Mycophenolate induced diarrhoea.

Mycophenolate (MMF) has arisen as an important addition in the immunosuppression armamentarium. GI disturbances (diarrhea) and bone marrow suppression are its main side effects requiring dose reduction or even withdrawal. The mechanism of diarrhoea is unknown, although some theories have been postulated. We evaluated three of our patients on MMF who came to us with chronic diarhoea. Their evaluation consisted of CBC, stool routine examination, stool culture, endoscopy and biopsy. Histopathologic examination in all three cases showed villous atrophy. All of them improved with discontinuation of MMF and addition of folic acid suggesting that diarrhoea was related to MMF. Since this complication is seen in only a few cases, we can hypothesize that it may be due to lower levels of the enzyme inosine monophosphate dehydrogenase (IMPDH)--the site of action of MMF.