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': 'Which of the following prokinetic drugs has been implicated in causing serious ventricular arrhythmias, paicularly in patietns concurrently receiving erythromycin or ketoconazole? \nSelect and explain. \nA. Domperidone, B. Cisapride, C. Mosapride, D. Metoclopramide', 'role': 'user'}, {'content': 'Answer: B \nExplanation: (Ref: KDT 6/e p645) Cisapride is a 5HT4 agonist that can block cardiac K+ channels at high concentration. When these are administered with microsomal enzyme inhibitors (like erythromycin or ketoconazole), polymorphic ventricular tachycardia can result. Mosapride and tegaserod are other 5HT4 agonists that are devoid of arrhthmogenic action.', 'role': 'assistant'}]