6-Mercaptopurine for Azathioprine Intolerant Inflammatory Bowel Disease: Literature Search and Reappraisal of Own Data.

Thiopurines have been shown to effectively maintain remission of both Crohn's disease (CD) and ulcerative colitis (UC), and to behave as disease modifiers if used for >12 months in UC. Gastric intolerance manifesting as nausea constitutes a demanding drawback of thiopurines, at times forcing treatment discontinuance. A few studies have now indicated that some patients might tolerate mercaptopurine (6-MP) for azathioprine. In this paper, we review the literature, and reappraise our own data against the published figures. The data which form the basis for this study span over all visit reports that were released between January 2008 and December 2011 in a primary care Hospital, in Turin, Italy. For the aim of this study we searched our own database and the MedLine using the key-words "azathioprine", "mercaptopurine", "thiopurine", "inflammatory bowel disease", "Crohn's disease", "ulcerative colitis". We retrieved 85 azathioprine prescriptions for 42 UC, 37 CD, and 6 miscellaneous patients. There were 10 episodes of gastric intolerance to azathioprine, which were switched to 6-MP: 6 out of 10 (60%) responded and tolerated the switch drug in a median follow-up of 66 months. Female gender prevailed (p=0.038) in the azathioprine intolerant subset. A trial with 6-MP is worth being offered to azathioprine intolerant inflammatory bowel disease subjects at any center matching the standard figures of specific performance.