otrexate and infl iximab. Furthermore, indications are preferred in which surgery is thought to be inappropriate. The standard 6-TG dosage should not exceed 25 mg daily. Routine laboratory controls are mandatory in short intervals. Liver biopsies should be performed after 6-12 months, three years and then three-yearly accompanied by gastroduodenoscopy, to monitor for potential hepatotoxicity, including nodular regenerative hyperplasia (NRH) and veno-occlusive disease (VOD). Treatment with 6-TG

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... ust be discontinued in case of overt or histologically proven hepatotoxicity. Infl ammatory bowel disease (IBD) is an umbrella term for Crohn's disease (CD), ulcerative colitis (UC) and indeterminate colitis (IC). These entities are characterized by a chronic intestinal infl ammation of relapsing clinical Key Words 6-Thioguanine ؒ Thiopurine ؒ Infl ammatory bowel disease ؒ Crohn's disease and ulcerative colitis Abstract Recently, the suggestion to use 6-thioguanine (6-TG) as an alternative thiopurine in patients with infl ammatory bowel disease (IBD) has been discarded due to reports about possible (hepato) toxicity. During meetings arranged in Vienna and Prague in 2004, European experts applying 6-TG further on in IBD patients presented data on safety and effi cacy of 6-TG. After thorough evaluation of its risk-benefi t ratio, the group consented that 6-TG may still be considered as a rescue drug in stringently defi ned indications in IBD, albeit restricted to a clinical research setting. As a potential indication for administering 6-TG, we delineated the requirement for maintenance therapy as well as intolerance and/or resistance to aminosalicylates, azathioprine, 6-mercaptopurine, meth-