This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'All of the following is used as antiemetic, EXCEPT: \nSelect and explain. \nA. Granisetron, B. Dolasetron, C. Palonosetron, D. Alosetron', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Alosetron is a 5-HT3 antagonist that has been approved for the treatment of patients with severe IBS with diarrhea. Four other 5-HT3 antagonists (ondansetron, granisetron, dolasetron, and palonosetron) have been approved for the prevention and treatment of nausea and vomiting (see Antiemetics); however, their efficacy in the treatment of IBS has not been determined. The differences between these 5-HT3 antagonists that determine their pharmacodynamic effects have not been well studied Ref: Katzung 11th edition Chapter 60.', 'role': 'assistant'}]