Alosetron ((Z)-2-butenedioate) is primarily used in the treatment of severe diarrhea-predominant irritable bowel syndrome (IBS-D) in women who have not responded adequately to conventional therapies. It works by selectively blocking serotonin 5-HT3 receptors in the gastrointestinal tract, which helps to slow down bowel movements, reduce abdominal pain, and alleviate discomfort associated with IBS-D. This medication is typically prescribed when other treatments have failed, as it carries a risk of serious side effects, such as ischemic colitis. Patients are usually closely monitored during treatment to ensure safety and efficacy. Its targeted action makes it a valuable option for managing severe symptoms in specific patient populations.