On tolerability and safety of a maintenance treatment with 6-thioguanine in azathioprine or 6-mercaptopurine intolerant IBD patients.

AIM: To determine the tolerability and safety profile of a low-dose maintenance therapy with 6-TG in azathioprine (AZA) or 6-mercaptopurine (6-MP) intolerant inflammatory bowel disease (IBD) patients over a treatment period of at least 1 year. METHODS: Database analysis. RESULTS: Twenty out of ninety-five (21%) patients discontinued 6-TG (mean dose 24.6 mg; mean 6-TGN level 540 pmol/8 x 10(8) RBC) within 1 year. Reasons for discontinuation were GI complaints (31%), malaise (15%) and hepatotoxicity (15%). Hematological events occurred in three patients, one discontinued treatment. In the 6-TG-tolerant group, 9% (7/75) could be classified as hepatotoxicity. An abdominal ultrasound was performed in 54% of patients, one patient had splenomegaly. CONCLUSION: The majority of AZA or 6-MP-intolerant IBD patients (79%) is able to tolerate maintenance treatment with 6-TG (dosages between 0.3 and 0.4 mg/kg per d). 6-TG may still be considered as an escape maintenance immunosuppressant in this difficult to treat group of patients, taking into account potential toxicity and efficacy of other alternatives. The recently reported hepatotoxicity is worrisome and 6-TG should therefore be administered only in prospective trials.

Prolonged thioguanine therapy is well tolerated and safe in the treatment of ulcerative colitis.

BACKGROUND: Thioguanine has been used for the treatment of inflammatory bowel disease, in particular for patients who failed conventional thiopurine therapy. To date, thioguanine has been infrequently studied in ulcerative colitis. AIM: To evaluate the tolerability, safety and efficacy of thioguanine in the treatment of ulcerative colitis. METHODS: A database analysis was performed on inflammatory bowel disease patients who had failed conventional thiopurine therapy and were treated with thioguanine. Rates and reasons for treatment failure were assessed. Laboratory values, abdominal ultrasonography, liver biopsy and endoscopic remission rates were evaluated. RESULTS: Forty-six patients were included and median treatment duration was 22 months (range 0.3-72.0). Nine patients failed thioguanine therapy: six due to adverse events, three due to therapy resistance. Concomitant treatment with aminosalicylates protected against thioguanine failure (hazard ratio (HR) 0.11, 95% CI 0.03-0.48). When performed, ultrasonography (n = 21) revealed no suspected therapy-related pathology in all but one patient, in whom hepatomegaly was observed. Liver histology (n = 12) predominantly revealed no abnormalities (n = 4) or non-specific regeneration (n = 4); none showed nodular regenerative hyperplasia. At follow-up, 40% of colonoscopies revealed endoscopic remission as compared with 10% at baseline (P = 0.180). CONCLUSIONS: Long-term use of thioguanine appears to be well tolerated and relatively safe in ulcerative colitis patients who failed conventional thiopurine therapy.