Dose-ranging study of mesalamine (PENTASA) enemas in the treatment of acute ulcerative proctosigmoiditis: results of a multicentered placebo-controlled trial. The U.S. PENTASA Enema Study Group.

The safety and efficacy of mesalamine enemas were determined ina dose‐ranging study enrolling 287 patients with ulcerative proctitis and proctosigmoiditis in a double‐blind, placebo‐controlled, multicenter trial. Patients were randomized to receive placebo, 1, 2, or 4 g in 100 ml mesalamine (PENTASA) enemas h.s. for 8 weeks. Efficacy was assessed by clinical, sigmoidoscopic, and histologic improvement, as well as by induction of remission. Sixty‐seven percent, 65%, and 75% of patients receiving 1‐, 2‐, and 4‐g enemas were markedly improved according to the physician's global assessment compared with 27% of patients treated with placebo. The mean improvement in sigmoidoscopic index was 5.8, 5.9, and 6.4 points (on a 15‐point scale) for the 1‐, 2‐, and 4‐g enema groups compared with a decrease of 1.8 points for the placebo group. Improvement in biopsy scores was observed in 47, 55, and 59% of 1‐, 2‐, and 4‐g groups contrasted with 27% of the placebo‐treated patients. All three doses were significantly more effective than placebo in reducing symptoms and trips to the toilet compared with placebo. No dose‐response relation was demonstrated. The safety profile was similar to that of placebo. In conclusion, mesalamine enemas are effective as a single agent in the short‐term treatment of distal ulcerative colitis without an apparent dose response between 1 and 4 g nightly.