Frequent minor side effects are associated with
sulfasalazine. The realization that it is the
5-aminosalicylic acid moiety that is the active component of
sulfasalazine and that the side effects are probably due to the
sulfapyridine has prompted the search for a similar but safer compound.
Olsalazine, consisting of two molecules of 5-ASA without
sulfasalazine may avoid the problems due to
sulfasalazine. One hundred one patients were entered into a double-blind placebo-controlled study of the use of
olsalazine (2 g daily) in preventing relapse in patients who had recently recovered from an acute attack of
ulcerative colitis. Patients were treated for 12 months. Forty-nine were randomized to
olsalazine (39 with limited and 10 with extensive disease) and 52 to placebo (42 with limited and 10 with extensive disease). Life-table analysis showed that the median time to relapse in patients on
olsalazine was 342 days, which was significantly longer than the 100 days in the placebo group (P = 0.024). The most important side effect experienced with
olsalazine that necessitated withdrawal from the study was "
drug-induced
diarrhea" in 16% (8/49). There was a similar incidence of minor side effects reported in the two groups, and in no patients were major or dangerous side effects reported. In patients who did not develop
diarrhea,
olsalazine was well tolerated and successfully prevented rapid relapse in the recently ill patients entered into this study.