Objectives: Bowel urgency is one of the most bothersome symptoms for nonconstipated IBS patients. The efficacy of alosetron in control of bowel urgency and Global Improvement of IBS symptoms were evaluated in a multicenter double-blind, randomized, placebo-controlled study.
Methods: Female IBS patients with lack of satisfactory control of bowel urgency were randomized 2:1 to alosetron 1 mg twice daily or placebo treatment groups. The primary endpoint was the proportion of days with satisfactory control of bowel urgency during the 12-wk treatment period and 2-wk follow-up period. Secondary endpoints included IBS Global Improvement (responder defined as patient-reported moderate or substantial improvement in IBS symptoms) and improvements in bowel function (stool frequency, consistency, and sensation of incomplete evacuation).
Results: A total of 801 women were randomized to the alosetron (n = 532) or placebo groups (n = 269). Physicians classified 98% of patients with diarrhea-predominant IBS. Patients treated with alosetron had a significantly greater proportion of days with satisfactory control of urgency compared to placebo for the treatment period (73% vs 57%, p < 0.001). A significantly greater number of patients treated with alosetron were IBS Global Improvement responders compared to placebo at week 12 (76% vs 44%, p < 0.001). IBS Global Improvement responders had more days with satisfactory control of urgency at week 12 (88% vs 48%) as well as firmer stools, fewer stools/day, and fewer days with incomplete evacuation compared with nonresponders. Alosetron-treated patients showed improvements in bowel functions compared to placebo-treated patients. Constipation was the most commonly reported adverse event.