Description: Alosetron is a potent and selective 5-HT3 receptor antagonist. Alosetron blocks the actions of serotonin at 5-HT3 sites in the peripheral nervous system, particularly on enteric and nociceptive sensory neurons, thereby affecting the regulation of visceral pain, decreasing gastrointestinal contraction and motility, and decreasing gastrointestinal secretions. This agent is used to treat diarrhea-predominant irritable bowel syndrome in women only.