Hyposensitization trial using salazosulfapyridine in a case of mesalamine intolerance

A 47-year-old Japanese man was diagnosed with pancolitis-type ulcerative colitis. He was treated with mesalamine in a pH-dependent release form. On day 16 of administration, he was admitted because of fever and abdominal pain. We diagnosed his symptoms to be the side effects of mesalamine. Hyposensitization using unmodified and a time-dependent release form mesalamine was performed. On day 7 of mesalamine hyposensitization, a colonoscopy was performed. The patient presented with the same allergic symptoms 9 h after the administration of an oral sodium phosphate solution. Eventually, he was orally administered a course of salazosulfapyridine (SASP) at an initial dose of 2.5 mg/day, which was increased to 2000 mg/day. It is generally recognized that SASP intolerance is an indication to switch from SASP to mesalamine. The need to switch treatment from mesalamine to SASP is, therefore, rare because allergic reactions to mesalamine do not occur frequently. We report a very rare case which was presented with abdominal pain and myalgia because of intolerance to mesalamine in whom hyposensitization with and introduction of SASP were successful.