Ramosetron is a potent and selective antagonist of the serotonin (5-HT) receptor subtype 5-HT3 (Ki = 0.06 nM). It has little or no effect at other 5-HT receptor subtypes or at adrenergic or histamine receptors. Ramosetron competitively blocks serotonin-mediated contraction of the colon. It has applications in ameliorating diarrhea-predominant inflammatory bowel syndrome and postoperative nausea and vomiting.
