This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pharmacology
[{'content': "Which of the following drugs can cause Torsades'de pointes? \nSelect and explain. \nA. Quinidine, B. Lignocaine, C. Esmolol, D. Flecainide", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. (A) Quinidine(Ref: Katzung 10th/e p224; KDT 8th/e p574)*Torsades'de pointes is a polymorphic ventricular tachycardia that is usually caused due to blockade of delayed rectifier K+ channels in the heart.*It manifests in the ECG as QTc prolongation.*Drugs having cardiac K+ channel blocking activities can cause this arrhythmia. These include:-Class Ia antiarrhythmics -Quinidine, Procainamide (Na+ and K+ channel blockers)-Class III antiarrhythmics -Bretylium, sotalol, dofetilide, ibutilide and amiodarone (K+ channel blockers)-Other drugs like Terfenadine, Cisapride, Astemizole, Sparfloxacin, Gatifloxacin, Grepafloxacin, Mefloquine, Pentamidine, Thioridazine, Ziprasidone etc.", 'role': 'assistant'}]