Improvement in pain and bowel function in female irritable bowel patients with alosetron, a 5-HT3 receptor antagonist

Background: No currently available treatment provides consistent relief of irritable bowel syndrome, Colonic sensory and motor function are modulated partly through 5HT(3)-receptors. Aim: To evaluate effects of the 5HT(3)-receptor antagonist, alosetron, in i rritable bowel syndrome. Methods: Randomized, double-blind, placebo-controlled, dose-ranging (1, 2, 4, 8 mg b.d. alosetron), 12-week trial in 370 patients with diarrhoea-predo minant or alternating constipation and diarrhoea irritable bon el syndrome, Weekly measurement of adequate relief was the key endpoint: other irritabl e bowel syndrome symptoms were collected daily using an electronic phone sy stem. Results: Alosetron (1 mg or 2 mg b.d.) significantly (P < 0.05 vs, placebo) increased the proportion of females, but not males, reporting adequate rel ief. Stool consistency, frequency and percentage days with urgency improved over placebo (P < 0.05) within the first month with all doses of alosetron , and persisted throughout the trial with all doses in female patients. Wit h 1 mg b.d. alosetron, females had improved stool consistency and urgency w ithin the first week, and adequate relief and improved stool frequency with in the first 2 weeks, There was no consistent improvement in bowel function among male patients. Conclusion: In female irritable bowel syndrome patients with predominant di arrhoea or alternating constipation and diarrhoea, alosetron is effective i n treatment of abdominal pain and discomfort and bowel-related symptoms.