ANIMAL TOXICOLOGY

Preclinical subacute and chronic toxicity studies in rats have shown the kidney to be the major target organ of olsalazine toxicity. At an oral daily dose of 400 mg/kg or higher, olsalazine treatment produced nephritis and tubular necrosis in a 4-week study; interstitial nephritis and tubular calcinosis in a 6-month study, and renal fibrosis, mineralization and transitional cell hyperplasia in a 1-year study.

CLINICAL STUDIES

Two controlled studies have demonstrated the efficacy of olsalazine as maintenance therapy in patients with ulcerative colitis. In the first, ulcerative colitis patients in remission were randomized to olsalazine 500 mg B.I.D. or placebo, and relapse rates for a six month period of time were compared. For the 52 patients randomized to olsalazine, 12 relapses occurred, while for the 49 placebo patients, 22 relapses occurred. This difference in relapse rates was significant (p<.02).

In the second study, 164 ulcerative colitis patients in remission were randomized to olsalazine 500 mg B.I.D. or sulfasalazine 1 gram B.I.D., and relapse rates were compared after six months. The relapse rate for olsalazine was 19.5% while that for sulfasalazine was 12.2%, a non-significant difference.

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