A double-blind, randomized, placebo-controlled dose-ranging study to evaluate the efficacy of alosetron in the treatment of irritable bowel syndrome

Background: Irritable bowel syndrome is a common gastrointestinal disorder characterized by abdominal pain and discomfort and altered bowel habit. Ant agonism at the 5-HT3 receptor may be of benefit in the treatment of irritab le bowel syndrome. Aims: To evaluate the effect of 12 weeks of treatment with alosetron, a 5-H T3 receptor antagonist at doses of 0.1 mg b.d., 0.5 mg b.d. and 2 mg b.d. i n irritable bowel syndrome patients. Methods: A double-blind, placebo-controlled, parallel-group study with a 2- week screening and a 12-week treatment period was conducted. A total of 462 patients (335 female) recorded details of the severity of their abdominal pain, and bowel function daily on a diary card throughout the study. At mon thly clinic visits patients recorded the severity of their abdominal pain/d iscomfort and diarrhoea on a visual analogue scale. Results: In the total population and in the female subpopulation (but not i n males) alosetron 2 mg b.d. significantly increased the proportion of pain -free days and decreased the visual analogue scale score for diarrhoea comp ared with placebo. Alosetron at doses of 0.5 mg b.d. and 2 mg b.d. led to a significant hardening of stool, and a reduction in stool frequency in the total population. Conclusion: Alosetron at a dose of 2 mg b.d. is an effective treatment for female patients with irritable bowel syndrome.