The FDA has approved mesalamine (Canasa, Axcan Scandipharm Inc, Birmingham, Ala) rectal suppositories, 500 mg, for treatment of active ulcerative proctitis. This anti-inflammatory drug's mechanism of action appears to be topical rather than systemic.
Mesalamine was approved on the basis of two double-blind, placebo-controlled, multicenter studies conducted in North America in patients with mild-to-moderate active ulcerative proctitis.
The main difference between the studies was dosage regimen: 500 mg three times daily in study 1 and 500 mg twice daily in study 2. The efficacy was similar. Of the 173 patients in both trials, 89 received mesalamine suppositories and 84 received placebo suppositories. Compared with placebo, mesalamine suppository treatment was statistically superior (P<.01)to placebo in both trials in improving stool frequency, rectal bleeding, mucosal appearance, disease severity, and overall disease activity after 3 and 6 weeks of treatment. Daily diary records indicated significant improvement in rectal bleeding in the first week of therapy, while tenesmus and diarrhea improved significantly within 2 weeks. Investigators rated patients receiving mesalamine much improved compared with patients receiving placebo (P<.001).