Mesalamine-associated thrombocytopenia

We describe a case of a 25-yr-old woman with ulcerative colitis who develop ed marked thrombocytopenia during treatment and upon rechallenge with oral mesalamine. In contrast to its parent drug, sulfasalazine, which has often been reported to cause serious blood disorders, particularly agranulocytosi s, mesalamine has rately been implicated as a cause of serious blood disord ers. Although previous cases of hematological toxicity have been described in patients taking mesalamine, none of these patients were rechallenged in an effort to prove causality between 5-aminosalicyclic acid and the hematol ogical abnormality as well as outrule the possible "autoimmune" contributio n of inflammatory bowel disease to the hematological toxicity of these agen ts. This report demonstrates that mesalamine has the potential, Like sulpha salazine, to cause marked thrombocytopenia in an idiosyncratic fashion. All patients receiving mesalamine therapy, either orally or topically should h ave regular, complete blood profiles. (Am J Gastroenterol 1999;94:2304-2306 . (C) 1999 by Am. Coll. of Gastroenterology).