<prompt> Which of the following drugs can cause Torsadesde pointes?QuinidineLignocaineEsmololFlecainide  <response>: Ans. A QuinidineRef: Katzung 10the p224; KDT 8the p574Torsadesde 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. 