Friedman AB, et al. - This research was formulated in order to evaluate the efficacy of allopurinol-thiopurine combination and to comparatively analyze 2 doses of allopurinol in patients with clinically active or steroid-dependent IBD and thiopurine shunting. It was observed that low-dose allopurinol-thiopurine combination safely reversed shunting and optimized 6-thioguanine nucleotides (6TGN) with related improvement in disease activity. Preference was given for 100 mg/d allopurinol as a result of its greater metabolite profile stability and lower thiopurine dose without additional toxicity.