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

Abstract

Background : No currently available treatment provides consistent relief of irritable bowel syndrome. Colonic sensory and motor function are modulated partly through 5HT₃‐receptors. Aim : To evaluate effects of the 5HT₃‐receptor antagonist, alosetron, in irritable 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‐predominant or alternating constipation and diarrhoea irritable bowel syndrome. Weekly measurement of adequate relief was the key end‐point; other irritable bowel syndrome symptoms were collected daily using an electronic phone system. 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 relief. 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. With 1 mg b.d. alosetron, females had improved stool consistency and urgency within the first week, and adequate relief and improved stool frequency within the first 2 weeks. There was no consistent improvement in bowel function among male patients. Conclusion : In female irritable bowel syndrome patients with predominant diarrhoea or alternating constipation and diarrhoea, alosetron is effective in treatment of abdominal pain and discomfort and bowel‐related symptoms.