6-thioguanine treatment in inflammatory bowel disease: A critical appraisal by a European 6-TG working party

Recently, the suggestion to use 6-thioguanine (6-TG) as an
alternative thiopurine in patients with inflammatory 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 efficacy of 6-TG. After thorough evaluation of
its risk-benefit ratio, the group consented that 6-TG may still be
considered as a rescue drug in stringently defined 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,
methotrexate and infliximab. 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 must be
discontinued in case of overt or histologically proven
hepatotoxicity. Copyright (c) 2006 S. Karger AG, Basel.