This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Histamine, 5-HT and PGs, Subject name: Pharmacology
[{'content': 'DOC for chemotherapy induced vomiting is? \nSelect and explain. \nA. Graneseteron, B. Prazosin, C. Clonidine, D. Diphenyhydramine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Granisetron: Serotonin 5-HT3 receptor antagonist. Used as an antiemetic treating nausea & vomiting following chemotherapy & radiotherapy. Main effect: These drugs antagonize the 5HT3 receptor present in CTZ area which is stimulated on release of 5HT during cancer therapy. Prazosin is alpha blocker used in BPH. Clonidine is alpha agonist used in hypeension. Diphenyhydramine is first generation antihistaminic', 'role': 'assistant'}]