MMF GI Toxicity Diarrhoea Post-Transplant — ESENeph MCQ

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ModerateTransplantationMMF GI Toxicity Diarrhoea Post-TransplantESENeph

A 55-year-old man is 2 years post-kidney transplant on tacrolimus, MMF, and prednisolone. He develops persistent diarrhoea for 6 weeks. CMV PCR is negative. C. difficile toxin is negative. Colonoscopy shows non-specific colitis. What is the most likely drug cause?

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Correct answer: E — Mycophenolate mofetil

MMF-associated GI toxicity (diarrhoea, nausea, abdominal pain, rarely colitis) is the most common drug-related adverse effect in transplant recipients, affecting up to 30% of patients. The mechanism involves direct inhibition of inosine monophosphate dehydrogenase (IMPDH) in rapidly dividing GI epithelial cells, impairing mucosal regeneration. Management options include: (1) dose reduction of MMF (first-line), (2) switching to enteric-coated mycophenolate sodium (Myfortic), which may reduce upper GI symptoms, (3) splitting doses (e.g., QDS instead of BD), or (4) switching to azathioprine (lower immunosuppressive potency). MMF should not be stopped without discussing rejection risk. CMV and C. difficile must be excluded first.

Reference: Bunnapradist & Neri 2010 – MMF GI Toxicity; KDIGO 2009 – Transplant Guideline