Low allopurinol doses are sufficient to optimize azathioprine therapy in inflammatory bowel disease patients with inadequate thiopurine metabolite concentrations. - Curkovic, Ivanka; Rentsch, Katharina; Frei, Pascal; Fried, Michael; Rogler, Gerhard; Kullak-Ublick, Gerd; Jetter, Alexander (European Journal of Clinical Pharmacology, 2013)