Is mycophenolate mofetil an effective alternative in azathioprine-intolerant patients with chronic active Crohn's disease?

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Abstract
Up to 50% of patients with Crohn's disease (CD) develop steroid-dependent or refractory disease requiring immunosuppression. Azathioprine (AZA) is usually used for this purpose but must be withdrawn in up to 10% of patients because of adverse events. Mycophenolate mofetil (MMF) is of proven efficacy and safety in transplantation and in some autoimmune disorders. The aim of the present study was to investigate the effect of MMF, especially in AZA-intolerant patients with chronic active CD, in comparison to a matched control group treated with AZA. In a retrospective study, 15 patients treated with MMF and 30 randomly chosen, matched patients treated with AZA for chronic active CD were compared over a period of 1 yr. Intolerance to AZA was the indication for MMF. Crohn's Disease Activity Index (CDAI), steroid demand, extraintestinal manifestations, and hematological and biochemical parameters were assessed at the start of therapy and 1, 2, 3, 6, 9, and 12 months thereafter. All patients who completed the 12 months of treatment (77% AZA, 60% MMF) achieved remission. Under MMF, the cumulative prednisolone dose could be reduced by 1 g in the first half year, whereas, under AZA, this reduction was possible only in the second half year. MMF patients had almost twice as many flare-ups (80% vs 47%). Adverse events prompted the withdrawal of AZA in five patients (17%) and of MMF in three (20%). Both drugs are effective in inducing remission. AZA seems to be more effective in maintaining remission. The onset of therapeutic effect is delayed less under MMF. Both drugs have steroid sparing potential, which is delayed under AZA. It seems that AZA still is the immunouppressant of choice in chronic active CD, but MMF is a reasonable alternative in patients who do not tolerate AZA.