This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Pharmacology
[{'content': 'A patient on cisplatin therapy develops intractable vomiting on the third day of treatment. Agent of choice for controlling this vomiting is: \nSelect and explain. \nA. Aprepitant, B. Ondansetron, C. Metoclopramide, D. Prochlorperazine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (Ref: Katzung 10/e p1027, 1028) Cisplating induced vomiting has two phases. Early Phase: It occurs within first 24 hours. 5HT3 antagonists like ondansetron are the agents of choice for this condition. Delayed Phase: Vomiting occurring ater 24 hours is less responsive to ondansetron and other drugs. It is best controlled by substance Pantagonist like aprepitant.', 'role': 'assistant'}]