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': 'Ketoconazole should not be given to a patient being treated with astemizole because: \nSelect and explain. \nA. Ketoconazole induces the metabolism of astemizole, B. Dangerous ventricular arrhythmias can occur, C. Astemizole inhibits the metabolism of ketoconazole, D. Astemizole antagonizes the antifungal action of ketoconazole', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ketoconazole, erythromycin and clarithromycin are potent inhibitors of microsomal enzymes. Astemizole, terfenadine and cisapride are the drugs that can block cardiac K+ channels at high concentration. If administered along with microsomal enzyme inhibitors, these drugs can result in torsades de pointes, a serious polymorphic ventricular tachycardia.', 'role': 'assistant'}]