/10(60%) patients remained in sustained clinical remission at 6 months on treatment, although one of the patient did not turn up to follow up appointment following 6 months of therapy. Tolerability and efficacy rates were similar in both UC and CD. All patients were closely monitored and no abnormality in liver function tests detected.

Conclusion Our study showed that TG was well tolerated in this selected group of difficult to treat patients. In addition, the use of small dose 20mg daily of TG appears to be relatively safe in IBD patients who failed conventional thiopurine therapy. Well designed prospective trials are required to further evaluate the safety and efficacy of 6-thioguanine.

Disclosure of Interest None Declared.

Reference

1. 1. Jharap B, Seinen ML, De Boer NK, et al. Inflamm Bowel Dis 2010, doi:10.1002/ibd.21221